委托属性声明中'weak'和'assign'之间的区别是什么

Question

Whats the difference between this:

@property (nonatomic, weak) id  <SubClassDelegate> delegate; 

and this:

@property (nonatomic, assign) id  <SubClassDelegate> delegate; 

I want to use property for delegates.

Answer 1

The only difference between weak and assign is that if the object a weak property points to is deallocated, then the value of the weak pointer will be set to nil , so that you never run the risk of accessing garbage. If you use assign , that won't happen, so if the object gets deallocated from under you and you try to access it, you will access garbage.

For Objective-C objects, if you're in an environment where you can use weak , then you should use it.