Get the current displaying UIViewController on the screen in AppDelegate m

Question

The current UIViewController on the screen need to response to push-notifications from APNs  by setting some badge views  But how could I get the UIViewController in methodapplication didReceiveRemoteNotification  of AppDelegate m   I tried use self window rootViewController to get the current displaying UIViewController  it may be a UINavigationViewController or some other kind of view controller  And I find out that the visibleViewController property of UINavigationViewController can be used to get the UIViewController on the screen  But what could I do if it is not a UINavigationViewController   Any help is appreciated  The related code is as following   AppDelegate m      -  void application  UIApplication   application didReceiveRemoteNotification  NSDictionary   userInfo          I would like to find out which view controller is on the screen here       UIViewController  vc     UINavigationViewController   self window rootViewController visibleViewController        vc performSelector  selector handleThePushNotification   withObject userInfo           ViewControllerA m  -  void handleThePushNotification  NSDictionary   userInfo         set some badge view here

User · Answer

Code Here s an approach using the great switch-case syntax in Swift 3 4 5  import UIKit  extension UIWindow           Returns the currently visible view controller if any reachable within the window      public var visibleViewController  UIViewController            return UIWindow visibleViewController from  rootViewController                 Recursively follows navigation controllers  tab bar controllers and modal presented view controllers starting         from the given view controller to find the currently visible view controller                  - Parameters            - viewController  The view controller to start the recursive search from          - Returns  The view controller that is most probably visible on screen right now      public static func visibleViewController from viewController  UIViewController   - gt  UIViewController            switch viewController           case let navigationController as UINavigationController              return UIWindow visibleViewController from  navigationController visibleViewController    navigationController topViewController           case let tabBarController as UITabBarController              return UIWindow visibleViewController from  tabBarController selectedViewController           case let presentingViewController where viewController  presentedViewController    nil              return UIWindow visibleViewController from  presentingViewController  presentedViewController           default              return viewController                    The basic idea is the same as in zirinisp s answer  it s just using a more Swift 3  like syntax   Usage You probably want to create a file named UIWindowExt swift and copy the above extension code into it  On the call side it can be either used without any specific view controller  if let visibleViewCtrl   UIApplication shared keyWindow  visibleViewController          do whatever you want with your  visibleViewCtrl     Or if you know your visible view controller is reachable from a specific view controller  if let visibleViewCtrl   UIWindow visibleViewController from  specificViewCtrl           do whatever you want with your  visibleViewCtrl     I hope it helps

User · Answer

Mine is better      extension UIApplication       var visibleViewController   UIViewController            return keyWindow  rootViewController  topViewController          extension UIViewController       fileprivate var topViewController  UIViewController           switch self           case is UINavigationController              return  self as  UINavigationController  visibleViewController  topViewController    self         case is UITabBarController              return  self as  UITabBarController  selectedViewController  topViewController    self         default              return presentedViewController  topViewController    self

User · Answer

You can use the rootViewController also when your controller is not a UINavigationController   UIViewController  vc   self window rootViewController    Once you know the root view controller  then it depends on how you have built your UI  but you can possibly find out a way to navigate through the controllers hierarchy   If you give some more details about the way you defined your app  then I might give some more hint   EDIT   If you want the topmost view  not view controller   you could check      UIApplication sharedApplication  keyWindow  subviews  lastObject     although this view might be invisible or even covered by some of its subviews     again  it depends on your UI  but this might help

User · Answer

I created a category for UIApplication with visibleViewControllers property  The main idea is pretty simple  I swizzled viewDidAppear and viewDidDisappear methods in UIViewController  In viewDidAppear method viewController is added to stack  In viewDidDisappear method viewController is removed from stack  NSPointerArray is used instead of NSArray to store weak UIViewController   s references   This approach works for any viewControllers hierarchy   UIApplication VisibleViewControllers h   import  lt UIKit UIKit h gt    interface UIApplication  VisibleViewControllers    property  nonatomic  readonly  NSArray lt   kindof UIViewController   gt   visibleViewControllers    end   UIApplication VisibleViewControllers m   import  UIApplication VisibleViewControllers h   import  lt objc runtime h gt    interface UIApplication      property  nonatomic  readonly  NSPointerArray  visibleViewControllersPointers    end   implementation UIApplication  VisibleViewControllers   -  NSArray lt   kindof UIViewController   gt    visibleViewControllers       return self visibleViewControllersPointers allObjects     -  NSPointerArray   visibleViewControllersPointers       NSPointerArray  pointers   objc getAssociatedObject self   selector visibleViewControllersPointers        if   pointers            pointers    NSPointerArray weakObjectsPointerArray           objc setAssociatedObject self   selector visibleViewControllersPointers   pointers  OBJC ASSOCIATION RETAIN NONATOMIC             return pointers      end   implementation UIViewController  UIApplication VisibleViewControllers      void swizzleMethodWithOriginalSelector  SEL originalSelector swizzledSelector  SEL swizzledSelector       Method originalMethod   class getInstanceMethod self  originalSelector       Method swizzledMethod   class getInstanceMethod self  swizzledSelector       BOOL didAddMethod   class addMethod self  originalSelector  method getImplementation swizzledMethod   method getTypeEncoding swizzledMethod        if  didAddMethod            class replaceMethod self  swizzledSelector  method getImplementation originalMethod   method getTypeEncoding originalMethod          else           method exchangeImplementations originalMethod  swizzledMethod               void load       static dispatch once t onceToken      dispatch once  amp onceToken              self swizzleMethodWithOriginalSelector  selector viewDidAppear                                  swizzledSelector  selector uiapplication visibleviewcontrollers viewDidAppear              self swizzleMethodWithOriginalSelector  selector viewDidDisappear                                  swizzledSelector  selector uiapplication visibleviewcontrollers viewDidDisappear                -  void uiapplication visibleviewcontrollers viewDidAppear  BOOL animated         UIApplication sharedApplication  visibleViewControllersPointers addPointer    bridge void    Nullable self        self uiapplication visibleviewcontrollers viewDidAppear animated      -  void uiapplication visibleviewcontrollers viewDidDisappear  BOOL animated       NSPointerArray  pointers    UIApplication sharedApplication  visibleViewControllersPointers      for  int i   0  i  lt  pointers count  i              UIViewController  viewController    pointers pointerAtIndex i           if   viewController isEqual self                  pointers removePointerAtIndex i               break                       self uiapplication visibleviewcontrollers viewDidDisappear animated       end   https   gist github com medvedzzz e6287b99011f2437ac0beb5a72a897f0  Swift 3 version  UIApplication VisibleViewControllers swift  import UIKit  extension UIApplication        private struct AssociatedObjectsKeys           static var visibleViewControllersPointers    UIApplication visibleViewControllersPointers             fileprivate var visibleViewControllersPointers  NSPointerArray           var pointers   objc getAssociatedObject self   amp AssociatedObjectsKeys visibleViewControllersPointers  as  NSPointerArray          if  pointers    nil                pointers   NSPointerArray weakObjects               objc setAssociatedObject self   amp AssociatedObjectsKeys visibleViewControllersPointers  pointers  objc AssociationPolicy OBJC ASSOCIATION RETAIN NONATOMIC                    return pointers             var visibleViewControllers   UIViewController            return visibleViewControllersPointers allObjects as   UIViewController           extension UIViewController        private static func swizzleFunc withOriginalSelector originalSelector  Selector  swizzledSelector  Selector            let originalMethod   class getInstanceMethod self  originalSelector          let swizzledMethod   class getInstanceMethod self  swizzledSelector          let didAddMethod   class addMethod self  originalSelector  method getImplementation swizzledMethod   method getTypeEncoding swizzledMethod           if didAddMethod               class replaceMethod self  swizzledSelector  method getImplementation originalMethod   method getTypeEncoding originalMethod             else               method exchangeImplementations originalMethod  swizzledMethod                        override open class func initialize             if self    UIViewController self               return                   let swizzlingClosure                     UIViewController swizzleFunc withOriginalSelector   selector UIViewController viewDidAppear                                                swizzledSelector   selector uiapplication visibleviewcontrollers viewDidAppear                   UIViewController swizzleFunc withOriginalSelector   selector UIViewController viewDidDisappear                                                swizzledSelector   selector uiapplication visibleviewcontrollers viewDidDisappear                           swizzlingClosure             objc private func uiapplication visibleviewcontrollers viewDidAppear   animated  Bool            UIApplication shared visibleViewControllersPointers addPointer Unmanaged passUnretained self  toOpaque            uiapplication visibleviewcontrollers viewDidAppear animated              objc private func uiapplication visibleviewcontrollers viewDidDisappear   animated  Bool            let pointers   UIApplication shared visibleViewControllersPointers         for i in 0   lt pointers count               if let pointer   pointers pointer at  i                    let viewController   Unmanaged lt AnyObject gt  fromOpaque pointer  takeUnretainedValue   as  UIViewController                 if viewController isEqual self                        pointers removePointer at  i                      break                                                   uiapplication visibleviewcontrollers viewDidDisappear animated            https   gist github com medvedzzz ee6f4071639d987793977dba04e11399

User · Answer

Swift 2 0 version of jungledev s answer  func getTopViewController   - gt  UIViewController       var topViewController   UIApplication sharedApplication   delegate  window   rootViewController      while  topViewController presentedViewController    nil            topViewController   topViewController presentedViewController            return topViewController

User · Answer

Why not just handle the push notification code in the app delegate? Is it directly related to a view?

You can check if a UIViewController's view is currently visible by checking if it's view's window property has a value. See more here.

User · Answer

Simple extension for UIApplication in Swift (cares even about moreNavigationController within UITabBarController on iPhone):

extension UIApplication {
    class func topViewController(base: UIViewController? = UIApplication.sharedApplication().keyWindow?.rootViewController) -> UIViewController? {

        if let nav = base as? UINavigationController {
            return topViewController(base: nav.visibleViewController)
        }

        if let tab = base as? UITabBarController {
            let moreNavigationController = tab.moreNavigationController

            if let top = moreNavigationController.topViewController where top.view.window != nil {
                return topViewController(top)
            } else if let selected = tab.selectedViewController {
                return topViewController(selected)
            }
        }

        if let presented = base?.presentedViewController {
            return topViewController(base: presented)
        }

        return base
    }
}

Simple usage:

    if let rootViewController = UIApplication.topViewController() {
        //do sth with root view controller
    }

Works perfect:-)

UPDATE for clean code:

extension UIViewController {
    var top: UIViewController? {
        if let controller = self as? UINavigationController {
            return controller.topViewController?.top
        }
        if let controller = self as? UISplitViewController {
            return controller.viewControllers.last?.top
        }
        if let controller = self as? UITabBarController {
            return controller.selectedViewController?.top
        }
        if let controller = presentedViewController {
            return controller.top
        }
        return self
    }
}

User · Answer

You could also post a notification via NSNotificationCenter. This let's you deal with a number of situations where traversing the view controller hierarchy might be tricky - for example when modals are being presented, etc.

E.g.,

// MyAppDelegate.h
NSString * const UIApplicationDidReceiveRemoteNotification;

// MyAppDelegate.m
NSString * const UIApplicationDidReceiveRemoteNotification = @"UIApplicationDidReceiveRemoteNotification";

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

    [[NSNotificationCenter defaultCenter]
     postNotificationName:UIApplicationDidReceiveRemoteNotification
     object:self
     userInfo:userInfo];
}

In each of your View Controllers:

-(void)viewDidLoad {
    [[NSNotificationCenter defaultCenter] 
      addObserver:self
      selector:@selector(didReceiveRemoteNotification:)                                                  
      name:UIApplicationDidReceiveRemoteNotification
      object:nil];
}

-(void)viewDidUnload {
    [[NSNotificationCenter defaultCenter] 
      removeObserver:self
      name:UIApplicationDidReceiveRemoteNotification
      object:nil];
}

-(void)didReceiveRemoteNotification:(NSDictionary *)userInfo {
    // see http://stackoverflow.com/a/2777460/305149
   if (self.isViewLoaded && self.view.window) {
      // handle the notification
   }
}

You could also use this approach to instrument controls which need to update when a notification is received and are used by several view controllers. In that case, handle the add/remove observer calls in the init and dealloc methods, respectively.

User · Answer

I always love solutions that involve categories as they are bolt on and can be easily reused.

So I created a category on UIWindow. You can now call visibleViewController on UIWindow and this will get you the visible view controller by searching down the controller hierarchy. This works if you are using navigation and/or tab bar controller. If you have another type of controller to suggest please let me know and I can add it.

UIWindow+PazLabs.h (header file)

#import <UIKit/UIKit.h>

@interface UIWindow (PazLabs)

- (UIViewController *) visibleViewController;

@end

UIWindow+PazLabs.m (implementation file)

#import "UIWindow+PazLabs.h"

@implementation UIWindow (PazLabs)

- (UIViewController *)visibleViewController {
    UIViewController *rootViewController = self.rootViewController;
    return [UIWindow getVisibleViewControllerFrom:rootViewController];
}

+ (UIViewController *) getVisibleViewControllerFrom:(UIViewController *) vc {
    if ([vc isKindOfClass:[UINavigationController class]]) {
        return [UIWindow getVisibleViewControllerFrom:[((UINavigationController *) vc) visibleViewController]];
    } else if ([vc isKindOfClass:[UITabBarController class]]) {
        return [UIWindow getVisibleViewControllerFrom:[((UITabBarController *) vc) selectedViewController]];
    } else {
        if (vc.presentedViewController) {
            return [UIWindow getVisibleViewControllerFrom:vc.presentedViewController];
        } else {
            return vc;
        }
    }
}

@end

Swift Version

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
            }
        }
    }
}

User · Answer

zirinisp s Answer in Swift   extension UIWindow        func visibleViewController   - gt  UIViewController            if let rootViewController  UIViewController    self rootViewController               return UIWindow getVisibleViewControllerFrom rootViewController                    return nil            class func getVisibleViewControllerFrom vc UIViewController  - gt  UIViewController            if vc isKindOfClass UINavigationController self                 let navigationController   vc as UINavigationController             return UIWindow getVisibleViewControllerFrom  navigationController visibleViewController             else if vc isKindOfClass UITabBarController self                 let tabBarController   vc as UITabBarController             return UIWindow getVisibleViewControllerFrom tabBarController selectedViewController              else                if let presentedViewController   vc presentedViewController                    return UIWindow getVisibleViewControllerFrom presentedViewController presentedViewController                  else                    return vc                                    Usage    if let topController   window visibleViewController                 println topController

User · Answer

This worked for me  I have many targets that have different controllers so previous answers didn t seemed to work    first you want this inside your AppDelegate class   var window  UIWindow    then  in your function  let navigationController   window  rootViewController as  UINavigationController if let activeController   navigationController  visibleViewController       if activeController isKindOfClass  MyViewController              println  I have found my controller

User · Answer

Way less code than all other solutions   Objective-C version   -  UIViewController   getTopViewController       UIViewController  topViewController       UIApplication sharedApplication  delegate  window  rootViewController       while  topViewController presentedViewController  topViewController   topViewController presentedViewController       return topViewController      Swift 2 0 version   credit goes to Steve B   func getTopViewController   - gt  UIViewController       var topViewController   UIApplication sharedApplication   delegate  window   rootViewController      while  topViewController presentedViewController    nil            topViewController   topViewController presentedViewController            return topViewController     Works anywhere in your app  even with modals

User · Answer

Regarding NSNotificationCenter Post above (sorry can't find out where to post a comment under it...)

In case some were getting the -[NSConcreteNotification allKeys] error of sorts. Change this:

-(void)didReceiveRemoteNotification:(NSDictionary *)userInfo

to this:

-(void)didReceiveRemoteNotification:(NSNotification*)notif {
NSDictionary *dict = notif.userInfo;
}

User · Answer

Specify title to each ViewController and then get the title of current ViewController by the code given below.

-(void)viewDidUnload {
  NSString *currentController = self.navigationController.visibleViewController.title;

Then check it by your title like this

  if([currentController isEqualToString:@"myViewControllerTitle"]){
    //write your code according to View controller.
  }
}

User · Answer

I have found that iOS 8 has screwed everything up  In iOS 7 there is a new UITransitionView on the view hierarchy whenever you have a modally presented UINavigationController  Anyway  here s my code that finds gets the topmost VC  Calling getTopMostViewController should return a VC that you should be able to send a message like presentViewController animated completion  It s purpose is to get you a VC that you can use to present a modal VC  so it will most likely stop and return at container classes like UINavigationController and NOT the VC contained within them  Should not be hard to adapt the code to do that too  I ve tested this code in various situations in iOS 6  7 and 8  Please let me know if you find bugs      UIViewController   getTopMostViewController       UIWindow  window     UIApplication sharedApplication  keyWindow       if  window windowLevel    UIWindowLevelNormal            NSArray  windows     UIApplication sharedApplication  windows           for window in windows                if  window windowLevel    UIWindowLevelNormal                    break                                     for  UIView  subView in  window subviews                 UIResponder  responder    subView nextResponder              added this block of code for iOS 8 which puts a UITransitionView in between the UIWindow and the UILayoutContainerView         if   responder isEqual window                           this is a UITransitionView             if    subView subviews  count                                 UIView  subSubView    subView subviews  0     this should be the UILayoutContainerView                 responder    subSubView nextResponder                                    if  responder isKindOfClass  UIViewController class                  return  self topViewController   UIViewController    responder                        return nil        UIViewController    topViewController   UIViewController    controller       BOOL isPresenting   NO      do              this path is called only on iOS 6   so -presentedViewController is fine here          UIViewController  presented    controller presentedViewController           isPresenting   presented    nil          if presented    nil                controller   presented                   while  isPresenting        return controller

User · Answer

This is the best possible way that I have tried out  If it should help anyone        UIViewController   topMostController       UIViewController  topController    UIApplication sharedApplication  keyWindow rootViewController       while  topController presentedViewController            topController   topController presentedViewController             return topController

User · Answer

Always check your build configuration if you you are running your app with debug or release   IMPORTANT NOTE  You can t be able to test it without running your app in debug mode  This was my solution

User · Answer

extension UIApplication           The top most view controller     static var topMostViewController  UIViewController            return UIApplication shared keyWindow  rootViewController  visibleViewController          extension UIViewController           The visible view controller from a given view controller     var visibleViewController  UIViewController            if let navigationController   self as  UINavigationController               return navigationController topViewController  visibleViewController           else if let tabBarController   self as  UITabBarController               return tabBarController selectedViewController  visibleViewController           else if let presentedViewController   presentedViewController               return presentedViewController visibleViewController           else               return self                     With this you can easily get the top post view controller like so  let viewController   UIApplication topMostViewController   One thing to note is that if there s a UIAlertController currently being displayed  UIApplication topMostViewController will return a UIAlertController

User · Answer

Just addition to  zirinisp answer   Create a file  name it UIWindowExtension swift and paste the following snippet   import UIKit  public extension UIWindow       public var visibleViewController  UIViewController            return UIWindow getVisibleViewControllerFrom self rootViewController             public static func getVisibleViewControllerFrom vc  UIViewController   - gt  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   - gt  UIViewController        let appDelegate   UIApplication sharedApplication   delegate     if let window   appDelegate  window           return window  visibleViewController           return nil     Use it anywhere as   if let topVC   getTopViewController          Thanks to  zirinisp

[iphone] Get the current displaying UIViewController on the screen in AppDelegate.m

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