objective-c中的Singleton单例模式的完整实现示例

Objective中单例模式的实现，应该是比较完整的包括了objc的单例的各个点。详细看代码注释，注意最后用c++的析构函数实现instance的释放，所以源文件类型必须是.mm格式。

Singleton.h

// //Singleton.h //singleton // //Created by leondun on 11-4-20. //Copyright 2011 leondun. All rights reserved. // #import<Foundation/Foundation.h> @interfaceSingleton : NSObject { } +(Singleton*)getInstance; @end

Singleton.mm

#import"Singleton.h" staticSingleton* instance =nil; @interfaceSingleton(privateMethods) -(void)realRelease; @end @implementationSingleton //获取单例 +(Singleton*)getInstance { @synchronized(self) { if(instance ==nil) { [[selfalloc]init]; } } returninstance; } //唯一一次alloc单例，之后均返回nil + (id)allocWithZone:(NSZone*)zone { @synchronized(self) { if(instance ==nil) { instance = [superallocWithZone:zone]; returninstance; } } returnnil; } //copy返回单例本身 - (id)copyWithZone:(NSZone*)zone { returnself; } //retain返回单例本身 - (id)retain { returnself; } //引用计数总是为1 - (unsigned)retainCount { return1; } //release不做任何处理 - (void)release { } //autorelease返回单例本身 - (id)autorelease { returnself; } //真release私有接口 -(void)realRelease { [superrelease]; } // -(void)dealloc { //⋯⋯ printf("举例:在此处做一些单例结束时的收尾处理/n"); [superdealloc]; } @end //程序结束时析构静态c++类对象garbo， //在Garbo类的析构函数中释放instance structGarbo { ~Garbo(){[instance realRelease];} }; staticGarbo garbo;