@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;    }}