Question

我正在使用此观察者：UIDeviceOrientationDidChangeNotification来检测用户何时更改设备方向。当方向更改为横向时，我会将其更改为纵向时显示新的UIViewController或关闭此UIViewController。

当用户开始快速旋转设备的次数并快速启动我的问题时，应用程序会发疯，直到我收到此错误：

警告：尝试显示其视图不在窗口层次结构中！`。

等待动画结束然后更改旋转的最佳方法是什么？

这就是我在呈现视图控制器：

上使用的内容

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self beginDeviceOrientationListener];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)beginDeviceOrientationListener
{
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:UIDeviceOrientationDidChangeNotification object:[UIDevice currentDevice]];
}

- (void)orientationChanged:(NSNotification *)notification
{
    UIDevice *device = notification.object;
    switch (device.orientation)
    {
        case UIDeviceOrientationLandscapeLeft:
        case UIDeviceOrientationLandscapeRight:
        {
            TheViewControllerToPresent *viewController = [[TheViewControllerToPresent alloc] init];
            [self presentViewController:viewController animated:YES completion:nil];
            [[UIDevice currentDevice] setValue:[NSNumber numberWithInteger:UIInterfaceOrientationLandscapeRight] forKey:@"orientation"];
            [[UIApplication sharedApplication] setStatusBarOrientation:[[[UIDevice currentDevice] valueForKey:@"orientation"] integerValue] animated:YES];
            [[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationSlide];
        }
            break;

        default:
            break;
    }
}

这就是我在呈现的视图控制器上使用的内容：

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self beginDeviceOrientationListener];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)beginDeviceOrientationListener
{
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:UIDeviceOrientationDidChangeNotification object:[UIDevice currentDevice]];
}

- (void)orientationChanged:(NSNotification *)notification
{
    UIDevice *device = notification.object;
    switch (device.orientation)
    {
        case UIDeviceOrientationPortrait:
        {
            [self dismissViewControllerAnimated:YES completion:nil];
            [[UIDevice currentDevice] setValue:[NSNumber numberWithInteger:UIInterfaceOrientationPortrait] forKey:@"orientation"];
            [[UIApplication sharedApplication] setStatusBarOrientation:[[[UIDevice currentDevice] valueForKey:@"orientation"] integerValue] animated:YES];
        }
            break;
        default:
            break;
    }
}

Answer 1

我自己使用的最简单的解决方案是阻止用户在动画进行过程中进行任何更改。

这是通过在动画开始时添加以下代码来完成的：

[[UIApplication sharedApplication] beginIgnoringInteractionEvents];
[[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];

和完成处理程序：

[[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
[[UIApplication sharedApplication] endIgnoringInteractionEvents];

用户可以旋转设备但是在动画期间不会生成事件，因此动画不会发生碰撞。但是，当动画结束时，您应该明确检查方向：

UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];

看你是否应该开始另一部动画。

UIViewController动画等到动画完成

1 个答案: