iOS Question [B4XPage] How to prevent page closing

[Alexander Stolte]

If the user closes the page but there are still unsaved changes, I would like to show the user a warning and give them the option to cancel the action.
How does this work with B4XPages?

Thanks

 

[LucaMs]

Private Sub B4XPage_CloseRequest As ResumableSub
    Dim sf As Object = xui.Msgbox2Async("Do you really want to close?", "Title", "Yes", "Cancel", "No", Null)
    Wait For (sf) Msgbox_Result (Result As Int)
    If Result <> xui.DialogResponse_Positive Then
        Return True
    End If
    
    Return False
End Sub

 

[Alexander Stolte]

B4XPage_CloseRequest

is unfortunately a B4A/B4J only event

[B4X] B4XPages - Cross platform and simple framework for managing multiple pages

B4XPages is a library that serves two purposes: 1. Make it simple to develop B4A apps by solving almost all of the challenges involved with Android complex activities life cycle. B4XPages makes B4A behave more similar to B4J and B4i where the new "B4XPage" element is a regular object that is...

www.b4x.com

 

[LucaMs]

is unfortunately a B4A/B4J only event

 

[Alessandro71]

I've been able to simulate the page close event on B4i with the following trick.
You can check if this allows the LucaMS suggestion to work for you

Sub B4XPages_Disappear
    #if B4i
    Dim PageClosed As Boolean = Not(B4XPages.GetManager.mStackOfPageIds.Contains(B4XPages.GetPageId(Me)))
    If PageClosed Then
        B4XPage_CloseRequest
    End If
    #end if
End Sub

 

[LucaMs]

I don't have B4i, so what I'm about to write could be completely wrong.

I suppose there is a close event in the Main of a B4i project. In this, you should detect which B4XPage is currently displayed, call one of its methods asking the user (...) and possibly show another B4XPage.

 

[LucaMs]

Dim PageClosed As Boolean = Not(B4XPages.GetManager.mStackOfPageIds.Contains(B4XPages.GetPageId(Me)))

When that event is triggered on that page (even several times) it will always be in the stack, otherwise how could it be triggered?

 

[LucaMs]

When that event is triggered on that page (even several times) it will always be in the stack, otherwise how could it be triggered?

 

[Alessandro71]

the Disappear event is triggered _after_ the page has been closed, so it's not on the stack anymore.
maybe not exactly what Alexander was searching, but it could be starting point

 

[LucaMs]

the Disappear event is triggered _after_ the page has been closed, so it's not on the stack anymore.

Are you sure? Because the purpose of the event is to allow you to perform some operation, so theoretically the page should only be deleted from the stack at the "End Sub".

 

[Erel]

You can prevent the user from closing the page, but if this option is enabled then you aren't expected to cancel it. The user can close the page with a swipe.

B4XPages.GetNativeParent(Me).HideBackButton = True

Another option is to show the page with B4XPages.ShowPageAndRemovePreviousPages.

You can then add a "close" button and handle its event.