iOS 7+ 关闭模态视图 Controller 并强制纵向

Question

我有一个 UINavigationController 作为我在 iOS 7 和 iOS 8 上的 UIWindow 的 Root View Controller 。从它的一个 View Controller ，我展示了一个具有交叉溶解呈现样式的全屏模态视图 Controller 。这个模态视图 Controller 应该能够旋转到所有方向，并且工作正常。

问题是当设备以横向放置并且模态视图 Controller 被关闭时。呈现模态的 View Controller 仅支持纵向，并且我已确认 UIInterfaceOrientationMaskPortrait 已返回到 -application:supportedInterfaceOrientationsForWindow:。 -shouldAutorotate 也返回 YES。但是，呈现 View Controller 的方向在关闭模式后仍保持横向。如何在允许模式采用设备方向的同时强制它保持纵向？我的代码如下:

应用委托(delegate):

- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
{
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
        UINavigationController *navigationController = (UINavigationController *)self.deckController.centerController;
        NSArray *viewControllers = [navigationController viewControllers];
        UIViewController *top = [viewControllers lastObject];

        if (top && [top presentedViewController]) {
            UIViewController *presented = [top presentedViewController];
            if ([presented respondsToSelector:@selector(isDismissing)] && ![(id)presented isDismissing]) {
                top = presented;
            }
        }

        return [top supportedInterfaceOrientations];
    }

    return (UIInterfaceOrientationMaskLandscapeLeft|UIInterfaceOrientationMaskLandscapeRight);
}

呈现 View Controller :

- (BOOL)shouldAutorotate {
    return YES;
}

- (NSUInteger)supportedInterfaceOrientations {
    return UIInterfaceOrientationMaskPortrait;
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    return UIInterfaceOrientationPortrait;
}

模态视图 Controller :

- (BOOL)shouldAutorotate
{
    return YES;
}

- (NSUInteger)supportedInterfaceOrientations
{
    return (UIInterfaceOrientationMaskLandscape|UIInterfaceOrientationMaskLandscapeLeft|UIInterfaceOrientationMaskPortrait);
}

Answer 1

如果模态 Controller 在关闭前处于横向，则呈现的 ViewController 可能不会返回到原始方向(纵向)。问题是因为 AppDelegate supportedInterfaceOrientationsForWindow 方法在 Controller 实际关闭之前被调用，并且呈现的 Controller 检查仍然返回 Landscape mask。

设置一个标志以指示是否显示(模态)presented View Controller 。

- (void)awakeFromNib // or where you instantiate your ViewController from
{
    [super awakeFromNib];
    self.presented = YES;
}

- (IBAction)exitAction:(id)sender // where you dismiss the modal
{
    self.presented = NO;
    [self dismissViewControllerAnimated:NO completion:nil];
}

并且在模态呈现的 ViewController 中根据标志设置方向:当模态 ViewController 呈现时 - 返回 Landscape。当它被解雇时，然后返回肖像

- (NSUInteger)supportedInterfaceOrientations
{
    if ([self isPresented]) {
        return UIInterfaceOrientationMaskLandscape;
    } else {
        return UIInterfaceOrientationMaskPortrait;
    }
}

最后一步 - 从您的 AppDelegate 调用模态呈现的 ViewController 的方向。我只是检查当前呈现的 ViewController 并在其上调用 supportedInterfaceOrientations

- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
{
    NSUInteger orientationMask = UIInterfaceOrientationMaskPortrait;

    UIViewController *currentVC = self.window.rootViewController.presentedViewController; // gets the presented VC
    orientationMask = [currentVC supportedInterfaceOrientations];

    return orientationMask;
}

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