简单的Loding

UIActivityIndicatorView *indicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
indicator.size = CGSizeMake(80, 80);
indicator.center = CGPointMake(self.view.width / 2, self.view.height / 2);
indicator.backgroundColor = [UIColor colorWithWhite:0.000 alpha:0.670];
indicator.clipsToBounds = YES;
indicator.layer.cornerRadius = 6;
[indicator startAnimating];
[self.view addSubview:indicator];