IOS 如何从ViewController获取一个UIView上的某种或者某个控件

某种：遍历

  for (UIView *subView in self.view.subviews) {
        if ([subView isKindOfClass:[UIButton class]]) {
            NSLog(@"subview==%@",subView);
        }
    }

某个：给某个控件设置TAG，在IB中可以设置

UIActivityIndicatorView *uiv;
uiv = [self.view viewWithTag:UIV];
[uiv startAnimating];