Objective C property attributes

I have a background in .NET, but am new to iOS development (objective C).

What is the meaning of the strong vs. weak attributes of properties as in:

@property(strong) NSString *make;
@property(weak) NSString *make;
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pzozulkaAsked:
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darbid73Commented:
I also do a little in .Net and do not think there is an equivalent.

In most cases I think people use a strong reference. This means that you want to "own" the object you are referencing with this property/variable. When compiled (assuming you are using ARC) any object that you assign to this property should not be destroyed providing you or some other object points to it with a strong reference. The object gets destroyed once it is set to nil (unless one or more other objects also hold a strong reference to it).

For a weak reference you signify that you don't want to have control over the object's lifetime. This kind of object only stays alive because at least one other object holds a strong reference to it. Once that is no longer the case, the object gets destroyed and your weak property will automatically get set to nil. The most frequent use cases of weak references in iOS are for delegates (to avoid retain cycles) and subviews because these have a main view controller that should hold a reference to the subview strongly.
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