swift init 初始化
class PropertiesClass1 { var a = "Stringa" init() { print("初始化") } } class PropertiesClass2 { var id = 0 //lazy 懒加载,只有使用的时候才触发 lazy var properties1 = PropertiesClass1() //初始化必须全部初始化所有属性,或者为Options var name: String? //geter seter var qq: String { //geter seter 里面不能使用自己属性,否则会死循环 get { return self.name! } set { self.name = newValue } } //只读属性 var height: Int { return 180 } var address: String = "xxx" { willSet { print(" 新值\(newValue)") } didSet { print("旧值 \(oldValue)") } } var function_properties = {return "properties"}() } var properties2 = PropertiesClass2() print(properties2.properties1) properties2.qq = "65683264" print(properties2.qq) print(properties2.height) // properties2.height = 2 properties2.address = "ca" print(properties2.function_properties)