iphone - 如何在 iOS 上的按钮操作上显示忙碌指示器？

Question

我想在按钮操作上启动繁忙指示器，我在 IB 操作中使用以下代码:

 busyIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
 busyIndicator.center = self.view.center;
 [busyIndicator setColor:[UIColor redColor]];
 [self.btnInjuryPrevention addSubview:busyIndicator];
 [self.view addSubview:busyIndicator]; // spinner is not visible until started

[busyIndicator startAnimating];
if(![AppStatus isAppOnline]) {
    noInternetViewController = [[NoInternetViewController alloc] initWithNibName:@"NoInternetViewController" bundle:[NSBundle mainBundle]];
    noInternetViewController.view.tag = CHILD_CONTROLLER_TAG;
    [self.navigationController pushViewController:noInternetViewController animated:YES];
    NSLog(@"Yoy are offline..>!!");
}
else
{
    mInjuryPreventionViewController=[[InjuryPreventionViewController alloc] initWithNibName:@"InjuryPreventionViewController" bundle:nil withHeader:@" Injury Prevention" withId:INJURY_PREVENTION_ID];
    mInjuryPreventionViewController.view.tag = CHILD_CONTROLLER_TAG;
    [self.navigationController pushViewController:mInjuryPreventionViewController animated:YES];
    //[mInjuryPreventionViewController release];
}
// [self removeLoadingView];
[busyIndicator stopAnimating];

我使用上面的代码，但是繁忙的指示器不会启动，所以你能告诉我这可能吗？

Answer 1

如果您在单个 block 中启动和停止动画，您将看不到任何内容。你可以想到startAnimating方法表示“当控制返回操作系统时开始动画”。

目前尚不清楚为什么你需要一个微调器。创建 View Controller 需要很长时间吗？不过，如果您将 View Controller 的内容移动到新方法中，您可以执行以下操作:

...
// create busy indicator
[busyIndicator startAnimating];
[self performSelector:@selector(createViewController) withObject:nil afterDelay:0]; 

...

// at the end of the createViewController method...
[busyIndicator stopAnimating];