刚开始使用Xcode 4.5，我在控制台得到了这个错误:
警告:试图在< ViewController: 0x1ec3e000>上显示< finishViewController: 0x1e56e0a0 >，其视图不在窗口层次结构中!
视图仍在显示，应用程序中的一切都在正常工作。这是iOS 6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:@"finishViewController"];
[self presentViewController:finished animated:NO completion:NULL];
当前回答
要将任何子视图显示到主视图，请使用以下代码
UIViewController *yourCurrentViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (yourCurrentViewController.presentedViewController)
{
yourCurrentViewController = yourCurrentViewController.presentedViewController;
}
[yourCurrentViewController presentViewController:composeViewController animated:YES completion:nil];
对于从主视图中解散任何子视图，请使用以下代码
UIViewController *yourCurrentViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (yourCurrentViewController.presentedViewController)
{
yourCurrentViewController = yourCurrentViewController.presentedViewController;
}
[yourCurrentViewController dismissViewControllerAnimated:YES completion:nil];
其他回答
它工作得很好，试试这个。链接
UIViewController *top = [UIApplication sharedApplication].keyWindow.rootViewController;
[top presentViewController:secondView animated:YES completion: nil];
我修复了这个错误，将最顶部的视图控制器存储为常量，这是在rootViewController的while循环中发现的:
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
}
我在Swift 4.2上也有类似的问题，但我的观点没有从视图周期中呈现出来。我发现我有多个segue要同时呈现。所以我使用dispatchAsyncAfter。
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)
}
}
我也有同样的问题。问题是，performSegueWithIdentifier是由通知触发的，只要我把通知放在主线程上，警告消息就消失了。
斯威夫特5
我在viewDidLayoutSubviews中调用present，因为在viewDidAppear中呈现会在模态加载之前导致视图控制器的瞬间显示，这看起来像一个丑陋的故障
确保检查窗口是否存在并只执行一次代码
var alreadyPresentedVCOnDisplay = false
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
// we call present in viewDidLayoutSubviews as
// presenting in viewDidAppear causes a split second showing
// of the view controller before the modal is loaded
guard let _ = view?.window else {
// window must be assigned
return
}
if !alreadyPresentedVCOnDisplay {
alreadyPresentedVCOnDisplay = true
present(...)
}
}
