How to find current visible viewController in iOS - ios

Question

We know , if your viewController have been contain UINavigationController ,
you can find your current visible view controller by 'self.navigationController.visibleViewController' .
But I you present a view controller , how to find current visible controller ?
For Example :
code one :
------
AVClr *avclr = [[AVClr alloc]init] ;
AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate ;
appDelegate.window.rootViewController = avclr ;
[avclr presentViewController:loginNavClr animated:YES completion:nil] ;
---> now , display avclr
code two:
------
AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate ;
UIViewController *currentVisibleViewController = appDelegate.window.rootViewController ;
BVClr *bvclr = [[BVClr alloc]init] ;
[currentVisibleViewController presentViewController:bvclr animated:YES completion:nil] ;
---> now , display bvclr
code three:
------
AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate ;
UIViewController *currentVisibleViewController = appDelegate.window.rootViewController ;
CVClr *cvclr = [[CVClr alloc]init] ;
[currentVisibleViewController presentViewController:cvclr animated:YES completion:nil] ;
---> Error , can not display cvclr , because avclr is a rootViewController and avclr present bvclr , so display bvclr .
Question:
But we know ,code three in another .m file , so we don't know who is the rootViewController . so If I present cvclr , the result is unexpect !
In the circumstances ，how to display cvclr

Answer 1

-(UIViewController *)getVisibleViewController : (UIViewController *)rootViewController
{
UIViewController *rootVC = rootViewController;
if (rootVC == nil)
{
rootVC = [[[UIApplication sharedApplication] keyWindow] rootViewController];
}
if ([rootVC presentedViewController] == nil)
{
return rootVC;
}
if ([rootVC presentedViewController] != nil)
{
if ([[rootVC presentedViewController] isKindOfClass:UINavigationController.self]) {
UINavigationController *navigationController = (UINavigationController *)[rootVC presentedViewController];
return [[navigationController viewControllers] lastObject];
}
return [self getVisibleViewController : [rootVC presentedViewController]];
}
return nil;
}

Answer 2

to find current top view controller i used this method
- (UIViewController *)currentTopViewController
{
UIViewController *topVC = [[[[UIApplication sharedApplication] delegate] window] rootViewController];
while (topVC.presentedViewController)
{
topVC = topVC.presentedViewController;
}
if ([topVC isKindOfClass:[UINavigationController class]]) {
return [(UINavigationController *)topVC topViewController];
}
return topVC;
}

Answer 3

If you are presenting the next screen from that class then you don't need to fetch top view controller from UIWindow
Simply use this..
-----------------
AVClr *avclr = [[AVClr alloc]init];
[self presentViewController: avclr animated:YES completion:nil] ;
------------------------------
BVClr *bvclr = [[BVClr alloc]init] ;
[self.presentingViewControler presentViewController:bvclr animated:YES completion:nil] ;
------------------
CVClr *cvclr = [[CVClr alloc]init] ;
[self.presentingViewControler presentViewController:cvclr animated:YES completion:nil] ;

Answer 4

This code also check UITabbarViewContoller :
-(UIViewController *) getVisibleViewContoller {
UIViewController *rootViewController = UIApplication.sharedApplication.keyWindow.rootViewController;
if (!rootViewController) {
return nil;
}
if ([rootViewController isKindOfClass:[UITabBarController class]]) {
UITabBarController *tabbarVC = (UITabBarController *) rootViewController;
UIViewController *selectedVC = tabbarVC.selectedViewController;
if (selectedVC) {
if (![selectedVC isKindOfClass:[UINavigationController class]]) {
return selectedVC;
}
rootViewController = selectedVC;
}
}
if ([rootViewController isKindOfClass:[UINavigationController class]]) {
UINavigationController *navigationVC = (UINavigationController *) rootViewController;
if (navigationVC.topViewController) {
return navigationVC.topViewController;
}
return navigationVC.viewControllers.lastObject;
}
return rootViewController;
}