我需要手动释放CFStringRef吗？

Question

你能告诉我哪种方式正确,为什么在非ARC世界.

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

要么

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

Answer 1

CFStrings确实需要发布.第一种方法是正确的,因为CFString是使用NSString 免费桥接的,因此可以像NSString一样安全地自动释放.

Answer 2

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

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

A CFBridgingRelease等效于a,CFRelease用于平衡返回的+1保留计数CFUUIDCreateString,但也返回ARC将负责释放的仍然有效的引用.