Objective-C中的普通铸造与桥梁铸造 [英] Normal casting vs bridge casting in Objective - C

问题描述

两者有什么不同，

(CFDataRef) data

&

(__bridge CFDataRef) data

Xcode 要求我将其更改为桥接.是因为 ARC 吗?

Xcode asked me to change it to bridge. Is that because of ARC?

推荐答案

是的，当您在免费桥接类型之间进行转换时，需要给 ARC 提供说明.在这种情况下，__bridge 告诉 ARC 什么都不做，所以它的行为与之前的标准转换相同.

Yes, ARC needs to be given instructions when you cast between toll-free bridged types. In this case __bridge tells ARC to do nothing, so this will behave the same as the previous standard cast.

您可以阅读 过渡到 ARC 发行说明有关进行桥接演员表的不同方法的更多详细信息.

You can read the Transitioning to ARC Release Notes for more details on the different ways to do bridging casts.

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