不能获取活动指示器以显示在iPhone应用程序上 [英] Cant Get the activity indicator to show on iPhone app

问题描述

我有一个在IB中创建的视图.在其中，我有一个以编程方式创建的滚动视图.在滚动视图中，我连接到Web服务并获取内容和图像.我要在执行此操作时显示活动指示器.所以我有:

I have a view which is created in IB. inside it I have a scroll view created programmatically. Within the scroll view I connect to a web service and fetch the content and the image. I want to show an activity indicator while doing this. So I have:

- (void)viewDidLoad
{
    [super viewDidLoad];
    activityIndicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
    activityIndicator.frame = CGRectMake(0.0, 0.0, 40.0, 40.0);
    activityIndicator.center = self.view.center;
    [self.view.window addSubview:activityIndicator];

在添加scrollview之后，我有:

And right after the scrollview is added, I have:

[self.view addSubview:scrollView];
// ADD Scroll View Ends


    //Add the Lisitng Image
    NSOperationQueue *queue = [NSOperationQueue new];
    NSInvocationOperation *operation = [[NSInvocationOperation alloc] 
                                        initWithTarget:self
                                        selector:@selector(loadImage) 
                                        object:nil];
    [queue addOperation:operation]; 

在loadimage中，我有:

And in loadimage I have:

- (void)loadImage {

    [activityIndicator startAnimating];

我已经尝试过[self.view.window addSubview:activityIndi​​cator];，[self-> ScrollView addSubview:activityIndi​​cator]，[self.view addSubview:activityIndi​​cator];

I've tried [self.view.window addSubview:activityIndicator];, [self->ScrollView addSubview:activityIndicator];, [self.view addSubview:activityIndicator];

但是我无法显示该指示器.任何人都知道什么地方可能出问题了吗?

but I just can't get the indicator to show. Anyone have any idea what might be wrong?

推荐答案

您应该在viewDidload中做到这一点

You should do this in you viewDidload

- (void)viewDidLoad
{
    //Start Activity Indicator View
    indicatorView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    indicatorView.frame = CGRectMake(40.0, 20.0, 60.0, 60.0);
    indicatorView.center = self.view.center;
    [self.view addSubview:indicatorView];
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    [indicatorView startAnimating];

    [self performSelectorInBackground:@selector(loadscroll) withObject:self];
}

注意:"performSelectorInBackground"将在视图上显示活动指示器，并且您的loadScroll方法将从互联网上获取所有数据并进行其他工作.

Note: "performSelectorInBackground" will show you an activity indicator on the view and your loadScroll method will fetch all data from internet and do other work.

-(void)loadscroll
{
    //Your Scroll View 
        //Your other Data Manipulation even from internet
        //When data is fetched display it 
       [self removeActivityIndicator]; //To stop activity Indicator       
}

- (void)removeActivityIndicator
{
       [indicatorView stopAnimating];
}

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