ios単例モード

単一モード
このクラスは常に1つのオブジェクト(同じ)しか作成できません.
手順:

クラスYQConfig

を作成

クラスメソッド

を書く

 ```
+(instancetype)config{
static YQConfig*instance;
static dispatch_once_t onceToken;

dispatch_once(&onceToken, ^{
    instance=[[YQConfig alloc]init];
});

return instance;

}

```

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    
    YQConfig*config1=[[YQConfig alloc]init ];
    NSLog(@"config1 %@ ",config1);
    
    YQConfig*config2=[[YQConfig alloc]init];
    NSLog(@"config2 %@ ",config2);
        
    YQConfig *config3=[YQConfig config];
    NSLog(@"config3  %@",config3   );

    YQConfig*config4=[YQConfig config ];
    NSLog(@"config4  %@ ",config4   );   
}

     :
2016-07-19 11:34:20.996     [5486:2851930] config1  
2016-07-19 11:34:20.997     [5486:2851930] config2  
2016-07-19 11:34:20.997     [5486:2851930] config3  
2016-07-19 11:34:20.997     [5486:2851930] config4   
    :