iOS實現代碼只讓執行一次

- (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
 
  [self performSelector:@selector(wangmumu:) withObject:@"100" afterDelay:1];
}
 
- (void) wangmumu:(NSString *)han{
  static dispatch_once_t hanwanjie;
//只執行一次
  dispatch_once(&hanwanjie, ^{
    NSLog(@"12345678910");
  });
   
  int niha = [han intValue] - 1;
  if (niha == 10) {
    return;
  }
  [self performSelector:@selector(hanwanjie:) withObject:[NSString stringWithFormat:@"%d",niha] afterDelay:1];
}