正确使用NS_DESIGNATED_INITIALIZER

最新推荐文章于 2019-11-07 11:42:15 发布

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最新推荐文章于 2019-11-07 11:42:15 发布 · 1.5w 阅读

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#iOS #Objective-C #OC

本文探讨了在Objective-C中遇到的"Method override for the designated initializer"警告，解释了NS_DESIGNATED_INITIALIZER的作用，即指定类的构造器。文章强调了正确使用NS_DESIGNATED_INITIALIZER的重要性，包括为何使用它、如何避免警告，以及如何通过NS_UNAVAILABLE宏来限制初始化方式，以确保代码的正确性和一致性。同时，建议避免使用new关键字创建对象，因为它可能不会触发编译器的警告。

为什么会提到NS_DESIGNATED_INITIALIZER

最近在清理项目警告，遇到了“Method override for the designated initializer”的警告，全称为：

Method override for the designated initializer of the superclass '-init' not found 或者
Method override for the designated initializer of the superclass '-initWithNibName:bundle:' not found。

经排查是因为头文件中出现NS_DESIGNATED_INITIALIZER 声明的初始化方法，如下：

 
          // .h 
         
          - (instancetype)initWithPurchaseService:(HTLPrepayPurchaseService *)service NS_DESIGNATED_INITIALIZER;

如果用了NS_DESIGNATED_INITIALIZER，那么警告中出现init还是initWithNibName或是其它，取决于你的继承的父类类型：

UIViewController

Method override for the designated initializer of the superclass '-initWithNibName:bundle:' not found
Method override for the designated initializer of the superclass '-initWithCoder:' not found

UIView

Method override for the designated initializer of the superclass '-initWithFrame:' not found
Method override for the designated initializer of the superclass '-initWithCoder:' not found

NSObject