iOS13 Fix Modal lifecycle

[jfversluis]

Description of Change

Issues Resolved

• fixes [Bug] Page not popped on iOS 13 FormSheet swipe down #7878
• related iOS 13 Modal Compatibility updates #7145 & Force iOS 13 to use Full Screen for Modal #7172
• fixes [Bug] OnAppearing does not fire after a UIModalPresentationStyle.FormSheet Page is Dismissed #9307

API Changes

None

Platforms Affected

• iOS

Behavioral/Visual Changes

Modals presented as a FormSheet can now be swiped down and this will trigger the popped event for a modal within Xamarin.Forms. Because of that, the app continues to behave as intended instead of getting stuck because of the modal still being on the navigation stack.

Before/After Screenshots

Not applicable

Testing Procedure

PR Checklist

• Targets the correct branch
• Tests are passing (or failures are unrelated)

[jfversluis]

For this PR I did not revert the change in #7172 yet. That might however become part of this PR. Initially, this fixes #7878, but with that I think it also fixes the whole new iOS13 modal navigation.

I've implemented the new delegate for this and from there trigger the PopModalAsync within our codebase. This fixes the initial issue, but I think is also beneficial for handling the iOS13 modals.

I did not implement the animated bool for this, I believe swiping the FormSheet modal will always be animated anyway.

Since this might impact all of the modals in iOS, I'd like to get some eyes on this before we move forward on it. Also, additional testing with other modal presentation forms and modal presentation on iPad is still to be done.

[PureWeen]

Can't use because it uses XCode 11 APIs

We should just take this PR over and get it merged
#6558

I have some suggestions in there around the life cycle bits

[jfversluis]

I think this is now covered in #8551 so closing this one

[PureWeen]

@jfversluis can you rebase this to 4.5 and make any fixes necessary here to the appearing behavior?

[jfversluis]

@PureWeen done!

Extended the 7878 issue page a little to show it all works as expected now

[PureWeen]

Looks like something didn't go quite right with the rebase

[jfversluis]

🤔 should be fixed now

[PureWeen]

So, now it's failing from the VS 2017 checks we put in

So you'll need to if def for xcode11/xcode10

[jfversluis]

OK for real this time!

[matll42]

Hi, great thing that it is solved, I was getting my nerves on this since few days. Any idea, when we can except to get this deployed? (pre or not)

[jfversluis]

@matll42 we need one more approval for it to get merged. After that it should be available pretty soon in the next 4.5 service release and up

[matll42]

Sorry to insist
Is that present in nightly build? latest 4.5.0 NB is 4.5.0.125
I assume it's prior to 4.5.0.356 (stable)

In .125 modal opens with iOS12 behavior (and works)

[jfversluis]

I'm not sure if I understand you correctly, but the nightly only holds the vNext+1 version, which is the master branch AFAIK. So that would be 4.7 at this point in time. This fix is only merged in the 4.5 branch right now and wasn't merged up all the way to master yet.

Where did you see the 4.5 version that you are mentioning?

[matll42]

Too bad, I have to wait so.
I see it in Visual Studio when I upgrade packages. I added Xamarin-CI nugget source as in https://github.com/xamarin/Xamarin.Forms/wiki/Nightly-Builds

[jfversluis]

Great that you did and I love your enthusiasm, but unfortunately you will have to wait for the nightlies. Typically we merge up everything during Mondays. So come Tuesday there should be a nightly build with this fix.

You should be able to get the NuGet associated to this build, with the fix, here. You can install a NuGet package from disk as well :)