//输出
println("Hello, world”)
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//var定义变量 let定义常量
var myVariable = 42
myVariable = 50
let myConstant = 42
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//定义常量或变量的时候指定类型
let implicitInteger = 70
let implicitDouble = 70.0
let explicitDouble: Double = 70
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//定义字符串
let label = "The width is “
let width = 94
let widthLabel = label + String(width)
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//在字符串中添加值
let apples = 3
let oranges = 5
let appleSummary = "I have \(apples) apples”
let fruitSummary = “I have \(apples + oranges) pieces of fruit.”
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//创建字典和数组
var shoppingList = ["catfish","water", "tulips","blue paint”]
shoppingList[1] = "bottle of water”
var occupations = [
"Malcolm": "Captain”,
"Kaylee": "Mechanic”,
]
occupations["Jayne”] = "Public Relations”
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//创建空数组和空字典
let emptyArray = String[]()
let emptyDictionary = Dictionary<String, Float>()
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//for in 语句
let individualScores = [75, 43, 103, 87, 12]
for index in individualScores {
println("\(index) times 5 is \(index * 5)")
}
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let numberOfLegs = ["spider": 8, "ant": 6, "cat": 4]
for (animalName, legCount) in numberOfLegs {
println("\(animalName)s have \(legCount) legs")
}
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for character in "Hello" {
println(character)
}
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//for循环
for var index = 0; index < 3; ++index {
println("index is \(index)")
}
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//while
var square = 0
var diceRoll = 0
while square < finalSquare {
// roll the dice
if ++diceRoll == 7 { diceRoll = 1 }
// move by the rolled amount
square += diceRoll
if square < board.count {
// if we're still on the board, move up or down for a snake or a ladder
square += board[square]
}
}
println("Game over!")
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//if else
temperatureInFahrenheit = 90
if temperatureInFahrenheit <= 32 {
println("It's very cold. Consider wearing a scarf.")
} else if temperatureInFahrenheit >= 86 {
println("It's really warm. Don't forget to wear sunscreen.")
} else {
println("It's not that cold. Wear a t-shirt.")
}
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//switch case
64
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//问号 感叹号
！告诉编译器这个变量绝对不为nil，当为nil的时候会报错
？告诉编译器这个变量可能为nil，当为nil的时候不会报错
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//创建单例
import UIKit
class DataCenter: NSObject {
class let dataCenterObj:DataCenter = DataCenter()
class func getDataCenter() ->DataCenter {
return dataCenterObj
}
}
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6.协议（Protocols）
语法:
在Objective-C中我们这么声明Protocol:
| 123 | @protocol SampleProtocol``- (void)someMethod;``@end |
|---|
而在Swift中：
| 1234 | protocol SampleProtocol ``{`` func someMethod()``} |
|---|
在Swift遵循协议:
| 1234 | class AnotherClass: SomeSuperClass, SampleProtocol``{`` func someMethod() {}``} |
|---|
那么之前Objective-C的protocol中,我们可以标志optional。那在Swift中呢？
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遗憾的是,目前纯Swift的protocol还不支持optional。但根据苹果官方论坛的一位员工的回答,未来Swift是会支持的。
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