ios单例模式-全局静态类

@interface GlobalSingleton : NSObject{
}
+(GlobalSingleton*)sharedGlobalSingleton;

@implementation GlobalSingleton
-(id)init{
    self = [super init];
    if(self){
        //全局属性初始化
    }
    return self;
}
+(GlobalSingleton*)sharedGlobalSingleton{
    static GlobalSingleton *sharedGlobalSingleton;
    @synchronized(self){
        if (!sharedGlobalSingleton)
            sharedGlobalSingleton = [[GlobalSingleton alloc] init];
        return sharedGlobalSingleton;
    }
}