Ios 尝试在视图不在窗口层次结构中的UIViewController上显示UIViewController
刚开始使用Xcode 4.5，我在控制台中遇到以下错误： 警告：尝试在其视图不在窗口层次结构中的Ios 尝试在视图不在窗口层次结构中的UIViewController上显示UIViewController,ios,cocoa-touch,ios6,views,hierarchy,Ios,Cocoa Touch,Ios6,Views,Hierarchy,刚开始使用Xcode 4.5，我在控制台中遇到以下错误： 警告：尝试在其视图不在窗口层次结构中的上显示 视图仍在显示中，应用程序中的所有内容都工作正常。这是iOS 6中的新功能吗 这是我用来在视图之间更改的代码： UIStoryboard *storyboard = self.storyboard; finishViewController *finished = [storyboard instantiateViewControllerWithIdentifier:@"finishViewC
UIStoryboard *storyboard = self.storyboard;
finishViewController *finished =
[storyboard instantiateViewControllerWithIdentifier:@"finishViewController"];
[self presentViewController:finished animated:NO completion:NULL];
您从何处调用此方法？我遇到了一个问题，我试图在
viewDidLoadviewdide:viewdiloadviewdilead:小心 如果在
viewdide:presentViewController:animated:completion:也许这不是展示模态视图控制器的最佳场所，或者可能需要保留一些附加状态，以允许显示视图控制器决定是否立即显示模式视图控制器。我在
viewDidLoadUIViewControlleraddChildViewController- (void)viewDidLoad
{
...
[self.view addSubview: navigationViewController.view];
[self addChildViewController: navigationViewController];
...
}
viewWillLayoutSubviewsviewdillayoutsubviewsviewControlleroverride func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let storyboard = UIStoryboard(name: "Main", bundle: nil)
if self.shouldSegueToMainTabBar {
let mainTabBarController = storyboard.instantiateViewController(withIdentifier: "mainTabBarVC") as! MainTabBarController
self.present(mainTabBarController, animated: true)
self.shouldSegueToMainTabBar = false
}
if self.shouldSegueToLogin {
let loginController = storyboard.instantiateViewController(withIdentifier: "loginVC") as! LogInViewController
self.present(loginController, animated: true)
self.shouldSegueToLogin = false
}
}
非UIViewControllerViewController[self presentViewController:]
[[[[UIApplication sharedApplication] delegate] window] rootViewController]
[self presentViewController:]
[[[[UIApplication sharedApplication] delegate] window] rootViewController]
由于某种原因（逻辑错误），
rootViewControllerUIViewControllerrootViewControllerUINavigationController所以，是的，这不是“神奇地找到正确的方法”，而是理解代码的位置和作用。我很高兴苹果公司给出了这样一个简单的英语警告信息，甚至带着感情。感谢做了这件事的苹果开发人员 我也有同样的问题。我必须嵌入一个导航控制器，并通过它呈现控制器。下面是示例代码
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
UIImagePickerController *cameraView = [[UIImagePickerController alloc]init];
[cameraView setSourceType:UIImagePickerControllerSourceTypeCamera];
[cameraView setShowsCameraControls:NO];
UIView *cameraOverlay = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 768, 1024)];
UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"someImage"]];
[imageView setFrame:CGRectMake(0, 0, 768, 1024)];
[cameraOverlay addSubview:imageView];
[cameraView setCameraOverlayView:imageView];
[self.navigationController presentViewController:cameraView animated:NO completion:nil];
// [self presentViewController:cameraView animated:NO completion:nil]; //this will cause view is not in the window hierarchy error
}
另一个潜在原因： 当我不小心两次演示同一个视图控制器时，我遇到了这个问题。（一次使用
performsguewithidentifer:sender:实际上，两个分段同时触发，我得到了一个错误：
尝试在Y上显示X，其视图不在窗口层次结构中如果播放视频时有AVPlayer对象，则必须先暂停视频。TL；DR您只能有一个rootViewController，它是最近出现的一个。因此，不要试图让一个viewcontroller呈现另一个viewcontroller，因为它已经呈现了一个未被忽略的viewcontroller
在做了一些我自己的测试之后，我得出了一个结论
如果您有一个rootViewController，希望显示所有内容，那么您可能会遇到此问题
这是我的根控制器代码（open是我从根显示viewcontroller的快捷方式）
如果我连续调用open两次（不管经过了多长时间），那么在第一次打开时就可以了，但在第二次打开时就不行了。第二次打开尝试将导致上述错误
但是，如果关闭最近显示的视图，然后调用“打开”，则在再次调用“打开”（在另一个viewcontroller上）时，它可以正常工作
我得出的结论是，只有最近调用的rootViewController位于视图层次结构上（即使您没有关闭它或删除视图）。我试着处理所有的加载程序调用（viewDidLoad、viewDidAppear和执行延迟调度调用），我发现让它工作的唯一方法是只从最顶层的视图控制器调用present 我也有同样的问题。问题是，performsguewithidentifier是由一个通知触发的，当我将通知放在主线程上时，警告消息就消失了 从内嵌在容器中的视图控制器执行segue时，也会收到此警告。正确的解决方案是从容器的父级使用segue，而不是从容器的视图控制器使用segue。必须写在第行下面
func close(controller:UIViewController)
{
ROOT_VIEW_CONTROLLER.dismissViewControllerAnimated(true, completion: nil)
}
self.searchController.definesPresentationContext = true
而不是
self.definesPresentationContext = true
在UIViewController中，考虑到您想在几乎任何地方显示一些viewController，我最终得到了这样一个代码，它最终对我有效（Swift）。当没有rootViewController a时，此代码显然会崩溃
UIViewController *yourCurrentViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (yourCurrentViewController.presentedViewController)
{
yourCurrentViewController = yourCurrentViewController.presentedViewController;
}
[yourCurrentViewController dismissViewControllerAnimated:YES completion:nil];
UIViewController *top = [UIApplication sharedApplication].keyWindow.rootViewController;
[top presentViewController:secondView animated:YES completion: nil];
/// independant window for alerts
@interface AlertWindow: UIWindow
+ (void)presentAlertWithTitle:(NSString *)title message:(NSString *)message;
@end
@implementation AlertWindow
+ (AlertWindow *)sharedInstance
{
static AlertWindow *sharedInstance;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedInstance = [[AlertWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];
});
return sharedInstance;
}
+ (void)presentAlertWithTitle:(NSString *)title message:(NSString *)message
{
// Using a separate window to solve "Warning: Attempt to present <UIAlertController> on <UIViewController> whose view is not in the window hierarchy!"
UIWindow *shared = AlertWindow.sharedInstance;
shared.userInteractionEnabled = YES;
UIViewController *root = shared.rootViewController;
UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert];
alert.modalInPopover = true;
[alert addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
shared.userInteractionEnabled = NO;
[root dismissViewControllerAnimated:YES completion:nil];
}]];
[root presentViewController:alert animated:YES completion:nil];
}
- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
self.userInteractionEnabled = NO;
self.windowLevel = CGFLOAT_MAX;
self.backgroundColor = UIColor.clearColor;
self.hidden = NO;
self.rootViewController = UIViewController.new;
[NSNotificationCenter.defaultCenter addObserver:self
selector:@selector(bringWindowToTop:)
name:UIWindowDidBecomeVisibleNotification
object:nil];
return self;
}
/// Bring AlertWindow to top when another window is being shown.
- (void)bringWindowToTop:(NSNotification *)notification {
if (![notification.object isKindOfClass:[AlertWindow class]]) {
self.hidden = YES;
self.hidden = NO;
}
}
@end
[AlertWindow presentAlertWithTitle:@"My title" message:@"My message"];
self.tabBarController.dismiss(animated: false) {
self.start()
}
@IBAction func unwindFromAuthenticationWithSegue(segue: UIStoryboardSegue) {
self.shouldSegueToMainTabBar = true
}
@IBAction func unwindFromForgetPasswordWithSegue(segue: UIStoryboardSegue) {
self.shouldSegueToLogin = true
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let storyboard = UIStoryboard(name: "Main", bundle: nil)
if self.shouldSegueToMainTabBar {
let mainTabBarController = storyboard.instantiateViewController(withIdentifier: "mainTabBarVC") as! MainTabBarController
self.present(mainTabBarController, animated: true)
self.shouldSegueToMainTabBar = false
}
if self.shouldSegueToLogin {
let loginController = storyboard.instantiateViewController(withIdentifier: "loginVC") as! LogInViewController
self.present(loginController, animated: true)
self.shouldSegueToLogin = false
}
}
let viewController = self // I had viewController passed in as a function,
// but otherwise you can do this
// Present the view controller
let currentViewController = UIApplication.shared.keyWindow?.rootViewController
currentViewController?.dismiss(animated: true, completion: nil)
if viewController.presentedViewController == nil {
currentViewController?.present(alert, animated: true, completion: nil)
} else {
viewController.present(alert, animated: true, completion: nil)
}
func updateView() {
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
// for programmatically presenting view controller
// present(viewController, animated: true, completion: nil)
//For Story board segue. you will also have to setup prepare segue for this to work.
self?.performSegue(withIdentifier: "Identifier", sender: nil)
}
}
if var topController = UIApplication.shared.keyWindow?.rootViewController {
while let presentedViewController = topController.presentedViewController {
topController = presentedViewController
}
topController.present(controller, animated: false, completion: nil)
// topController should now be your topmost view controller
}
override func viewDidLoad() {
super.viewDidLoad()
OperationQueue.main.addOperation {
// push or present the page inside this block
}
}
present(alert, animated: true, completion: nil)
DispatchQueue.main.async { [weak self] in
self?.present(alert, animated: true, completion: nil)
}