☔ 保护代理模式(结构型模式)
在代理模式中，创建一个类代表另一个底层类的功能。
保护代理用于限制访问。
示例：
protocol DoorOpening {
func open(doors: String) -> String
}
final class HAL9000: DoorOpening {
func open(doors: String) -> String {
return ("HAL9000: Affirmative, Dave. I read you. Opened \(doors).")
}
}
final class CurrentComputer: DoorOpening {
private var computer: HAL9000!
func authenticate(password: String) -> Bool {
guard password == "pass" else {
return false
}
computer = HAL9000()
return true
}
func open(doors: String) -> String {
guard computer != nil else {
return "Access Denied. I'm afraid I can't do that."
}
return computer.open(doors: doors)
}
}用法
let computer = CurrentComputer()
let podBay = "Pod Bay Doors"
computer.open(doors: podBay)
computer.authenticate(password: "pass")
computer.open(doors: podBay)