1、簡(jiǎn)單值
let聲明常量漓穿，var聲明變量嗤军。
var myVariable = 42
myVariable = 50
let myConstant = 42
值永遠(yuǎn)不會(huì)被隱式轉(zhuǎn)換為其他類型
值轉(zhuǎn)換成String的兩種方式：\(value)、String(value)
let apples = 3
let appleSummary = "I have \(apples) apples."
創(chuàng)建一個(gè)空數(shù)組或者字典的語(yǔ)法
let emptyArray = String[]()
let emptyDictionary = Dictionary<String, Float>()
2晃危、控制流
switch支持任意類型的數(shù)據(jù)以及各種比較操作——不僅僅是整數(shù)以及測(cè)試相等
let vegetable = "red pepper"
switch vegetable {
case "celery":
let vegetableComment = "Add some raisins and make ants on a log."
case "cucumber", "watercress":
let vegetableComment = "That would make a good tea sandwich."
case let x where x.hasSuffix("pepper"):
let vegetableComment = "Is it a spicy \(x)?"
default:
let vegetableComment = "Everything tastes good in soup."
}
在循環(huán)中使用..(不包含上界)`...`(包含上界)來(lái)表示范圍
var firstForLoop = 0
for i in 0..3 {
firstForLoop += i
}
3叙赚、函數(shù)和閉包
使用func來(lái)聲明一個(gè)函數(shù)老客，使用名字和參數(shù)來(lái)調(diào)用函數(shù)。使用->來(lái)指定函數(shù)返回值震叮。
func greet(name: String, day: String) -> String {
return "Hello \(name), today is \(day)."
}
greet("Bob", "Tuesday")
函數(shù)實(shí)際上是一種特殊的閉包胧砰，你可以使用 {} 來(lái)創(chuàng)建一個(gè)匿名閉包。使用 in 來(lái)分割參數(shù)并返回類型苇瓣。
numbers.map({
(number: Int) -> Int in
let result = 3 * number
return result
})
4尉间、對(duì)象和類
使用class和類名來(lái)創(chuàng)建一個(gè)類。類中屬性的聲明和常量钓简、變量聲明一樣乌妒，唯一的區(qū)別就是它們的上下文是類。同樣外邓，方法和函數(shù)聲明也一樣撤蚊。
class Shape {
var numberOfSides = 0
func simpleDescription() -> String {
return "A shape with \(numberOfSides) sides."
}
}
要?jiǎng)?chuàng)建一個(gè)類的實(shí)例，在類名后面加上括號(hào)损话。使用點(diǎn)語(yǔ)法來(lái)訪問(wèn)實(shí)例的屬性和方法侦啸。
var shape = Shape()
shape.numberOfSides = 7
var shapeDescription = shape.simpleDescription()
使用init來(lái)創(chuàng)建一個(gè)構(gòu)造函數(shù)，使用deinit創(chuàng)建一個(gè)析構(gòu)函丧枪，子類如果要重寫(xiě)父類的方法的話光涂，需要用override標(biāo)記
處理變量的可選值時(shí)，你可以在操作（比如方法拧烦、屬性和子腳本）之前加?忘闻。如果?之前的值是nil，?后面的東西都會(huì)被忽略恋博，并且整個(gè)表達(dá)式返回nil齐佳。否則，?之后的東西都會(huì)被運(yùn)行债沮。在這兩種情況下炼吴，整個(gè)表達(dá)式的值也是一個(gè)可選值。
let optionalSquare: Square? = Square(sideLength: 2.5, name: "optional square")
let sideLength = optionalSquare?.sideLength
5疫衩、枚舉和結(jié)構(gòu)體
使用enum來(lái)創(chuàng)建一個(gè)枚舉硅蹦，使用struct來(lái)創(chuàng)建一個(gè)結(jié)構(gòu)體。
enum Rank: Int {
case Ace = 1
case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten
case Jack, Queen, King
func simpleDescription() -> String {
switch self {
case .Ace:
return "ace"
case .Jack:
return "jack"
case .Queen:
return "queen"
case .King:
return "king"
default:
return String(self.toRaw())
}
}
}
let ace = Rank.Ace
let aceRawValue = ace.toRaw()
6闷煤、接口和擴(kuò)展
使用protocol來(lái)聲明一個(gè)接口童芹，使用extension來(lái)為現(xiàn)有的類型添加功能
7、數(shù)組的subArray
let array = ["aaa", "bbb", "ccc", "ddd", "eee"]
let subArr1 = array[0 ... 2] // ["aaa", "bbb", "ccc"]
let subArr2 = array[1 ..< 3] // ["bbb", "ccc"]
let subArr3 = array.prefix(3) // ["aaa", "bbb", "ccc"]
let subArr4 = array.suffix(3) // ["ccc", "ddd", "eee"]
let subArray1 = Array(subArr1) // subArr1是ArraySlice型鲤拿，需轉(zhuǎn)為Array
8辐脖、模式匹配
let age = 19
if 18...25 ~= age {
print("條件滿足")
}
等價(jià)于
if case 18...25 = age {
print("條件滿足")
}
等價(jià)于
if age >= 18 && age <= 25 {
print("條件滿足")
}
9、部分圓角
func cornerImage(frame: CGRect, image: UIImage, Radii: CGSize) -> UIImageView {
let imageView = UIImageView(image: image)
imageView.frame = frame
let bezierPath = UIBezierPath(roundedRect: imageView.bounds, byRoundingCorners: [.topLeft, .topRight], cornerRadii: Radii)
let shapeLayer = CAShapeLayer()
shapeLayer.path = bezierPath.cgPath
imageView.layer.mask = shapeLayer
return imageView
}
