Check if view controller is presented modally, or

问题:

How can I, in my view controller code, differentiate between:

• presented modally
• pushed on navigation stack

Both presentingViewController and isMovingToParentViewController are YES in both cases, so are not very helpful.

What complicates things is that my parent view controller is sometimes modal, on which the to be checked view controller is pushed.

It turns out my issue is that I embed my HtmlViewController in a UINavigationController which is then presented. That's why my own attempts and the good answers below were not working.

HtmlViewController*     termsViewController = [[HtmlViewController alloc] initWithDictionary:dictionary];
UINavigationController* modalViewController;

modalViewController = [[UINavigationController alloc] initWithRootViewController:termsViewController];
modalViewController.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentViewController:modalViewController
                   animated:YES
                 completion:nil];

I guess I'd better tell my view controller when it's modal, instead of trying to determine.

回答1:

Take with a grain of salt, didn't test.

- (BOOL)isModal {
     if([self presentingViewController])
         return YES;
     if([[[self navigationController] presentingViewController] presentedViewController] == [self navigationController])
         return YES;
     if([[[self tabBarController] presentingViewController] isKindOfClass:[UITabBarController class]])
         return YES;

    return NO;
 }

回答2:

You overlooked one method: isBeingPresented.

isBeingPresented is true when the view controller is being presented and false when being pushed.

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    if ([self isBeingPresented]) {
        // being presented
    } else if ([self isMovingToParentViewController]) {
        // being pushed
    } else {
        // simply showing again because another VC was dismissed
    }
}

回答3:

In Swift:

// MARK: - UIViewController implementation

extension UIViewController {

    var isModal: Bool {

        let presentingIsModal = presentingViewController != nil
        let presentingIsNavigation = navigationController?.presentingViewController?.presentedViewController == navigationController
        let presentingIsTabBar = tabBarController?.presentingViewController is UITabBarController

        return presentingIsModal || presentingIsNavigation || presentingIsTabBar || false
    }
}

回答4:

self.navigationController != nil would mean it's in a navigation stack.

In order to handle the case that the current view controller is pushed while the navigation controller is presented modally, I have added some lines of code to check if the current view controller is the root controller in the navigation stack .

extension UIViewController{
func isModal() -> Bool {

    if let navigationController = self.navigationController{
        if navigationController.viewControllers.first != self{
            return false
        }
    }

    if self.presentingViewController != nil {
        return true
    }

    if self.navigationController?.presentingViewController?.presentedViewController == self.navigationController  {
        return true
    }

    if self.tabBarController?.presentingViewController is UITabBarController {
        return true
    }

    return false
   }
}

回答5:

Swift 3
Here is solution that addresses the issue mentioned with previous answers, when isModal() returns true if pushed UIViewController is in a presented UINavigationController stack.

extension UIViewController {
    var isModal: Bool {
        if let index = navigationController?.viewControllers.index(of: self), index > 0 {
            return false
        } else if presentingViewController != nil {
            return true
        } else if navigationController?.presentingViewController?.presentedViewController == navigationController  {
            return true
        } else if tabBarController?.presentingViewController is UITabBarController {
            return true
        } else {
            return false
        }
    }
}

It does work for me so far. If some optimizations, please share.

回答6:

Swift 4

var isModal: Bool {
    return presentingViewController != nil ||
           navigationController?.presentingViewController?.presentedViewController === navigationController ||
           tabBarController?.presentingViewController is UITabBarController
}

回答7:

self.navigationController != nil would mean it's in a navigation stack.

回答8:

As many folks here suggest, that "checking" methods don't work well for all cases, in my project I've come up with solution to manage that manually. The point is, we usually manage presentation on our own - this is not what happens behind the scene and we must to introspect.

DEViewController.h file:

#import <UIKit/UIKit.h>

// it is a base class for all view controllers within a project
@interface DEViewController : UIViewController 

// specify a way viewcontroller, is presented  by another viewcontroller
// the presented view controller should manually assign the value to it
typedef NS_ENUM(NSUInteger, SSViewControllerPresentationMethod) {
    SSViewControllerPresentationMethodUnspecified = 0,
    SSViewControllerPresentationMethodPush,
    SSViewControllerPresentationMethodModal,
};
@property (nonatomic) SSViewControllerPresentationMethod viewControllerPresentationMethod;

// other properties/methods...
@end

The presentations now could be managed this way:

pushed on navigation stack:

// DETestViewController inherits from DEViewController
DETestViewController *vc = [DETestViewController new];
vc.viewControllerPresentationMethod = SSViewControllerPresentationMethodPush;
[self.navigationController pushViewController:vc animated:YES];

presented modally with navigation:

DETestViewController *vc = [DETestViewController new];
vc.viewControllerPresentationMethod = SSViewControllerPresentationMethodModal;
UINavigationController *nav = [[UINavigationController alloc]
                               initWithRootViewController:vc];
[self presentViewController:nav animated:YES completion:nil];

presented modally:

DETestViewController *vc = [DETestViewController new];
vc.viewControllerPresentationMethod = SSViewControllerPresentationMethodModal;
[self presentViewController:vc animated:YES completion:nil];

Also, in DEViewController we could add a fallback to "checking" if the aforementioned property equals to SSViewControllerPresentationMethodUnspecified:

- (BOOL)isViewControllerPushed
{
    if (self.viewControllerPresentationMethod != SSViewControllerPresentationMethodUnspecified) {
        return (BOOL)(self.viewControllerPresentationMethod == SSViewControllerPresentationMethodPush);
    }

    else {
        // fallback to default determination method
        return (BOOL)self.navigationController.viewControllers.count > 1;
    }
}

回答9:

Assuming that all viewControllers that you present modally are wrapped inside a new navigationController (which you should always do anyway), you can add this property to your VC.

private var wasPushed: Bool {
    guard let vc = navigationController?.viewControllers.first where vc == self else {
        return true
    }

    return false
}

回答10:

To detect your controller is pushed or not just use below code in anywhere you want:

if ([[[self.parentViewController childViewControllers] firstObject] isKindOfClass:[self class]]) {

    // Not pushed
}
else {

    // Pushed
}

I hope this code can help anyone...

回答11:

If you are using ios 5.0 or later than please use this code

-(BOOL)isPresented
{
if ([self isBeingPresented]) {
    // being presented
     return YES;
} else if ([self isMovingToParentViewController]) {
    // being pushed
     return NO;
} else {
    // simply showing again because another VC was dismissed
     return NO;
}

}

回答12:

if let navigationController = self.navigationController, navigationController.isBeingPresented {
    // being presented
}else{
    // being pushed
}

回答13:

id presentedController = self.navigationController.modalViewController;
if (presentedController) {
     // Some view is Presented
} else {
     // Some view is Pushed
}

This will let you know if viewController is presented or pushed

回答14:

For some one who's wondering, How to tell ViewController that it is being presented

if A is presenting/pushing B

1. Define an enum and property in B

   enum ViewPresentationStyle {
       case Push
       case Present
   }
   
   //and write property 
   
   var vcPresentationStyle : ViewPresentationStyle = .Push //default value, considering that B is pushed 
   

2. Now in A view controller, tell B if it is being presented/pushed by assigning presentationStyle

   func presentBViewController() {
       let bViewController = B()
       bViewController.vcPresentationStyle = .Present //telling B that it is being presented
       self.presentViewController(bViewController, animated: true, completion: nil)
   }
   

3. Usage in B View Controller

   override func viewDidLoad() {
       super.viewDidLoad()
   
       if self.vcPresentationStyle == .Present {
           //is being presented 
       }
       else {
           //is being pushed
       }
   
   }