NSString在Objective-C中保留计数 [英] NSString retain count in Objective-C

问题描述

NSString* nsString=[[NSString alloc]initWithString:@"nsString"];
NSLog(@"nsString RetainCount:%li",[nsString retainCount]);

相应的结果是:

 2013-03-04 11:18:03.291 ARC[655:303] nsString RetainCount:-1 

另外: 如果使用init NSMutableString实例； 它返回1；

in addition: if use init a NSMutableString instance; it return 1;

推荐答案

http://whentouseretaincount.com

在编译时生成的不可变NSStrings是单例.因此，他们根本不做retain/release舞蹈.

Immutable NSStrings generated at compile time are singletons. Thus, they don't do the retain/release dance at all.

NSString检测何时使用此类初始化，并直接直接返回字符串.您会发现该代码中alloc返回的对象与init...调用返回的对象不同.

NSString detects when it is initialized with such and just returns the string directly. You'd find that the object returned by alloc in that code is different than the one returned by the init... call.

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