一、常量与变量
var testVariable = 42
testVariable = 50
println(testVariable)
let testLet = 30
println("Hello world!")
二、命名规则
let doubleNum:Double = 2.1
var π = 3.14
var 任海瑞 = "iOS"
let ?? = 123
let cat = "??"
println(??)
println(cat)
let int1 = 17
let int2 = 0b0001
let int3 = 0o21
let int4 = 0x11
let minValue = UInt8.min
let maxValue = UInt8.max
println(minValue,maxValue)
三、类型别名 typealias
typealias NSInteger = Int
var value:NSInteger = 45
value = 12
println(value)
var enable:Bool = true
var tigerIsAnimal = false
let label = "The width is "
let width = 56
四、Playground
五、Array
// 不支持隐式类型转换
// 相同类型相加
var widthLabel = label + String(width)
widthLabel += "!"
println(widthLabel)
let apple = 3
let oranges = 5
let applesSummary = "I have \(apple + oranges) apples"
println(applesSummary)
var shoppingList = ["芒果","橘子","葡萄"]
println(shoppingList.capacity)
// 增加元素
shoppingList.append("香蕉")
shoppingList.insert("苹果", atIndex: 0)
//shoppingList += "柚子"
shoppingList += ["西瓜","木瓜","杨桃"]
println(shoppingList)
println(shoppingList.count)
println(shoppingList.capacity)
shoppingList[0] = "哈密瓜"
println(shoppingList)
shoppingList[4...7] = ["Bananas","Apples"] // 把4.5.6.7下标元素换成
// 除了能改变元素以外，还会改变元素个数
println(shoppingList)
// 删除
shoppingList.removeLast()
println(shoppingList)
shoppingList.removeAtIndex(4)
// 数据的遍历
for item in shoppingList
{
println(item)
}
// 遍历2
for (index,value)in enumerate(shoppingList)
{
println("Item \(index+1):\(value)")
}
var threeDoubles = [Double](count: 3, repeatedValue: 0.0)
var anotherDoubles = Array(count: 3, repeatedValue: 2.5)
println(threeDoubles)
println(anotherDoubles)
var sixDoubles = threeDoubles + anotherDoubles
println(sixDoubles)
六、Dictionary
let emptyDictionary = [:]
let emptyDic = Dictionary<String,Float>()
var airports = ["TYO":"Tokyo","DUB":"Dublin"]
println(airports)
// 添加和修改字典
airports["TYO"] = "Tokyo International"
println(airports)
// 假如没有找到这个key 就要添加一对
airports["LHR"] = "London"
println(airports)
// delete
airports["LHR"] = nil
println(airports)
// airports.removeValueForKey("TYO")
println("airports count is " + String(airports.count))
println("airports count is \(airports.count)")
// 遍历
for (key,value) in airports
{
println("\(key):\(value)")
}
// 遍历所有的key
for key in airports.keys
{
println(key)
}
let allKeys = airports.keys.array
println(allKeys)
七、Tuple
// Tuple元组 ：任意数据类型的容器，常作为函数返回值
let (x,y) = (1,2)
let http404Error = (404,"Not Found")
let (statusCode,statusMessage) = http404Error
// 下划线— 忽略不需要的元素
let (justTheStatusCode,_) = http404Error
// 直接访问
println("just is \(justTheStatusCode)")
// 类似于字典 用key
println("status is \(x)")
// 用序号index
println("status code is \(http404Error.0)")
let http200Status = (statusCode:200,desc:"OK")
println("http200: \(http200Status.statusCode)")
八、optional
// Optional 要么不存在 要么等于X
var serverResponseCode :Int? = 404
let possibleNumber = "123"
let converNumber: Int? = possibleNumber.toInt()
// 假如是123可以转换成int，则存在，假如是Hello 就没办法转换成int 也就不存在了
println(converNumber?.description)
// nil 不能用与 非可选类型
// 假设代码中有变量或常量 可能不存在 ，就要声明成恰当的可选类型。如果定义的可选的类型对象不提供默认值，则该对象自动设为nil
var strValue : String?
var strTest : String? = "hello"
let hashValue = strValue?.hashValue
println(hashValue)
println(strTest?.hashValue)
/*
总结 ？使用场景
1、声明optional变量
2、optional值操作中，判断是否操作。
*/
声明UI 代码的时候会用
var window: UIWindow?
九、解包 ！
self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
self.window!.backgroundColor = UIColor.greenColor()
var rootViewController = RootViewController()
var rootNavigationController = UINavigationController(rootViewController: rootViewController)
self.window!.rootViewController = rootNavigationController
let possibleString: String? = "an optional string"
println(possibleString!)// 解包，确定一定存在值。
let possibleString:String? = "An optional string"
let stringVale = possibleString!.hashValue
// 这种方法叫选择绑定
if let sValue = possibleString
{
let stringValue = sValue.hashValue
}
十、隐式解包的可选类型
代码很多的话，可选类型 每次都要写感叹号 ！ 不方便
定义的时候 直接把问号改成感叹号
隐式解包的可选类型：自动解包的可选类型，用在：定义常量变量，定义完成后一定会存在的情况 主要是用在类的初始化过程中。
let assumedString: String! = "an test string"
println(assumedString)
println(assumedString.hashValue)
总结！使用场景
1、强制对 可选类型进行解包
2、声明 隐士解包的可选类型 类的属性