Question

我试图在聊天屏幕上隐藏UIAlertView，并在用户收到消息时在所有其他页面上显示。

知道如何从appDelegate找到当前的控制器吗？

我是一个目标C还在学习的菜鸟。

-(void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {

if (isOnInstantMessagingScreen) {

   //Show nothing
}

else {

UIApplicationState state = [application applicationState];
   if (state == UIApplicationStateActive) {
    NSString *cancelTitle = @"Close";
    NSString *showTitle = @"View";
    NSString *message = [[userInfo valueForKey:@"aps"] valueForKey:@"alert"];
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"New Message!"
                                                        message:message
                                                       delegate:self
                                              cancelButtonTitle:cancelTitle
                                              otherButtonTitles:showTitle, nil];
    [alertView show];

}



}

我发现了这个：

 - (UIViewController *)topViewController{
  return [self topViewController:[UIApplication     sharedApplication].keyWindow.rootViewController];
      }

     - (UIViewController *)topViewController:(UIViewController *)rootViewController
  {
  if ([rootViewController isKindOfClass:[UINavigationController class]]) {
    UINavigationController *navigationController = (UINavigationController          *)rootViewController;
   return [self topViewController:[navigationController.viewControllers     lastObject]];
}
     if ([rootViewController isKindOfClass:[UITabBarController class]]) {
UITabBarController *tabController = (UITabBarController *)rootViewController;
return [self topViewController:tabController.selectedViewController];
}
    if (rootViewController.presentedViewController) {
return [self topViewController:rootViewController];
}
 return rootViewController;
   }

我的消息controller = MessageViewController

我如何调用此代码？

Answer 1

如果你没有使用导航控制器，那么你可以通过以下方式获得：

<?php
use Doctrine\Common\Annotations\AnnotationRegistry;
use Composer\Autoload\ClassLoader;

error_reporting(error_reporting() & ~E_USER_DEPRECATED);

$loader = require __DIR__.'/../vendor/autoload.php';
AnnotationRegistry::registerLoader(array($loader, 'loadClass'));

return $loader;

如果您查看控制器是在导航控制器下托管，则需要额外的步骤。

id myCurrentController = self.window.rootViewController; //you can cast it

Answer 2

解决相同的问题，将控制器嵌套在UITabBarController和UINavigationController中，我做了这个（通用）扩展名：

import Foundation
import UIKit

extension AppDelegate {
    func findController<T: UIViewController>(_ type: T.Type) -> T? {
        let controller = window?.rootViewController
        return findController(type: type, controller)
    }

    fileprivate func findController<T: UIViewController>(type: T.Type, _ controller: UIViewController?) -> T? {
        guard controller != nil else {
            return nil
        }

        return controller as? T ??
            findController(type: type, nestedIn: controller as? UINavigationController) ??
            findController(type: type, nestedIn: controller as? UITabBarController)
    }

    fileprivate func findController<T: UIViewController>(type: T.Type, nestedIn controller: UINavigationController?) -> T? {
        return findController(type: type, controller?.topViewController)
    }

    fileprivate func findController<T: UIViewController>(type: T.Type, nestedIn controller: UITabBarController?) -> T? {
        return findController(type: type, controller?.childViewControllers[controller!.selectedIndex])
    }
}

像这样使用：

if let controller = findController(YouViewController.self) {
    controller.whateverYouNeed()
}

如何从Appdelegate.m获取当前控制器

2 个答案: