Objective-C综合属性名称覆盖 [英] Objective-C synthesize property name overriding

问题描述

我试图通过属性名称覆盖来理解synthesize指令的目的.假设我有一个定义如下的接口:

I am trying to understand the purpose of the synthesize directive with property name overriding. Say that I have an interface defined as follow:

@interface Dummy ... {
    UILabel *_dummyLabel;
}

@property (retain, nonatomic) UILabel *dummyLabel;

在实现文件中，我有:

@synthesize dummyLabel = _dummyLabel;

据我了解，"dummyLabel"只是实例变量"_dummyLabel"的别名. self._dummyLabel和self.dummyLabel之间有什么区别吗?

From what i understand, "dummyLabel" is just an alias of the instance variable "_dummyLabel". Is there any difference between self._dummyLabel and self.dummyLabel?

推荐答案

是. self._dummyLabel未定义，但是_dummyLabel未定义.

Yes. self._dummyLabel is undefined, however _dummyLabel is not.

点语法扩展为简单的方法调用，因此它不是特定于属性的.如果您有一个名为-(id)someObject的方法，例如在object.someObject的情况下，就好像您编写了[object someObject];.

Dot syntax expands out to simple method invocations, so it's not specific to properties. If you have a method called -(id)someObject, for example in the case of object.someObject, it will be as if you wrote [object someObject];.

self.dummyLabel  //works
self._dummyLabel //does not work
dummyLabel       //does not work
_dummyLabel      //works
[self dummyLabel];  //works
[self _dummyLabel]; //does not work

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