Ios iphone下载指示灯未显示

我下载了某些数据，当它被下载时，这个方法被调用：

- (void)connectionDidFinishLoading:(NSURLConnection *)connection;

-(IBAction)update:(id)sender
{
///la la la updating
JManager *manager1=[[JManager alloc] initWithDate:dateString andCategory:@"projects"];
            manager1.delegate=self;
            [manager1 requestProjects];
}

在这种方法中，我应该在视图控制器中呈现一个旋转图像，这是我执行的委派操作，当下载数据时，我会删除此旋转图像：

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

[delegate showIndicator];

//Complex data downloading

[delegate hideIndicator];
}

因此，当connectionFinishedLoading发生时，会调用这些方法，但不会调用它们。以下是它们的实现：

-(void)showIndicator;
{
    NSLog(@"Show indicator");
    UIImage *statusImage = [UIImage imageNamed:@"update.png"];
    activityImageView = [[UIImageView alloc] initWithImage:statusImage];
    // Make a little bit of the superView show through

    activityImageView.animationImages = [NSArray arrayWithObjects:
                                         [UIImage imageNamed:@"update.png"],
                                         [UIImage imageNamed:@"update2.png"],
                                         [UIImage imageNamed:@"update3.png"],
                                         [UIImage imageNamed:@"update4.png"],
                                         nil];
    activityImageView.frame=CGRectMake(13, 292, 43, 44);
    activityImageView.animationDuration = 1.0f;
    [rightView addSubview:activityImageView];
    [activityImageView startAnimating];
}
-(void)hideIndicator
{  NSLog(@"Hide indicator");
     [activityImageView removeFromSuperview];
}

这就是我创建JManager对象的地方，为其调用connectionFinished事件：

- (void)connectionDidFinishLoading:(NSURLConnection *)connection;

-(IBAction)update:(id)sender
{
///la la la updating
JManager *manager1=[[JManager alloc] initWithDate:dateString andCategory:@"projects"];
            manager1.delegate=self;
            [manager1 requestProjects];
}

---

为什么我的自定义指示器添加不能代表Jmanager对象完成？谢谢

假设您从主线程调用NSURLConnection，该方法不会异步执行，因此在启动和停止该方法之间没有机会显示该指示器

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

    [delegate showIndicator];

    //Complex data downloading

    [delegate hideIndicator];
}

您应该在

-（void）connectionIDReceiveResponse

方法中调用

[delegate showIndicator]

，如下所示：

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    //connection starts
    [delegate showIndicator];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

    //connection ends
    [delegate hideIndicator];
}    

---

请参阅更新。基本上，在下载完成后，您都开始并停止了活动。实际上，您希望在下载开始时启动它，然后在下载完成时停止它；当您实际创建NSURLConnection而不是等待响应时，因为响应可能需要几秒钟，然后下载几乎立即发生。请将NSLog放入ConnectionIDFinishLoading方法中，并实现其他NSURLConnection方法，如connectionIDFailWitherRor，并将日志记录放在这些方法中。有时可能是您的请求失败或超时。当连接结束时，仍然没有调用hideIndicator