如何创建完整版单例

1.声明单例对象

在.h文件

+(SingleCase *)sharedSingleCase;

     

2.实现单例

在.m文件

SingleCase *  singleCase = nil; 

 

+(SingleCase *)sharedSingleCase{

 

     static dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{
        //        第一次
        //        singleCase = [[SingleCase alloc]init];
        //        singleCase = [SingleCase allocWithZone:NULL]init];
        //        singleCase = [[self alloc]init];
        //        singleCase =  [self allocWithZone:NULL]init];
        singleCase = [[super allocWithZone:NULL]init];
    });
    return singleCase;

}

 

//=================遵守 <NSCopying,NSMutableCopying>

 

-(id)copyWithZone:(NSZone *)zone{
    return self;
}

-(id)mutableCopyWithZone:(NSZone *)zone{
    return self;
}

+(instancetype)allocWithZone:(struct _NSZone *)zone{
    return [SingleCase sharedSingleCase];
}
//防止copy
+ (id)copyWithZone:(NSZone *)zone{
    return [SingleCase sharedSingleCase];
   
}
//防止mutable
+(id)mutableCopyWithZone:(struct _NSZone *)zone
{
    return [SingleCase sharedSingleCase];
}
-(oneway void)release
{
 
}
-(instancetype)autorelease{
    return self;
}
-(instancetype)retain{
    return self;
}
-(NSUInteger)retainCount{
    return NSIntegerMax;

}