iOS Question Back Button and Back transition detection


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My B4A app has many pages which the user swipes left or right to access. The app uses the panel touch event to manage this.

For B4i I see that for transitioning to pages to the left I can use the Back key function on the top bar to do a similar function but with a nice split transition between the two pages as one moves off to the right and the new on comes in from the left.

This happens by either tapping the top bar left Back button or by swiping from off screen left to on screen towards the right.

This is all well and good. But I need to know which page is currently being displayed so I can update the data on the page as new data comes into the app.

How can I detect that the back button/function has been activated and a new page (previous page) is being displayed? Or how can I tell which page is being displayed when my app did not load the page but it was done automatically by the Back key/function.

The BarButtonClick only seems to work for buttons added to the bar and that would not work for the swipe activation of the Back function even if tapping the back button did generate a Click event.

Solution is to use Page1_Appear to update the app so it knows which page is currently visible.
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