Fix iOS to key loaded/unloaded off a more correct platform event

[PureWeen]

Description

Ideally, we would key loaded/unloaded off of didMovetoWindow on UIView but there's no way (AFAIK) to reach this with overriding every single view.

The current implementation is fiddly and probably not reliable in all scenarios. Basically, it adds observables to various layers of the view and waits until one of those triggers to fire loaded.

https://github.com/dotnet/maui/blob/main/src/Core/src/Platform/iOS/ViewExtensions.cs#L659

Steps to Reproduce

• Run the MAUI repository
• subscribe to the loaded/unloaded event on any view
• break point the event
• see where it fires from.
• Figure out better code.

Some thoughts

• ~UIWindow has methods that will tell you any time a view is added. So, we could override this method and somehow use that to notify that the window has been attached to the view. One difficulty here is that we don't have a great way to get from platform views back to xplat views. We could track all platform views we create into a ConditionalWeakTable. There has been a few cases where being able to efficiently get from platform to xplat would be useful.~
  • It doesn't look like this is called for every view
• There's been frustrations about the timing of loaded already. We could just fire Loaded from the first measure or arrange call on a view (though this might mean there are some cases where loaded doesn't fire and it should). We could add this on top of the current solution to make it more robust.
• All of the layouts and content views we can provide overrides to so from the layouts we can propagate down when a view is added/removed from the window.
  • Not sure if this covers all cases

Link to public reproduction project repository

N/A

Version with bug

7.0 (current)

Last version that worked well

Unknown/Other

Affected platforms

iOS, macOS

Affected platform versions

ios/catalyst

Did you find any workaround?

No response

Relevant log output

No response

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[MichaelSL]

I wonder if this relates to the different behavior of Loaded event on Android and iOs. I have Shell application with several pages.

On Android:

1. application starts up with Page1
2. Page1 Loaded event handler fires
3. navigate to Page2
4. return to Page1
5. Page1 Loaded event doesn't fire

On iOS:

1. application starts up with Page1
2. Page1 Loaded event handler fires
3. navigate to Page2
4. return to Page1
5. Page1 Loaded event always fire

Basically, cross platform code needs workaround for iOs to avoid running same code multiple times. I wonder if this issue will help to make lifecycle events behavior more uniform?

[jstedfast]

This honestly doesn't feel like a "Good First Issue". It seems far too complicated for someone new to the team to even attempt.