What is the main difference using “copy” and “strong” ownership qualifiers in property declaration with block types?

问题

Example #1

@property (nonatomic, copy) void (^errorBlock) (NSError *);

Example #2

@property (nonatomic, strong) void (^errorBlock) (NSError *);

I know that blocks are standard variables on stack, and by making a copy we are "moving" them to the heap.

Thats all? Or not?

回答1:

There should be no difference. Since the property has a block type, according to http://clang.llvm.org/docs/AutomaticReferenceCounting.html#blocks

With the exception of retains done as part of initializing a __strong parameter variable or reading a __weak variable, whenever these semantics call for retaining a value of block-pointer type, it has the effect of a Block_copy.

来源：https://stackoverflow.com/questions/16426382/what-is-the-main-difference-using-copy-and-strong-ownership-qualifiers-in-pr