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
伟大的解决方案在Swift,实现在AppDelegate
func getTopViewController()->UIViewController{
return topViewControllerWithRootViewController(UIApplication.sharedApplication().keyWindow!.rootViewController!)
}
func topViewControllerWithRootViewController(rootViewController:UIViewController)->UIViewController{
if rootViewController is UITabBarController{
let tabBarController = rootViewController as! UITabBarController
return topViewControllerWithRootViewController(tabBarController.selectedViewController!)
}
if rootViewController is UINavigationController{
let navBarController = rootViewController as! UINavigationController
return topViewControllerWithRootViewController(navBarController.visibleViewController)
}
if let presentedViewController = rootViewController.presentedViewController {
return topViewControllerWithRootViewController(presentedViewController)
}
return rootViewController
}
其他回答
我认为Rajesh的解决方案几乎是完美的,但我认为从上到下遍历子视图更好,我改为如下:
+ (UIViewController *)topViewController:(UIViewController *)viewController{
if (viewController.presentedViewController)
{
UIViewController *presentedViewController = viewController.presentedViewController;
return [self topViewController:presentedViewController];
}
else if ([viewController isKindOfClass:[UITabBarController class]])
{
UITabBarController *tabBarController = (UITabBarController *)viewController;
return [self topViewController:tabBarController.selectedViewController];
}
else if ([viewController isKindOfClass:[UINavigationController class]])
{
UINavigationController *navController = (UINavigationController *)viewController;
return [self topViewController:navController.visibleViewController];
}
// Handling UIViewController's added as subviews to some other views.
else {
NSInteger subCount = [viewController.view subviews].count - 1;
for (NSInteger index = subCount; index >=0 ; --index)
{
UIView *view = [[viewController.view subviews] objectAtIndex:index];
id subViewController = [view nextResponder]; // Key property which most of us are unaware of / rarely use.
if ( subViewController && [subViewController isKindOfClass:[UIViewController class]])
{
return [self topViewController:subViewController];
}
}
return viewController;
}
}
如果根控制器是一个导航控制器,找到顶部可见控制器的正确方法是:
UIViewController *rootVC = [[UIApplication sharedApplication] keyWindow].rootViewController;
if ([rootVC respondsToSelector:@selector(visibleViewController)])
{
UIViewController *topVC = [(UINavigationController *)rootVC visibleViewController];
// do your thing with topVC
}
以下是UINavigationController.h的节选:
@property(nonatomic,readonly,retain) UIViewController *topViewController; // The top view controller on the stack.
@property(nonatomic,readonly,retain) UIViewController *visibleViewController; // Return modal view controller if it exists. Otherwise the top view controller.
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;
}
下面两个函数可以帮助在视图控制器堆栈中找到topViewController。以后可能需要自定义,但是对于这段代码来说,理解topViewController或viewcontroller堆栈的概念非常棒。
- (UIViewController*)findTopViewController {
id topControler = [self topMostController];
UIViewController* topViewController;
if([topControler isKindOfClass:[UINavigationController class]]) {
topViewController = [[(UINavigationController*)topControler viewControllers] lastObject];
} else if ([topControler isKindOfClass:[UITabBarController class]]) {
//Here you can get reference of top viewcontroller from stack of viewcontrollers on UITabBarController
} else {
//topController is a preented viewController
topViewController = (UIViewController*)topControler;
}
//NSLog(@"Top ViewController is: %@",NSStringFromClass([topController class]));
return topViewController;
}
- (UIViewController*)topMostController
{
UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (topController.presentedViewController) {
topController = topController.presentedViewController;
}
//NSLog(@"Top View is: %@",NSStringFromClass([topController class]));
return topController;
}
你可以使用[viewController Class]方法找出一个viewController的类的类型。
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() {
}