CODEWITHSUNDEEP
iosflutterflutter-layout
Junaid Tariq
Junaid Tariq

Reputation: 775

flutter's WillPopScope disables IOS back gestures, How to enable them?

I am creating an app where I have complete manual control over every back button press.

I basically have widgets/views changing in my app instead of the Navigator pushing and popping new screens.

I created a function where I am able to display views 1,2 and 3. and go back using the back button on android. however in case of iOS the back gesture does not work and I am unable to change views.

any workaround? Help would be appreciated

  Future<bool> goBackward(){
    if(_isButtonPressed) {
      if(currentView == 0)
        {
          return Future<bool>.value(true);
        }
      else if(currentView == 1)
        {
          currentView = 0;
          notifyListeners();
          return Future<bool>.value(false);
        }
      else
        {
          currentView = 2;
          notifyListeners();
          return Future<bool>.value(false);
        }
    }
  }

above is minimal version of code. when I return true that means I'm ready to Pop screen on back press

Upvotes: 9

Views: 7411

Answers (2)

Zsola
Zsola

Reputation: 21

Put this as your top-level widget, possibly inside the build function:

bool canNavigateBack = true;//This should come from a Stream/bloc/etc.

return WillPopScope(
        onWillPop: () {
          if (Platform.isAndroid) {
            if (canNavigateBack) {
              //Navigate back actions
            } else {
              //Show exit dialog, etc.
            }
          }
          return Future.value(false);
        },
        child: Platform.isIOS
            ? GestureDetector(
                onHorizontalDragEnd: (details) {
                  if (details.velocity.pixelsPerSecond.dx > 50) {
                    if (canNavigateBack) {
                      //Navigate back actions
                    } else {
                      //Show exit dialog, etc.
                    }
                  }
                },
                child: _anotherWidget())
            : _anotherWidget(),
      );

Note: Only works if you develop your app for Android / iOS.

Upvotes: 1

Junaid Tariq
Junaid Tariq

Reputation: 775

After searching on the web and trying numerous packages like cupertino_will_pop_scope and back_button_interceptor I found that none of them worked for my use case.

cupertino_will_pop_scope was a miss and hit thing so sometimes it worked and sometimes it didnt.

here is a solution for anyone who hasn't found an answer to this yet.

as I mentioned before the WillPopScope works perfectly on android so no need to change functionality over there.

for IOS however I used Gesture Detector to detect a swipe from left gesture and do my actions accordingly.

    if(!Platform.isIOS)
      {
        //When OS is Android return the view as is 
        return MyView;
      }
      else{
       //When OS is iOS return the view as is wrapped with GestreDetector

        return GestureDetector(
          onHorizontalDragUpdate: (details) {
            //set the sensitivity for your ios gesture anywhere between 10-50 is good

            int sensitivity = Integers().iosSwipeSensitivity;

            if (details.delta.dx > sensitivity) {
              //SWIPE FROM RIGHT DETECTION
              goBackward();
            }
          },
          child: MyView;
        );
      }

Upvotes: 17

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