[ios] Added 2 new mid alignment position in MGLAnnotationVerticalAlignment

[iDevid]

Added MidBottom and MidTop MGLAnnotationVerticalAlignment.

[iDevid]

@anandthakker

[1ec5]

Hi @iDevid, can you describe your use case, so that we can better understand what you’re trying to accomplish?

[iDevid]

I wanted to align the user annotation in the middle between the center of the frame and the bottom/top of the frame.

[iDevid]

@1ec5

[1ec5]

Have you considered changing the map view’s contentInsets property instead?

[iDevid]

@1ec5 of course, but when following the user, sometimes the map glitches and the insets goes back to default (I think because there is verticalAlignment center by default)

[iDevid]

As seen in the video, while following the user with contentInset, it will get restored to .center
ScreenRecording_03-13-2018 17-38-12.MP4.zip

[iDevid]

/cc @kkaefer @tobrun @fabian-guerra @asheemmamoowala

[1ec5]

As seen in the video, while following the user with contentInset, it will get restored to .center

That looks like unintended behavior. Perhaps we can address the issue you’re seeing without adding the API surface area. Would you mind opening a separate issue about it? If the problem only occurs with certain settings or when setting insets at a particular time, please note that in the ticket. Thanks!

[iDevid]

UP

[1ec5]

First of all, thank you for taking the time to propose these changes. I agree that the user puck’s default positioning isn’t ideal for every application, but I don’t think we’re going to want to add these halfway alignment values. The user puck is supposed to respect the map view’s content inset. Following #7716, it should respect the containing view controller’s layout guides, and following #12147, it’ll also respect the safe area.

If there are bugs in how the map view interacts with content insets, layout guides, or the safe area, I suspect #6566 has something to do with it. Please open a new issue about it with a reproducible test case.

Ultimately, it was a mistake for us to expose something as simplistic as MGLAnnotationVerticalAlignment. #12203 would supplant this enumeration with a delegate method, which you could use to decide exactly where on screen you want the user puck (and the camera’s focal point) to appear.

Feel free to open a new PR for either the design in #12203 or a different design that gives developers more control over the exact positioning.