在 iOS 中查找 rootViewController
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Finding the rootViewController in iOS
提问by Jim
In ShareKit, the code needs to determine where the rootViewController is so it can show a modal view. For some reason, the code is failing in iOS 5:
在 ShareKit 中，代码需要确定 rootViewController 的位置，以便它可以显示模态视图。出于某种原因，代码在 iOS 5 中失败了：
// Try to find the root view controller programmically
// Find the top window (that is not an alert view or other window)
UIWindow *topWindow = [[UIApplication sharedApplication] keyWindow];
if (topWindow.windowLevel != UIWindowLevelNormal)
{
NSArray *windows = [[UIApplication sharedApplication] windows];
for(topWindow in windows)
{
if (topWindow.windowLevel == UIWindowLevelNormal)
break;
}
}
UIView *rootView = [[topWindow subviews] objectAtIndex:0];
id nextResponder = [rootView nextResponder];
if ([nextResponder isKindOfClass:[UIViewController class]])
self.rootViewController = nextResponder;
else
NSAssert(NO, @"ShareKit: Could not find a root view controller. You can assign one manually by calling [[SHK currentHelper] setRootViewController:YOURROOTVIEWCONTROLLER].");
This is hitting the assert.
这是命中断言。
What is wrong with simply using the following code, instead?
简单地使用以下代码有什么问题呢？
rootViewController = [[[UIApplication sharedApplication] keyWindow] rootViewController];
This seems to be working fine. Will it fail under some conditions?
这似乎工作正常。在某些条件下它会失败吗？
回答by XJones
I'm not sure if you can rely on window.rootViewControllerb/c you don't have to set it. You can just add a subview to the window. The following seemed to work fine:
我不确定你是否可以依靠window.rootViewControllerb/c 你不必设置它。您可以只向窗口添加一个子视图。以下似乎工作正常：
id rootVC = [[[[[UIApplication sharedApplication] keyWindow] subviews] objectAtIndex:0] nextResponder];
回答by Esqarrouth
Swift way to do it, you can call this from anywhere:
快速的方式来做到这一点，你可以从任何地方调用它：
/// EZSwiftExtensions - Gives you the VC on top so you can easily push your popups
public var topMostVC: UIViewController? {
var presentedVC = UIApplication.sharedApplication().keyWindow?.rootViewController
while let pVC = presentedVC?.presentedViewController {
presentedVC = pVC
}
if presentedVC == nil {
print("EZSwiftExtensions Error: You don't have any views set. You may be calling them in viewDidLoad. Try viewDidAppear instead.")
}
return presentedVC
}
Its included as a standard function in:
它作为标准功能包含在：
回答by Pedro Trujillo
This worked for me:
这对我有用：
UIViewController * rootViewController = (UIViewController *)[[[UIApplication.sharedApplication.keyWindow subviews] firstObject];
