Question

我想在单击UIButton时添加一个activityindicator并继续设置动画，直到来自服务url的数据加载为止。如果它加载则会移动到下一个视图。但是我无法这样做..

这是我的代码..

 -(IBAction)switchtoGetProviders
    {
        UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc]initWithFrame:CGRectMake(225, 115, 30, 30)];
        [activity setBackgroundColor:[UIColor clearColor]];
        [activity setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
        [self.view addSubview:activity];
        [activity release];
        [activity startAnimating];

        NSURL *urlString= [NSString stringWithFormat:@"http://www.something.net/service.svc/Xml"];

        if(arr.count>0)
        {
            [activity stopAnimating];
            ViewController2 *gp=[ViewController2 alloc];
            [self presentModalViewController:gp animated:NO];
            [gp release];
        }
else
{
 UIAlertView *alert = [[[UIAlertView alloc]initWithTitle: @"Results not found"
                                                                  message: @""
                                                                 delegate: self
                                                        cancelButtonTitle:@"OK"
                                                        otherButtonTitles:nil]autorelease];


                  [alert show];         
       }
    }

实际上，当arr为null时，我会得到一个alertView。当alertView出现时activityindicator正在启动。当我点击alertView的确定按钮时，它会停止制作动画。但是我希望它在触摸UIbutton时立即启动。我该怎么做？哪里出错？

Answer 1

在停止制作动画之前不要释放它...如果你发布那么你就失去了对它的引用..

 [activity release];//Dont Release here 
 [activity startAnimating]; 



     [activity stopAnimating];
[activity release];

Answer 2

您的代码存在多个问题。

首先是发布，这是早期，第二，你没有给UI任何时候添加UIActivityIndicatorView并让它开始动画。您也忘记了init您分配的ViewController2。

我还猜你没有发布所有代码，因为NSURL *urlString= [NSString stringWithFormat:@"http://....不会创建有效的NSURL对象。我也很想知道你来自arr的{{1}}变量。

如果您真的想在一种方法中完成所有操作，则必须使用GCD。

-(IBAction)switchtoGetProviders
{
    UIActivityIndicatorView *activity = [[UIActivityIndicatorView alloc]initWithFrame:CGRectMake(225, 115, 30, 30)];
    [activity setBackgroundColor:[UIColor clearColor]];
    [activity setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
    [self.view addSubview:activity];
    [activity startAnimating];

    int64_t delayInSeconds = 0.1;
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

        NSURL *urlString= [NSString stringWithFormat:@"http://www.something.net/service.svc/Xml"];

        if(arr.count>0) {
            [activity stopAnimating];
            [activity  removeFromSuperview];
            [activity release];
            ViewController2 *gp= [[ViewController2 alloc] init];
            [self presentModalViewController:gp animated:NO];
            [gp release];
        } else { 
            UIAlertView *alert = [[[UIAlertView alloc]initWithTitle: @"Results not found" message: @"" delegate: self cancelButtonTitle:@"OK" otherButtonTitles:nil]autorelease];
            [alert show];
            [alert release];
    });
}

activityindicator没有在iPhone上进行UIButton点击工作？

2 个答案: