在iPhone上的UITabBar应用程序中的活动指示器 [英] Activity indicator in a UITabBar application on the iPhone

问题描述

我有一个UITabBar + UINavigationController应用程序，它通常需要来自互联网的数据。有时它需要一段时间才会得到它，所以我想显示一个活动指示器。

I have a UITabBar + UINavigationController application which often needs data from the internet. Sometimes it takes quite a while before it gets it, so I would like to show an activity indicator.

我想要的是在我的窗口中添加一个activityView applicationDidFinishLaunching方法：

What I was trying is to add a activityView to my window in my applicationDidFinishLaunching method:

[window addSubview:tabBarController.view];
fullscreenLoadingView.hidden = YES;
[window addSubview:fullscreenLoadingView];

然后我将应用程序委托作为观察者添加到默认通知中心：

And then I add the application delegate as a observer to the default notification center:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(startFullscreenLoading:) name:@"startFullscreenLoading" object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(stopFullscreenLoading:) name:@"stopFullscreenLoading" object:nil];

并实施方法：

- (void)startFullscreenLoading:(NSNotification *)notification {
    fullscreenLoadingView.hidden = NO;
}

- (void)stopFullscreenLoading:(NSNotification *)notification {
    fullscreenLoadingView.hidden = YES;
}

当我在applicationDidFinishLaunching方法中直接使用它时，加载指示器视图显示upp

When I then use this directly in the applicationDidFinishLaunching method the loading indicator view shows upp as expected:

[[NSNotificationCenter defaultCenter] postNotificationName:@"startFullscreenLoading" object:self];

但是当我从一个导航控制器使用它时，startFullscreenLoading：方法被调用，见装载指示器视图。为什么？

But when I use it from one of the navigation controllers the startFullscreenLoading: method is called but I don't see the loading indicator view. Why is that?

推荐答案

您是在后台线程上加载数据吗？你的主线程将被阻塞&将无法重绘或处理任何其他事件。

Are you loading your data on a background thread? Your main thread will be blocked & won't be able to redraw or process any other events.

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