Swift培訓

2019-11-14 20:15:51

字體：大中小

來源：轉載

供稿：網友

　　本篇是Swift內部培訓整理的PPT材料，主要內容來源于蘋果Swift編程語言官方教程，參考了網上的一些視頻課程內容。在教程介紹完之后，本人附帶實現了一個項目開發中的常用場景的Demo：基于導航欄和Tab欄的應用。

1.Swift概述

　　我們先來看一篇文章：《蘋果新貴 Swift之前世今生》

　　Swift是用于設計iOS及Mac OS X應用的一門新語言。

1.1.Swift特點

Swift保留了C與Objective-C的優點，并摒棄其為了兼容C語言所受的限制；
Swift吸納了安全編程模式，并新增了一些現代化功能，使其更易使用、更為靈活、更具樂趣。
Swift的簡潔風格與廣受歡迎的成熟框架Cocoa/Cocoa Touch相結合，將為重新構思軟件的開發過程帶來新機遇；
Swift內存管理采用ARC風格。

1.2.Swift代碼的文件擴展名

　　*.swift

2.第一個Swift程序

2.1.使用Xcode PRoject編寫

2.2.使用Playground編寫

　　我們可以基于 Playground 做這些事情：

學習：通過 Playground 學習 Swift，制作 Swift 教程實現交互式學習，同時還可以培訓其他初學者。
代碼開發：執行算法程序，迅速看到算法結果，跟蹤變量；執行繪圖程序，即時看到圖像結果，及時調整。執行通用代碼，查看變量的改變情況。
實驗性代碼：無需創建項目，直接打開一個獨立的Playground文件即可編寫代碼，嘗試調用新的 API。

3.常量與變量

　　let關鍵詞聲明常量，var關鍵詞聲明變量。

let maximumNumberOfLoginAttempts = 10  // 常量只有在初始化的時候可以賦值var currentLoginAttempt = 0

4.運算符和表達式

4.1.運算符

算術運算符：*、/、+、—、%、++、——
關系運算符：>、<、>=、<=、==、!=
布爾邏輯運算符：！、&&、||
三元運算符：？：

4.2.表達式

　　1.不指定數據類型

var a1 = 10var a2 = 20var a = a1 > a2 ? "a1":"a2"

　　2.指定數據類型

var a1:Int = 10var a2:Int = 20var a = a1 > a2 ? "a1":"a2"

　　3.可以有分號結尾

var a1:Int = 10; var a2:Int = 20var a = a1 > a2 ? "a1":"a2"

4.3.注釋

///*    */

5.數據類型

5.1.整型

　　Swift提供8、16、32、64位形式的有符號及無符號整數，這些整數類型遵循C語言的命名規約。與Swift中的所有類型一樣，這些整數類型的名稱以大寫字母開頭。

　　Swift還提供了一個整數類型Int；

在32位平臺，Int與Int32寬度一致；
在64位平臺，Int與Int64寬度一致；

　　Swift還提供了無符號整數類型UInt。

5.2.浮點型

單精度浮點(32位) Float
雙精度浮點(64位) Double

5.3.數字型

　　表示數字如下：

let decimalInteger = 17  // 表示是10進制let binaryInteger = 0b10001  // 二進制17let octalInteger = 0o21  // 8進制17let hexadecimalInteger = 0x11  // 16進制17

5.4.布爾類型

　　true和false

let orangesAreOrange = truelet turnipsAreDelicious = false

6.數據類型轉換

6.1.整型轉換

　　不同類型的整數常量或變量所能存儲的值域不同，需要顯示地轉換

let twoThousand:UInt16 = 2000let one:UInt8 = 1//let twoThousandAndOne = twoThousand + one  // 錯誤let twoThousandAndOne = twoThousand + UInt16(one)  // 正確

6.2.整型與浮點數轉換

　　整數與浮點數類型之間的轉換，需要顯示地轉換：

let three = 3let pointOneFourOneFiveNine = 0.14159let pi = Double(three) + pointOneFourOneFiveNine

7.字符串類型

7.1.字符串初始化

　　1.初始化

let someString = "Some string literal value"let wiseWords = "/"Imagination is more important than knowledge/" - Einstein"let dollarSign = "/x24"  // $,Unicode scalar U+0024

　　2.空值

var emptyString = ""  // 空串初始化var anotherEmptyString = String()  // 通過初始化函數初始化

　　3.空值判斷

if emptyString.isEmpty{    println("Nothing to see here")}if emptyString == ""{    println("Nothing to see here")}

7.2.字符串修改

　　var 聲明的可以修改，let不能修改。

var variableString = "Horse"variableString += " and carriage"

7.3.字符串插入

　　斜杠+括號+變量

let multiplier = 3let message = "/(multiplier) times 2.5 is /(Double(multiplier) * 2.5)"

7.4.字符串長度

　　使用countElements函數。OC中使用length屬性。

let unusualMenagerie = "Koala , Snail, Penguin"println("unusualMenagerie has /(countElements(unusualMenagerie)) characters")

7.5.比較字符串相等

let quotation = "We're a lot alike,you and I."let sameQuotation = "We're a lot alike,you and I."if quotation == sameQuotation{    println("These two strings are considered equal")}

8.元組(tuple)類型

　　元組將多個值組合為單個值。元組內的值可以是任意類型，各元素不必是相同的類型，元組在作為函數返回值時尤其有用。

　　1.定義方法1

let http404Error = (404,"Not Found")println("The status code is /(http404Error.0)");println("The status message is /(http404Error.1)");

　　2.定義方法2

let http200Error = (statusCode:404,discription:"Not Found")println("The status code is /(http200Error.statusCode)");println("The status message is /(http200Error.discription)");

9.可選(Optional)類型

9.1.使用可選類型

　　我們在如下情況下使用可選類型：

它有值但不確定；
沒有任何值。

let possibleNumber = "123"let convertedNumber:Int?=possibleNumber.toInt()

　　“Int?”是可選類型

if convertedNumber{    println("/(possibleNumber) has an Integer value of /(convertedNumber!)")}else{    println("/(possibleNumber) could not be convented to an integer")}

　　convertedNumber是從可選類型中取值

9.2.使用nil

　　我們可以為可選類型的變量設置nil值，表示沒有任何值。

var serverResponseCode:Int?=404serverResponseCode = nil

　　如果不是可選類型，那么是不能設置為nil的

10.數組

10.1.數組初始化

　　基本語法：

[value1,value2,value3]var shoppingList:String[] = [“Eggs","Milk"]

　　對比一下OC中的方式：

NSArray *array = @[@"aa",@"bb"];

10.2.數組追加元素

　　使用append函數追加或通過+操作符：

var shoppingList:String[] = ["Eggs","Milk"]shoppingList.append("Flour")shoppingList += ["Cheese","Butter"]

10.3.數組插入元素

　　使用insert方法：

var shoppingList:String[] = ["Eggs","Milk"]shoppingList.insert("Butter", atIndex: 0)shoppingList += ["Cheese","Chocolate Spread"]

　　比較一下OC中：

[array insertObject:@"dd" atIndex:1];

10.4.數組刪除元素

　　使用removeAtIndex方法

var shoppingList:String[] = ["Eggs","Milk","Butter"]let deleteItem = shoppingList.removeAtIndex(2)println(deleteItem)println(shoppingList)

10.5.數組長度

　　使用count屬性(和OC中一樣)：

var shoppingList:String[] = ["Eggs","Milk","Butter"]println("The shopping list contains /(shoppingList.count) items.")

10.6.數組遍歷

　　1.遍歷方法1

var shoppingList:String[] = ["Eggs","Milk","Butter"]for item in shoppingList{    println(item)}

　　2.遍歷方法2

　　有循環變量：

for(index,value) in enumerate(shoppingList){    println("Item /(index + 1):/(value)")}

11.字典

11.1.字典初始化

　　基本語法：

[key1:value1,key2:value2,key3:value3]var airports:Dictionary<String,String> = ["TYO":"Tokyo","DUB":"Dublin"]

11.2.字典追加元素

var airports:Dictionary<String,String> = ["TYO":"Tokyo","DUB":"Dublin"]airports["LHR"] = "Lonton"println("The dictionary of airports contains /(airports.count)")

11.3.字典刪除元素

　　通過removeValueForKey(key)方法刪除

var airports:Dictionary<String,String> = ["TYO":"Tokyo","DUB":"Dublin"]if let removedValue = airports.removeValueForKey("DUB"){    println("The removed airport's name is /(removedValue)")}else{    println("The airports dictionary does not contains a value for DUB")}

11.4.字典長度

　　使用count屬性

println("The count of airport's is /(airports.count)")

11.5.字典遍歷

　　1.遍歷字典

var airports:Dictionary<String,String> = ["TYO":"Tokyo","DUB":"Dublin"]for (airportCode,airportName) in airports{    println("/(airportCode):/(airportName)")}

　　2.遍歷鍵和值

for airportCode in airports.keys{    println("Airport code:/(airportCode)")}for airportName in airports.values{    println("Airport name/(airportName)")}

　　3.獲得鍵和值的數組

let airportCodes = Array(airports.keys)let airportNames = Array(airports.values)

12.控制語句

12.1.分支語句

　　1.條件語句if-else

if boolean-expression{statement1;}[else if boolean-expression{statement2;}][else{statement3;}]

　　2.多分支語句switch

switch some value to consider{case value1,value2,value3:respond to value1default:otherwise}

　　每個case不需要顯示地添加break,每個case至少有一條語句。可以比較任何類型。

12.2.循環語句

　　1.while語句

while condition{statements}

　　示例：

var i = 100var r = 0var s = 0var t = 0while i < 1000 {    r = i / 100 ;    s = (i - r * 100) / 10;    t = i - r * 100 - s * 10;    if(i == r * r * r + s * s * s + t * t * t){        println("i=/(i)");    }    i++}

　　2.do-while語句

do{statements}while condition

　　示例：

var i = 100var r = 0var s = 0var t = 0do{    r = i / 100 ;    s = (i - r * 100) / 10;    t = i - r * 100 - s * 10;    if(i == r * r * r + s * s * s + t * t * t){        println("i=/(i)");    }    i++}while i < 1000

　　3.for語句

for initialization;condition;increment{statements}

　　示例：

var i = 8var r = 0var s = 0for var j = 0;j <= i;j++ {    r = j * j;    s = j * j * j;    println("/(j)的平方：/(r) /(j)的立方：/(s)");}

　　4.for in語句

　　一般用于遍歷集合

　　1.遍歷范圍

for index in 1...5{    println("/(index) times 5 is /(index * 5)");}

　　2.忽略循環變量

let base = 3let power = 10var answer = 1for _ in 1...power{    answer *= base;}println("/(base) to the power of /(power) is /(answer)")

　　3.遍歷數組

let names = ["Anna","Alex","Jack"]for name in names{    println("Hello,/(name)")}

　　4.遍歷字典

let numberofLegs = ["spider":8,"ant":6,"car":4];for(animalName,legCount) in numberofLegs{    println("/(animalName) have /(legCount) legs")}

　　5.遍歷字符串

for character in "Hello"{    println(character)}

12.3.跳轉語句

continue：終止當次循環，接著進入下一次循環
break：終止循環；
fallthrough：其他語言沒有的，貫穿的意思，常用于switch語句中，示例如下：

let integerDescribe = 5var description = "The number /(integerDescribe) is"switch integerDescribe{case 2,3,5:    description += " a prise number,and also"    fallthroughdefault:    description += " an integer.";}

4.return

13.函數

13.1.函數定義

　　使用func定義一個函數。調用函數使用它的名字加上小括號中的參數列表。使用->分隔參數的名字和返回值類型。

　　函數聲明：

func greet(name:String,day:String) -> String{    return "Hello /(name),today is /(day)"}

　　函數調用：

greet("Bob", "Tuesday")

13.2.無返回值函數

func sayGoodBye(personName:String){    println("Goodbye,/(personName)");}sayGoodBye("Tony");

13.3.多返回值函數

　　使用元組類型返回多個值

func count(string:String) -> (vowels:Int,consonants:Int,others:Int){    var vowel = 0,consonant = 0,other = 0;    for character in string{        switch String(character).lowercaseString{        case "a","e","i","o","u":            ++vowel;        case "b","c","d","f","g","h","j","k","l","m","n","p","q","r","s","t","v","w","x","y","z":            ++consonant;        default:            ++other;        }    }    return (vowel,consonant,other);}let total = count("Some thing is change!");println("/(total.vowels)元音,/(total.consonants)輔音")

13.4.嵌入函數

func chooseStepFunction(backwards:Bool) -> (Int) -> Int{    func stepForward(input:Int) -> Int{        return input + 1    }    func stepBackward(input:Int) -> Int{        return input - 1    }    return backwards ? stepBackward : stepForward}var currentValue = -4// moveNearerToZero是一個函數指針let moveNearerToZero = chooseStepFunction(currentValue > 0)while currentValue != 0{    println("/(currentValue)......")    currentValue = moveNearerToZero(currentValue)}

14.閉包(Closure)

　　語法：

{(parameters) -> return type instatements}

　　示例：數組排序

　　采用函數實現：

let names = ["Chris","Alex","Ewa","Barry","Daniella"]func backwards(s1:String,s2:String) -> Bool{    return s1 > s2}// sort排序函數，backwards通過排序規則的函數var reversed = sort(names,backwards)println(reversed)

　　采用閉包實現：

var reversed = sort(names,{(s1:String,s2:String) -> Bool in return s1 > s2})println(reversed)

15.類與結構體

　　類和結構體有很多共性：

定義屬性存儲數據；
定義方法執行功能處理；
定義下標，通過下標訪問它們的值；
初始化它們的狀態；
通過擴展（Extension）擴展其功能；
遵守協議(Protocol)，協議提供一種特定的標準功能。

　　類比結構體多出的功能：

能夠繼承另外一個類；
能夠核對運行期對象的類型；
析構對象釋放資源；
引用計數允許一個類實例有多個引用。

15.1.類和結構體的定義

　　定義類和結構體：

class SomeClass{// class definition goes here}struct SomeStructure{// structure definition goes here}

　　示例：

struct Resolution{var width = 0var height = 0}class VideoMode{var resolution = Resolution()var interfaced = falsevar frameRate = 0.0var name:String?}

15.2.類和結構體的實例化

struct Resolution{var width = 0var height = 0}class VideoMode{var resolution = Resolution()var interfaced = falsevar frameRate = 0.0var name:String?}let someResolution = Resolution()// let someResolution = Resolution(width:10,height:20)let someVideoMode = VideoMode()

16.屬性

16.1.屬性的存儲

　　屬性的主要作用是存儲數據，可以分為常量屬性和變量屬性；

struct FixedLengthRange{    var firstValue:Int    let length:Int}var rangeOfThreeItems = FixedLengthRange(firstValue:0,length:3)rangeOfThreeItems.firstValue = 6// 注意：length是常量屬性，值是不可以修改的

16.2.延時存儲屬性

　　延時存儲屬性是初始化時候不分配值，直到第一次使用它。屬性@lazy聲明。

　　為什么要用延時存儲屬性？當一個屬性是一個龐大類時，并且這個屬性很少用到，那么就可以考慮使用延時存儲屬性，這樣可以避免大量數據加載到內存中。

class DataImporter{    var fileName = "data.txt"}class DataManager{    @lazy var importer = DataImporter()    var data = ""} let manager = DataManager();manager.data += "Some Data"manager.data += "Some more data"println(manager.importer.fileName)

　　去掉@lazy關鍵字在playground里面試試，看看有什么不一樣？

16.3.計算屬性

　　有的時候一些屬性是通過其他的屬性計算得出的，通過get和set訪問器對其訪問。

// 定義Pointstruct Point{    var x = 0.0,y = 0.0}// 定義Sizestruct Size{    var width = 0.0,height = 0.0}// 定義Rectstruct Rect{    var origin = Point()    var size = Size()    var center:Point{    get{        let centerX = origin.x + (size.width / 2)        let centerY = origin.y + (size.height / 2)        return Point(x:centerX,y:centerY)    }    set(newCenter){        origin.x = newCenter.x - (size.width / 2)        origin.y = newCenter.y - (size.height / 2)    }    }}var square = Rect(origin:Point(x:0.0,y:0.0),size:Size(width:10.0,height:20.0))let initialSquareCenter = square.centersquare.center = Point(x:15.0,y:15.0)println("square origin is now at (/(square.origin.x),/(square.origin.y))")

16.4.屬性觀察者

　　為了監聽屬性的變化，swift通過了屬性觀察者。

willset觀察者是在存儲之前調用；
didSet新值存儲后調用。

class StepCounter{    var totalSteps:Int = 0{    willSet(newTotalSteps){        println("About to set totalSteps to /(newTotalSteps)")    }    didSet{        if totalSteps >= oldValue{            println("Added /(totalSteps - oldValue) steps")        }    }    }}let stepCounter = StepCounter()stepCounter.totalSteps = 200stepCounter.totalSteps = 360

16.5.靜態屬性

　　靜態屬性在結構體中使用static定義，類中使用class定義。

struct SomeStructure{    static var storedTypeProperty = "Some Value"}class SomeClass{    class var computedTypeProperty:Int{        return 3    }}

17.方法

　　Swift中的方法是與特定類型(類和結構體)相關的函數

17.1.方法

class Counter{    var count = 0    func increment(){        count++    }    func incremmentBy(amount:Int){        count += amount    }    func reset(){        count = 0    }}let counter = Counter()counter.increment()counter.incremmentBy(5)counter.reset()

17.2.使用self

　　self代表當前對象。

struct Point{    var x = 0.0,y = 0.0    func isToTheRightOfX(x:Double) -> Bool{        return self.x > x    }}let somePoint = Point(x:4.0,y:5.0)if somePoint.isToTheRightOfX(1.0){    println("This point is to the right of the line where x == 1.0")}

18.下標

18.1.定義下標

　　還記得字典嗎？

var numberOfLegs = ["bird":2,"cat":4,"ant":6]let birdLeg = numberOfLegs["bird"]

　　["bird"]就是下標

　　下標可以在類和結構體中定義

18.2.只讀下標

struct TimesTable{    let multiplier:Int    subscript(index:Int) -> Int{        return multiplier * index    }}let threeTimesTable = TimesTable(multiplier:3)println("six times three is /(threeTimesTable[6])")

19.繼承

　　Swift中的類能夠繼承其他類的屬性、方法等。

19.1.定義基類

class Vehicle{    var numberOfWheels:Int    var maxPassengers:Int    func description() -> String{        return "/(numberOfWheels) wheels;up to /(maxPassengers)"    }    init(){        numberOfWheels = 0        maxPassengers = 1    }}let someVehicle = Vehicle()

19.2.定義子類

class Bicycle:Vehicle{    init() {        super.init()        numberOfWheels = 2    }}let bicycle = Bicycle()println("Bicycle:/(bicycle.description())")

19.3.重寫(Overriding)

　　子類能夠重寫父類的方法、屬性、下標。

19.3.1方法重寫

class Vehicle{    var numberOfWheels:Int    var maxPassengers:Int    func description() -> String{        return "/(numberOfWheels) wheels;up to /(maxPassengers)"    }    init(){        numberOfWheels = 0        maxPassengers = 1    }}class Car:Vehicle{    var speed:Double = 0.0    init() {        super.init()        numberOfWheels = 4        maxPassengers = 5    }    override func description() -> String{        return super.description() + ";" + "traveling at /(speed)"    }}let car = Car()println("Car:/(car.description())")

19.3.2屬性重寫

class Vehicle{    var numberOfWheels:Int    var maxPassengers:Int    func description() -> String{        return "/(numberOfWheels) wheels;up to /(maxPassengers)"    }    init(){        numberOfWheels = 0        maxPassengers = 1    }}class Car:Vehicle{    var speed:Double = 0.0    init() {        super.init()        numberOfWheels = 4        maxPassengers = 5    }    override func description() -> String{        return super.description() + ";" + "traveling at /(speed)"    }}class SpeedLimitedCar:Car{    override var speed:Double{    get{        return super.speed    }    set{        super.speed = min(newValue,40.0)    }    }}let limitedCar = SpeedLimitedCar()limitedCar.speed = 60.0println("SpeedLimitedCar:/(limitedCar.description())")

20.構造器(Initializer)

　　為了初始化結構體和類等類型的實例屬性。

20.1.默認構造器

struct Fahrenheit{    var temperature:Double    init(){        temperature = 32.0    }}var f = Fahrenheit()  // 調用默認構造器init()，沒有參數和返回值println("The default temperature is /(f.temperature)")

20.2.自定義構造器

　　定義類兩個構造器：init(fromFahrenheit:) 和 init(fromKelvin:)

struct Celsius{    var temperatureInCelsius:Double    init(fromFahrenheit fahrenheit:Double){        temperatureInCelsius = (fahrenheit - 32.0) / 1.8    }    init(fromKelvin kelvin:Double){        temperatureInCelsius = kelvin - 273.15    }//    init(fahrenheit:Double){//        temperatureInCelsius = (fahrenheit - 32.0) / 1.8//    }//    //    init(kelvin:Double){//        temperatureInCelsius = kelvin - 273.15//    }}let boilingPointOfWater = Celsius(fromFahrenheit:212.0)let freezingPointOfWater = Celsius(fromKelvin:273.15)//let boilingPointOfWater = Celsius(fahrenheit:212.0)//let freezingPointOfWater = Celsius(kelvin:273.15)

21.析構器(Deinitializer)

　　析構器與構造器相反，在對象釋放時候調用。

　　使用關鍵字deinit，語法如下：

deinit{}

　　實例：

class Player{    var coinsInPurse:Int    init(coins:Int){        println("call init")        coinsInPurse = coins    }    func winCoins(coins:Int){        coinsInPurse += 10    }    deinit{        coinsInPurse = 0    }}var playerOne:Player? = Player(coins:100)println("PlayerOne has coins /(playerOne!.coinsInPurse)")playerOne = nil;

22.擴展(Extension)

　　在現有類和結構體的基礎上，擴展新的功能。

　　語法：

extension SomeType{}extension SomeType:SomeProtocol,AnotherProtocol{}

　　OC中的擴展：

@interface UIImage (UIImageScale)

22.1.計算屬性

extension Double{    var km:Double{return self * 1000.0}    var m:Double{return self}    var cm:Double{return self / 100.0}    var mm:Double{return self / 1000.0}}let oneInch = 25.4.mmprintln("OneInch is /(oneInch) meters")

22.2.使用構造器

struct Size{    var width = 0.0,height = 0.0}struct Point{    var x = 0.0,y = 0.0}struct Rect{    var origin = Point()    var size = Size()}extension Rect{    init(center:Point,size:Size){        let originX = center.x - (size.width / 2)        let originY = center.y - (size.height / 2)        self.init(origin:Point(x:originX,y:originY),size:size)    }}let centerRect = Rect(center:Point(x:4.0,y:4.0),size:Size(width:3.0,height:3.0))

22.3.方法擴展

extension Int{    func message() -> String{        var message = "";        switch self{        case 0:            message = "成功"        case -1:            message = "用戶登錄失敗"        default:            message = "未知錯誤"        }        return message;    }}3.message();0.message();(-1).message();

23.協議(Protocol)

　　協議是為方法、屬性等定義一套規范，沒有具體的實現。協議能夠被類、結構體等具體實現。

protocol SomeProtocol{}struct SomeStructure:SomeProtocol{}class SomeClass:SomeProtocol{}

23.1.屬性

// 1.set和get訪問器protocol SomeProtocol{    var mustBeSettable:Int{get set}    var doesNotNeedToBeSettable:Int{get}}// 2.靜態屬性protocol AnotherProtocol{    class var someTypeProperty:Int{get set}}// 3.只讀protocol FullyNamed{    var fullName:String{get}}

　　示例：

protocol FullyNamed{    var fullName:String{get}}struct Person : FullyNamed{    var fullName:String}let john = Person(fullName:"John Appleseed")class Starship : FullyNamed{    var prefix:String?    var name:String    init(name:String,prefix:String? = nil){        self.name = name        self.prefix = prefix    }    var fullName:String{    return (prefix ? prefix! + " " : "") + name    }}var ncc1701 = Starship(name:"Enterprise",prefix:"USS")println("/(ncc1701.fullName)")

23.2.方法

// 1.定義方法protocol RandomNumberGenerator{    func random() -> Double}// 2.定義靜態方法protocol SomeProtocol{    class func someTypeMethod()}

　　示例：

class LinearCongruentialGenerator:RandomNumberGenerator{    var lastRandom = 42.0    let m = 139968.0    let a = 3877.0    let c = 29573.0    func random() -> Double{        lastRandom = ((lastRandom * a + c) % m)        return lastRandom / m    }}let generator = LinearCongruentialGenerator()println("Here's a random number:/(generator.random())")

23.3.把協議作為類型使用

protocol RandomNumberGenerator{    func random() -> Double}class LinearCongruentialGenerator:RandomNumberGenerator{    var lastRandom = 42.0    let m = 139968.0    let a = 3877.0    let c = 29573.0    func random() -> Double{        lastRandom = ((lastRandom * a + c) % m)        return lastRandom / m    }}class Dice{    let sides:Int    let generator:RandomNumberGenerator    init(sides:Int,generator:RandomNumberGenerator){        self.sides = sides        self.generator = generator    }    func roll() -> Int{        return Int(generator.random() * Double(sides)) + 1    }}var d6 = Dice(sides:6,generator:LinearCongruentialGenerator())for _ in 1...5{    println("Random dice roll is /(d6.roll())")}

24.Swift的應用

　　在這一部分，我實現了一個小Demo：導航欄和Tab欄結合使用。具體代碼說明如下：

24.1.項目結構說明

　　主要文件說明：

AppDelegate：系統委托類；
TabBarViewController：Tab欄管理類；
CustomNavigationController：自定義的導航欄類，在這個類里面，做了4英寸屏和3.5英寸屏的處理；
ViewController文件夾：具體的頁面控制器；
NSStringExt：對String類型的擴展，主要是IOS7的判斷、根據字符串長度返回在控件中顯示的高度(常用于UITableViewCell中自適應調整Cell的高度使用)；
.......

24.2.運行效果截圖

　　iPhone 5S截圖：

　　iPhone 4S截圖：

24.3.主要代碼

　　AppDelegate里面：

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool    {        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)                var tabbarViewCtrl = TabBarViewController(nibName:nil,bundle:nil);//        var navigationViewController = UINavigationController(rootViewController:tabbarViewCtrl);                var navigationViewController = CustomNavigationController(rootViewController: tabbarViewCtrl);        self.window!.rootViewController = navigationViewController;                self.window!.makeKeyAndVisible()        return true    }

　　TabBarViewController：

    init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?)    {        super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)                self.title = "任務";    }    override func viewDidLoad()    {        super.viewDidLoad()        configureTabBar();    }    override func didReceiveMemoryWarning()    {        super.didReceiveMemoryWarning()        // Dispose of any resources that can be recreated.    }        /*******************************************************************************    * 方法名稱：configureTabBar    * 功能描述：配置TabBar控件    * 輸入參數：    * 輸出參數：    ******************************************************************************/    func configureTabBar()    {        self.view.backgroundColor = UIColor.whiteColor();        self.tabBar.hidden = true;  // 隱藏自帶的Tab        var width = self.view.frame.size.width;        var height = self.view.frame.size.height;                self.myTabbar = UIView(frame:CGRectMake(0, height - 48 - 64, width, 112));        let currentVersion = UIDevice.currentDevice().systemVersion;                if (currentVersion.isIos7())        {            self.myTabbar!.frame = CGRectMake(0, height - 48, width, 112);        }        self.myTabbar!.backgroundColor = UIColor(patternImage:UIImage(named:"tab_bg_ico.png"));        self.view.addSubview(self.myTabbar);        self.view.bringSubviewToFront(self.myTabbar);                // 任務        var btnTask = UIButton.buttonWithType(UIButtonType.Custom) as UIButton;  // 后面必須要加上as UIButton        btnTask.frame = CGRectMake(0, 0, 80, 48);        btnTask.tag = 100;        btnTask.selected = true;        btnTask.setImage(UIImage(named:"tabtask_sel_ico.png"),forState:UIControlState.Normal);        btnTask.addTarget(self,action: "tabBarButtonClicked:",forControlEvents:UIControlEvents.TouchUpInside);        self.myTabbar!.addSubview(btnTask);                // 單據        var btnBill = UIButton.buttonWithType(UIButtonType.Custom) as UIButton;        btnBill.frame = CGRectMake(80, 0, 80, 48);        btnBill.tag = 101;        btnBill.setImage(UIImage(named:"tabbill_nor_ico.png"),forState:UIControlState.Normal);        btnBill.addTarget(self,action: "tabBarButtonClicked:",forControlEvents:UIControlEvents.TouchUpInside);        self.myTabbar!.addSubview(btnBill);                // 查詢        var btnQuery = UIButton.buttonWithType(UIButtonType.Custom) as UIButton;        btnQuery.frame = CGRectMake(160, 0, 80, 48);        btnQuery.tag = 102;        btnQuery.setImage(UIImage(named:"tabquery_nor_ico.png"),forState:UIControlState.Normal);        btnQuery.addTarget(self,action: "tabBarButtonClicked:",forControlEvents:UIControlEvents.TouchUpInside);        self.myTabbar!.addSubview(btnQuery);                // 設置        var btnSetting = UIButton.buttonWithType(UIButtonType.Custom) as UIButton;        btnSetting.frame = CGRectMake(240, 0, 80, 48);        btnSetting.tag = 103;        btnSetting.setImage(UIImage(named:"tabset_nor_ico.png"),forState:UIControlState.Normal);        btnSetting.addTarget(self,action:"tabBarButtonClicked:",forControlEvents:UIControlEvents.TouchUpInside);        self.myTabbar!.addSubview(btnSetting);                var taskViewCtrl = MyTaskViewController(nibName:"MyTaskViewController",bundle:nil);        var billViewCtrl = MyBillViewController();        var queryViewCtrl = QueryViewController(nibName:"QueryViewController",bundle:nil);        var settingViewCtrl = SettingViewController(nibName:"SettingViewController",bundle:nil);                self.viewControllers = [taskViewCtrl,billViewCtrl,queryViewCtrl,settingViewCtrl];    }        /*******************************************************************************    * 方法名稱：configureTabBar    * 功能描述：配置TabBar控件    * 輸入參數：        sender:事件源    * 輸出參數：    ******************************************************************************/    func tabBarButtonClicked(sender:UIButton)    {        var index       = sender.tag;        var btnTask     = self.view.viewWithTag(100) as UIButton        var btnBill     = self.view.viewWithTag(101) as UIButton        var btnQuery    = self.view.viewWithTag(102) as UIButton        var btnSetting  = self.view.viewWithTag(103) as UIButton                switch index{            case 100:  // 任務                self.title = "任務";                btnTask.selected    = true;                btnBill.selected    = false;                btnQuery.selected   = false;                btnSetting.selected = false;                btnTask.setImage(UIImage(named:"tabtask_sel_ico.png"),forState:UIControlState.Normal);                btnBill.setImage(UIImage(named:"tabbill_nor_ico.png"),forState:UIControlState.Normal);                btnQuery.setImage(UIImage(named:"tabquery_nor_ico.png"),forState:UIControlState.Normal);                btnSetting.setImage(UIImage(named:"tabset_nor_ico.png"),forState:UIControlState.Normal);            case 101:  // 單據                self.title = "單據";                btnTask.selected    = false;                btnBill.selected    = true;                btnQuery.selected   = false;                btnSetting.selected = false;                btnTask.setImage(UIImage(named:"tabtask_nor_ico.png"),forState:UIControlState.Normal);                btnBill.setImage(UIImage(named:"tabbill_sel_ico.png"),forState:UIControlState.Normal);                btnQuery.setImage(UIImage(named:"tabquery_nor_ico.png"),forState:UIControlState.Normal);                btnSetting.setImage(UIImage(named:"tabset_nor_ico.png"),forState:UIControlState.Normal);            case 102:  // 查詢                self.title = "查詢";                btnTask.selected    = false;                btnBill.selected    = false;                btnQuery.selected   = true;                btnSetting.selected = false;                btnTask.setImage(UIImage(named:"tabtask_nor_ico.png"),forState:UIControlState.Normal);                btnBill.setImage(UIImage(named:"tabbill_nor_ico.png"),forState:UIControlState.Normal);                btnQuery.setImage(UIImage(named:"tabquery_sel_ico.png"),forState:UIControlState.Normal);                btnSetting.setImage(UIImage(named:"tabset_nor_ico.png"),forState:UIControlState.Normal);            case 103:  // 設置                self.title = "設置";                btnTask.selected    = false;                btnBill.selected    = false;                btnQuery.selected   = false;                btnSetting.selected = true;                btnTask.setImage(UIImage(named:"tabtask_nor_ico.png"),forState:UIControlState.Normal);                btnBill.setImage(UIImage(named:"tabbill_nor_ico.png"),forState:UIControlState.Normal);                btnQuery.setImage(UIImage(named:"tabquery_nor_ico.png"),forState:UIControlState.Normal);                btnSetting.setImage(UIImage(named:"tabset_sel_ico.png"),forState:UIControlState.Normal);            default:                println("No Selected Items");        }                self.selectedIndex = index - 100;    }

　　CustomNavigationController：

class CustomNavigationController: UINavigationController{    init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?)    {        super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)        // Custom initialization    }        init(rootViewController: UIViewController!)    {        return super.init(rootViewController: rootViewController);    }    override func viewDidLoad()    {        super.viewDidLoad()                let currentVersion = UIDevice.currentDevice().systemVersion;        if (currentVersion.isIos7())        {            self.navigationBar.setBackgroundImage(UIImage(named:"navbg_ico.png").stretchableImageWithLeftCapWidth(20,topCapHeight: 30),forBarMetrics:UIBarMetrics.Default);        }        else        {            self.navigationBar.setBackgroundImage(UIImage(named:"navbg_ico.png"),forBarMetrics:UIBarMetrics.DefaultPrompt);        }    }    override func didReceiveMemoryWarning()    {        super.didReceiveMemoryWarning()        // Dispose of any resources that can be recreated.    }        override func pushViewController(viewController: UIViewController!, animated: Bool)    {        super.pushViewController(viewController,animated:animated);    }        override func popViewControllerAnimated(animated: Bool) -> UIViewController!    {        return super.popViewControllerAnimated(animated);    }}

　　MyTaskViewController

    override func viewDidLoad()    {        super.viewDidLoad()        self.tableView.registerClass(UITableViewCell.self,forCellReuseIdentifier: "Cell");    }        override func viewWillAppear(animated: Bool)    {        var width = self.view.frame.size.width        var height = self.view.frame.size.height                self.tableView.frame = CGRectMake(0, 0, width, height - 48);    }    override func didReceiveMemoryWarning()    {        super.didReceiveMemoryWarning()        // Dispose of any resources that can be recreated.    }        // =========================================================================    // Table view data source        func numberOfSectionsInTableView(tableView: UITableView!) -> Int    {        return 1;    }        func tableView(tableView: UITableView!, numberOfRowsInSection section: Int) -> Int    {        return 50;    }        func tableView(tableView: UITableView!, heightForRowAtIndexPath indexPath: NSIndexPath!) -> CGFloat    {        return 56;    }        func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell!    {        let cell = tableView .dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as UITableViewCell;        var lblBillCode = UILabel(frame:CGRectMake(10,4,140,22));        lblBillCode.text = "JTBX1404020601";        lblBillCode.font = UIFont(name: "Arial",size: 16);                cell.addSubview(lblBillCode);        var lblContent = UILabel(frame:CGRectMake(160,4,150,22));        lblContent.text = "市內交通費用報銷單";        lblContent.textAlignment = NSTextAlignment.Right;        lblContent.font = UIFont(name: "Arial",size: 16);        cell.addSubview(lblContent);                var lblTime = UILabel(frame:CGRectMake(160,30,150,22));        lblTime.text = "2014-05-23 22:10:10";        lblTime.font = UIFont(name: "Arial",size: 14);        lblTime.textColor = UIColor.grayColor();        lblTime.textAlignment = NSTextAlignment.Right;        cell.addSubview(lblTime);        return cell;    }        // =========================================================================    // Table view data delegate        func tableView(tableView: UITableView!, didSelectRowAtIndexPath indexPath: NSIndexPath!){        println("row = %d",indexPath.row)    }

　　NSStringExt：

extension String {        /*******************************************************************************    * 方法名稱：isIos7    * 功能描述：配置TabBar控件    * 輸入參數：    * 輸出參數：true:IOS7及以上系統;false:IOS7以下系統。    ******************************************************************************/    func isIos7() -> Bool?    {        return self >= "7.0"    }        func stringHeightWith(fontSize:CGFloat,width:CGFloat)->CGFloat    {        var font = UIFont.systemFontOfSize(fontSize)        var size = CGSizeMake(width,CGFLOAT_MAX)        var paragraphStyle = NSMutableParagraphStyle()        paragraphStyle.lineBreakMode = .ByWordWrapping;        var  attributes = [NSFontAttributeName:font,            NSParagraphStyleAttributeName:paragraphStyle.copy()]                var text = self as NSString        var rect = text.boundingRectWithSize(size, options:.UsesLineFragmentOrigin, attributes: attributes, context:nil)        return rect.size.height    }}