带有提示和活动指示器的 UINavigationItem

Question

我想知道 Apple 是如何在标题上方实现包含活动指示器（见下图）的 UINavigationItem。这是允许这样做的Apple私有API吗？如果没有，如何在应用程序中重现。

UINavigationItem with prompt and activity indicator http://img218.imageshack.us/img218/8819/img0133g.png

谢谢！

Answer 1

我用这段代码得到了与你的截图完全相同的渲染：

 UIView                      *viewContainingSpinner;
    UIActivityIndicatorView     *activityIndicatorView;
    UIBarButtonItem             *activityButtonItem;
    UIBarButtonItem             *rightBarButtonItem;


    // Configuring the title and the prompt title of the navigation bar
    [self.navigationItem setTitle:@"MobileMe"];
    [self.navigationItem setPrompt:@"Vérification du compte MobileMe"];

    // We will create a UIBarButtonItem that has a custom view (viewContainingSpinner).
    // A subview of viewContainingSpinner will be a UIActivityIndicatorView (activityIndicatorView)
    // We need to have this "intermediate" view to position the spinner at the right position (the UIBarButtonItem ignores the origin and height of its custom view)
    viewContainingSpinner = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 60, 85)];
    activityIndicatorView = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(20, 0, 20, 20)];
    [viewContainingSpinner addSubview:activityIndicatorView];
    [activityIndicatorView startAnimating];
    [activityIndicatorView release];

    activityButtonItem = [[UIBarButtonItem alloc] initWithCustomView:viewContainingSpinner];
    self.navigationItem.leftBarButtonItem = activityButtonItem;
    [viewContainingSpinner release];
    [activityButtonItem release];

    // Finally, configuring the right button
    rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Enregistrer" style:UIBarButtonItemStylePlain target:nil action:nil];
    [rightBarButtonItem setEnabled:NO];
    self.navigationItem.rightBarButtonItem = rightBarButtonItem;
    [rightBarButtonItem release];

PS：在实际应用程序中，我建议不要在代码中使用本地化字符串。 “验证”一词的 é 可能会给您带来麻烦。 看看方法NSLocalizedString。