我需要手动释放 CFStringRef 吗?

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问题描述

你能告诉我哪种方法是正确的，为什么在非 ARC 世界中.

Can you please tell me which is the right way and why in non ARC world.

+ (NSString *)getUUID {
CFUUIDRef theUUID = CFUUIDCreate(NULL);
CFStringRef string = CFUUIDCreateString(NULL, theUUID);
CFRelease(theUUID);
return [(NSString*) string autorelease];
}

或

+ (NSString *)getUUID {
CFUUIDRef theUUID = CFUUIDCreate(NULL);
CFStringRef string = CFUUIDCreateString(NULL, theUUID);
CFRelease(theUUID);
return (NSString*)string;
}

推荐答案

其他答案对于手动保留计数是正确的.当你清醒过来 ;^) 并切换到 ARC 时，你将无法发送 autorelease.相反，在 ARC 下，这样做:

The other answers are correct for manual retain counting. When you come to your senses ;^) and switch to ARC, you won't be able to send autorelease. Instead, under ARC, do it this way:

+ (NSString *)getUUID {
    CFUUIDRef theUUID = CFUUIDCreate(NULL);
    CFStringRef string = CFUUIDCreateString(NULL, theUUID);
    CFRelease(theUUID);
    return CFBridgingRelease(string);
}

CFBRidgingRelease 等价于 CFRelease，用于平衡 CFUUIDCreateString 返回的 +1 保留计数，但也返回一个静止的-ARC 将负责发布的有效引用.

A CFBridgingRelease is equivalent to a CFRelease for the purposes of balancing the +1 retain count returned by CFUUIDCreateString, but also returns a still-valid reference that ARC will take care of releasing.

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