When to use __bridge_transfer and __bridge [duplic

问题:

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Where and how to __bridge (2 answers)

Closed 7 years ago.

1. Can any one explain me what is '__bridge_transfer' and '_bridge' & when to use '_bridge_transfer' and '__bridge'
2. I read something like its deals with ARC, So what is the main function of these both

Thanks,

回答1:

These keywords are used to tell to ARC system how to handle your non-objective-c pointers. In essence, if you use __bridge, you are telling to ARC not to deal with the ownership of the converted pointer because you will free it from non-objective-c code, most likely with a free() or a CFRelease... type function. __bridge_transfer, on the other hand, transfers the ownership to ARC and ARC will free your objective-c (and thus also the original non-objective-c) object via the standard release mechanism when the references to that object hits zero.