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  • Swift可选链

    //可选链测试
    
    class Person{
    
        var residence:Residence!
    
        var name:String
    
        init(name:String){
    
            self.name = name
    
        }
    
    }
    
    ///住宅
    
    class Residence {
    
        var residenceNum = 101
    
    }
    
     
    
    var lucy = Person(name: "Lucy")
    
    //没有为lucy初始化住宅
    
    if let roomNumber1 = lucy.residence?.residenceNum {
    
        print("(lucy.name)有住宅,住宅号是(roomNumber1)")
    
    }else{
    
        print("(lucy.name)没有住宅")
    
    }
    
     
    
    var lily = Person(name: "Lily")
    
    lily.residence = Residence()
    
    if let roomNumber2 = lily.residence?.residenceNum {
    
        print("(lily.name)有住宅,住宅号是(roomNumber2)")
    
    }else{
    
        print("(lily.name)没有住宅")
    
    }
    

    //1.可选链的访问方式:将强制解析的感叹号换成?,在隐式解析的后面也添加?后缀

    //2.可选链会自动判断程序访问的关联实例是否为nil

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  • 原文地址:https://www.cnblogs.com/sweetXiaoma/p/5532233.html
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