单例的创建

单例是一种特殊的对象,这个类唯一的对象,单例的几种创建方式

+ (Singleton *)shareSingleton {static Singleton *single = nil;

保证线程只走一次

static dispatch_once_t oneToken;

dispatch_once(&oneToken,^{

single = [Singleton alloc]init];

});

return single;}

+ (Singleton *)shareSingleton {static Singleton *single;if (single  == nil) {   single = [Singleton alloc]init];}

 return single;

}

 

转载于:https://www.cnblogs.com/forever54780/p/4859460.html