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// .h文件 #define HMSingletonH(name) + (instancetype)shared##name; // .m文件 #if __has_feature(objc_arc) #define HMSingletonM(name) static id _instace; + (id)allocWithZone:(struct _NSZone *)zone { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instace = [super allocWithZone:zone]; }); return _instace; } + (instancetype)shared##name { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instace = [[self alloc] init]; }); return _instace; } - (id)copyWithZone:(NSZone *)zone { return _instace; } #else #define HMSingletonM(name) static id _instace; + (id)allocWithZone:(struct _NSZone *)zone { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instace = [super allocWithZone:zone]; }); return _instace; } + (instancetype)shared##name { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instace = [[self alloc] init]; }); return _instace; } - (id)copyWithZone:(NSZone *)zone { return _instace; } - (oneway void)release { } - (id)retain { return self; } - (NSUInteger)retainCount { return 1;} - (id)autorelease { return self;} #endif
//系统自带判断条件语句
#if _has_feature(bbjc_arc)
//如果是arc模式，实现这里面的代码
#else
//如果是Mvc模式，实现这里面的代码
#endif
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原文地址：http://www.cnblogs.com/lizhan1991/p/4710334.html
