我遇到了一些情况,现在,它将是方便的,能够找到“最顶层”的视图控制器(一个负责当前视图),但还没有找到一种方法。
基本上,挑战是这样的:给定一个在一个类中执行,这个类不是一个视图控制器(或一个视图)[并且没有活动视图的地址],并且没有传递最顶层视图控制器的地址(或者,比如说,导航控制器的地址),是否有可能找到那个视图控制器?(如果是的话,是怎么做到的?)
或者,如果找不到,有没有可能找到最高处的风景?
我遇到了一些情况,现在,它将是方便的,能够找到“最顶层”的视图控制器(一个负责当前视图),但还没有找到一种方法。
基本上,挑战是这样的:给定一个在一个类中执行,这个类不是一个视图控制器(或一个视图)[并且没有活动视图的地址],并且没有传递最顶层视图控制器的地址(或者,比如说,导航控制器的地址),是否有可能找到那个视图控制器?(如果是的话,是怎么做到的?)
或者,如果找不到,有没有可能找到最高处的风景?
当前回答
这个答案包含了childViewControllers,并维护了一个干净易读的实现。
+ (UIViewController *)topViewController
{
UIViewController *rootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
return [rootViewController topVisibleViewController];
}
- (UIViewController *)topVisibleViewController
{
if ([self isKindOfClass:[UITabBarController class]])
{
UITabBarController *tabBarController = (UITabBarController *)self;
return [tabBarController.selectedViewController topVisibleViewController];
}
else if ([self isKindOfClass:[UINavigationController class]])
{
UINavigationController *navigationController = (UINavigationController *)self;
return [navigationController.visibleViewController topVisibleViewController];
}
else if (self.presentedViewController)
{
return [self.presentedViewController topVisibleViewController];
}
else if (self.childViewControllers.count > 0)
{
return [self.childViewControllers.lastObject topVisibleViewController];
}
return self;
}
其他回答
简单的扩展UIApplication在Swift:
注意:
它关心UITabBarController中的moreNavigationController
extension UIApplication {
class func topViewController(baseViewController: UIViewController? = UIApplication.sharedApplication().keyWindow?.rootViewController) -> UIViewController? {
if let navigationController = baseViewController as? UINavigationController {
return topViewController(navigationController.visibleViewController)
}
if let tabBarViewController = baseViewController as? UITabBarController {
let moreNavigationController = tabBarViewController.moreNavigationController
if let topViewController = moreNavigationController.topViewController where topViewController.view.window != nil {
return topViewController(topViewController)
} else if let selectedViewController = tabBarViewController.selectedViewController {
return topViewController(selectedViewController)
}
}
if let splitViewController = baseViewController as? UISplitViewController where splitViewController.viewControllers.count == 1 {
return topViewController(splitViewController.viewControllers[0])
}
if let presentedViewController = baseViewController?.presentedViewController {
return topViewController(presentedViewController)
}
return baseViewController
}
}
简单的用法:
if let topViewController = UIApplication.topViewController() {
//do sth with top view controller
}
最新Swift版本: 创建一个文件,命名为UIWindowExtension.swift,并粘贴以下代码片段:
import UIKit
public extension UIWindow {
public var visibleViewController: UIViewController? {
return UIWindow.getVisibleViewControllerFrom(self.rootViewController)
}
public static func getVisibleViewControllerFrom(_ vc: UIViewController?) -> UIViewController? {
if let nc = vc as? UINavigationController {
return UIWindow.getVisibleViewControllerFrom(nc.visibleViewController)
} else if let tc = vc as? UITabBarController {
return UIWindow.getVisibleViewControllerFrom(tc.selectedViewController)
} else {
if let pvc = vc?.presentedViewController {
return UIWindow.getVisibleViewControllerFrom(pvc)
} else {
return vc
}
}
}
}
func getTopViewController() -> UIViewController? {
let appDelegate = UIApplication.shared.delegate
if let window = appDelegate!.window {
return window?.visibleViewController
}
return nil
}
可以在任何地方使用:
if let topVC = getTopViewController() {
}
很多答案都是不完整的。虽然这是在Objective-C中,但这是我现在能把它们放在一起的最好的编译,作为一个非递归的块:
链接到Gist,以防修改:https://gist.github.com/benguild/0d149bb3caaabea2dac3d2dca58c0816 供参考/比较的代码:
UIViewController *(^topmostViewControllerForFrontmostNormalLevelWindow)(void) = ^UIViewController *{
// NOTE: Adapted from various stray answers here:
// https://stackoverflow.com/questions/6131205/iphone-how-to-find-topmost-view-controller/20515681
UIViewController *viewController;
for (UIWindow *window in UIApplication.sharedApplication.windows.reverseObjectEnumerator.allObjects) {
if (window.windowLevel == UIWindowLevelNormal) {
viewController = window.rootViewController;
break;
}
}
while (viewController != nil) {
if ([viewController isKindOfClass:[UITabBarController class]]) {
viewController = ((UITabBarController *)viewController).selectedViewController;
} else if ([viewController isKindOfClass:[UINavigationController class]]) {
viewController = ((UINavigationController *)viewController).visibleViewController;
} else if (viewController.presentedViewController != nil && !viewController.presentedViewController.isBeingDismissed) {
viewController = viewController.presentedViewController;
} else if (viewController.childViewControllers.count > 0) {
viewController = viewController.childViewControllers.lastObject;
} else {
BOOL repeat = NO;
for (UIView *view in viewController.view.subviews.reverseObjectEnumerator.allObjects) {
if ([view.nextResponder isKindOfClass:[UIViewController class]]) {
viewController = (UIViewController *)view.nextResponder;
repeat = YES;
break;
}
}
if (!repeat) {
break;
}
}
}
return viewController;
};
这是一个Swift的应用程序的实现与UINavigationController的根。
if let nav = UIApplication.sharedApplication().keyWindow?.rootViewController as? UINavigationController{
//get the current's navigation view controller
var vc = nav.topViewController
while vc?.presentedViewController != nil {
vc = vc?.presentedViewController
}
return vc
}
Swift 4.2中一个简洁而全面的解决方案,考虑了UINavigationControllers, UITabBarControllers, presenting和子视图控制器:
extension UIViewController {
func topmostViewController() -> UIViewController {
if let navigationVC = self as? UINavigationController,
let topVC = navigationVC.topViewController {
return topVC.topmostViewController()
}
if let tabBarVC = self as? UITabBarController,
let selectedVC = tabBarVC.selectedViewController {
return selectedVC.topmostViewController()
}
if let presentedVC = presentedViewController {
return presentedVC.topmostViewController()
}
if let childVC = children.last {
return childVC.topmostViewController()
}
return self
}
}
extension UIApplication {
func topmostViewController() -> UIViewController? {
return keyWindow?.rootViewController?.topmostViewController()
}
}
用法:
let viewController = UIApplication.shared.topmostViewController()