Update annotations and annotation images dynamically

[1ec5]

MGLMapView observes changes to the coordinate property of each MGLAnnotation added to it. Changing the coordinate property in a KVO-compliant way causes the annotation to be relocated and its callout view, if present, to be dismissed. To avoid observing the same annotation twice yet also avoid expensive lookups when adding or removing annotations, MGLMapView indexes added point annotations in an NSMutableSet.

Added the ability to delete an unused annotation image’s images on iOS. (The OS X SDK doesn’t yet support changing an annotation image’s image.) When you nil out the image of an MGLAnnotationImage, MGLMapView deletes the sprite from the style and resets any annotation associated with the MGLAnnotationImage instance to use the default red pin icon under the hood. The annotation remains associated with the MGLAnnotationImage, which comes in handy in the event that the annotation image’s image becomes non-nil.

In iosapp, tapping a callout view moves the selected annotation to the center of the screen and deselects it. Deselecting an annotation resets its image to the default; deselecting it again restores the image.

Fixes #1980.

/ref #3185
/cc @boundsj @friedbunny

[friedbunny]

I'm not seeing a new handler for this action.

[1ec5]

Oops, I didn’t end up needing that action. I’ll remove it.

[1ec5]

Implementing the annotation replacement in mbgl, as in #3885, would probably be more efficient.

[1ec5]

Moving to 3.3.0 milestone in light of #4556.

[1ec5]

I added support for atomically relocating an annotation without having to replace the annotation outright. The PR description has been updated.

[boundsj]

Great! I made a similar refactor on my annotation branch. This is better and includes the new and better property name on MGLAnnotationContext

[boundsj]

👍 this looks great! I will base the change I'm about to make for a custom view off of this branch until it lands in master.

[t-yoshii]

Hi,
Does this feature cover MGLPolyLine?

Removing MGLPolyline object from MGLMapView causes app crash.

override func viewDidLoad() {
    super.viewDidLoad()

    mapView = MGLMapView(frame: view.bounds)
    mapView.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]

    var coordinates: [CLLocationCoordinate2D] = [CLLocationCoordinate2DMake(40.7326808, -73.9843407), CLLocationCoordinate2DMake(40.7326808, -73.9943407)]
    polyline = MGLPolyline(coordinates: &coordinates, count: 2)

    // set the map's center coordinate
    mapView.setCenterCoordinate(CLLocationCoordinate2D(latitude: 40.7326808,
        longitude: -73.9843407),
        zoomLevel: 12, animated: false)

    mapView.addAnnotation(polyline!)

    mapView.removeAnnotation(polyline!)  /// CRASH HAPPENS HERE!
    view.addSubview(mapView)
}

Exception detail:

2016-04-20 18:11:23.932 MapboxTest[364:56042] *** Terminating app due to uncaught exception 'NSRangeException', reason: 'Cannot remove an observer <MGLMapView 0x15ee754d0> for the key path "coordinate" from <MGLPolyline 0x15ee602a0> because it is not registered as an observer.'

[1ec5]

@t-yoshii, good catch. It still isn’t possible to change a polyline or polygon’s location or form on the fly. A fix for this crash is in #4766.

[t-yoshii]

@1ec5 Thank you for your reply! I will try the version which includes #4766.

[incanus]

@1ec5 I realized I undid your deselection behavior over in #5786 (see opening description). How important is that to bring back?

[1ec5]

Here’s what this PR implemented originally:

In iosapp, tapping a callout view moves the selected annotation to the center of the screen and deselects it. Deselecting an annotation resets its image to the default; deselecting it again restores the image.

We should have something to exercise both pieces of functionality, but feel free to find a better way to exercise them.