如何将CFStringRef转换为NSString？ [英] How to convert CFStringRef to NSString?

问题描述

NSString *aNSString;
CFStringRef aCFString;
aCFString = CFStringCreateWithCString(NULL, [aNSString UTF8String], NSUTF8StringEncoding);
aCFString = CFXMLCreateStringByUnescapingEntities(NULL, aCFString, NULL);

如何获得新的 NSString aCFString ？

推荐答案

NSString和CFStringRef都是免费桥接

NSString and CFStringRef are "Toll free bridged", meaning that you can simply typecast between them.

例如：

CFStringRef aCFString = (CFStringRef)aNSString;

工作完美透明。同样：

NSString *aNSString = (NSString *)aCFString;

上面的语法是用于MRC的。如果你使用ARC，新的转换语法如下：

The previous syntax was for MRC. If you're using ARC, the new casting syntax is as follows:

NSString *aNSString = (__bridge NSString *)aCFString;

也可以。需要注意的一点是，CoreFoundation通常会返回带有+1引用计数的对象，这意味着它们需要被释放（所有CF [类型]创建格式化函数都会这样做）。

works as well. The key thing to note is that CoreFoundation will often return objects with +1 reference counts, meaning that they need to be released (all CF[Type]Create format functions do this).

很好的是，在Cocoa中，你可以安全地使用autorelease或release来释放它们。

The nice thing is that in Cocoa you can safely use autorelease or release to free them up.

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