swift 2

...

..<

func a(inout a)  //by ref  use &xx

Parameters passed to functions are constants by default, which means they can't be modified.

func incrementAndPrint(var value: Int) {  //var  可修改，传值
  value++
  print(value)
}

Closure

var multiplyClosure: (Int, Int) -> Int

multiplyClosure = { (a: Int, b: Int) -> Int in
return a * b

}

multiplyClosure = { (a, b) in
a*b

}

multiplyClosure = {
$0 * $1 }

if you are using an optional type then you know you must handle the nil case

optional

let binding

Nil coalescing ??

计算属性可以用于类、结构体和枚举里,存储属性只能用于类和结构体

使用关键字 static 来定义值类型的类型属性,关键字 class 来为类(class)定义类型属性

@objc 可以让你的 Swift API 在 Objective-C