IOS，ARC，属性:(readwrite，nonatomic)vs(radwrite，retain，nonatomic) [英] IOS, ARC, Property: (readwrite, nonatomic) vs (radwrite, retain, nonatomic)

问题描述

我已经阅读了一些关于 ARC 的教程，但对属性声明仍然有些困惑.我使用以下模式编写了大部分代码:

I am have read up some tutorials on ARC and am still left a bit confused on properties declarations. I wrote most most my code using the following pattern:

@property (readwrite, nonatomic) PlayerData* playerData;
@property (readwrite, nonatomic) MusicLayer* musicLayer;
@property (readwrite, nonatomic) bool isPowerUpAvailable;

现在我终于开始处理内存泄漏了，XCode 建议我在一些代码中应该在属性声明中添加retain"关键字.

Now that I finally started to deal with memory leaks XCode suggested me that in some bits of code I should have added the "retain" keyword in the property declaration.

使用 ARC，我认为我不应该再打扰"保留计数了.是否有一些我没有得到或缺少的概念?任何教程参考或解释将不胜感激.

Using ARC I thought I shouldn't "Bother" about retain counts anymore. Is there some concept I am not getting or missing? Any tutorial references or explanation would be greatly appreciated.

推荐答案

ARC会根据属性声明来保留对象，需要保留的属性使用strong，对于不需要保留的属性weak.

ARC is will retain object based on the property declaration, you should use strong for properties that need to be retained and weak for properties that do not need to be retained.

weak 属性在对象被释放时也会被清零.

weak properties are also nilled when the object is deallocated.

编译器将始终假定属性为 readwrite，因此无需以这种方式声明.

The compiler will always assume that properties are readwrite so there is no need to declare then this way.

@property (strong, nonatomic) PlayerData* playerData;
@property (strong, nonatomic) MusicLayer* musicLayer;
// Need use assign since strong is for objects only.
@property (assign, nonatomic) bool isPowerUpAvailable;

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