类中有常量,并定义可失败构造器,报错
class TeachSchool
{
var name : String?
var location : String?
var topField : String?
let advertisement : String? //把这个常量改成变量,就好了
//指定构造器
init(name : String,location : String,topField : String,advertisement : String)
{
self.name = name
self.location = location
self.topField = topField
self.advertisement = advertisement
}
//便捷构造器
convenience init()
{
self.init(name : "蓝翔",location : "山东",topField : "挖掘机",advertisement : "挖掘机哪家强,中国山东找蓝翔")
}
//可失败构造器
init? (has3IDCard : Bool)
{
return nil ///会报告这个错误 All stored properties of a class instance must be initialized before returning nil from an initializer
}
//可失败构造器
convenience init! (isRumor : Bool)
{
self.init(name : "蓝翔",location : "山东",topField : "挖掘机",advertisement : "挖掘机哪家强,中国山东找蓝翔")
}
}
最近在学习swift,看的一本书上的例子,会报错,不知道是不是版本的原因,当类的属性有常量的时候,定义可失败构造器会报错 All stored properties of a class instance must be initialized before returning nil from an initializer
这样的话,如果类的属性需要这种特性,该怎么实现呢?哪位大神知道,求告知