如何在导航栏中添加活动指示器？

Question

我在我的应用中使用活动指示器视图.

当我点击一个按钮时,我希望活动指示器在导航栏中显示10秒然后自动隐藏.

我在视图中使用以下代码加载:

CGRect frame = CGRectMake(0.0, 0.0, 25.0, 25.0);

self.activity = [[UIActivityIndicatorView alloc]
             initWithFrame:frame];

[self.activity sizeToFit];

self.activity.autoresizingMask =
    (UIViewAutoresizingFlexibleLeftMargin |
     UIViewAutoresizingFlexibleRightMargin |
     UIViewAutoresizingFlexibleTopMargin |
     UIViewAutoresizingFlexibleBottomMargin);

UIBarButtonItem *loadingView = [[UIBarButtonItem alloc] initWithCustomView:self.activity];
loadingView.target = self;
self.navigationItem.rightBarButtonItem = loadingView;   

在按钮操作中,我只启动指示器:

[self.activity startanimating];

但我在导航栏中看不到指示器.

如果我的代码中有任何问题,请告诉我...

Answer 1

UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
UIBarButtonItem *itemIndicator = [[UIBarButtonItem alloc] initWithCustomView:activityIndicator];
[self.navigationItem setLeftBarButtonItem:itemIndicator];
[activityIndicator startAnimating];