? 虚拟代理(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。
虚拟代理用于对象的需时加载。
示例：
protocol HEVSuitMedicalAid {
func administerMorphine() -> String
}
final class HEVSuit: HEVSuitMedicalAid {
func administerMorphine() -> String {
return "Morphine administered."
}
}
final class HEVSuitHumanInterface: HEVSuitMedicalAid {
lazy private var physicalSuit: HEVSuit = HEVSuit()
func administerMorphine() -> String {
return physicalSuit.administerMorphine()
}
}用法
let humanInterface = HEVSuitHumanInterface()
humanInterface.administerMorphine()