MGLMapView setCamera: does not check if new camera is the same as current camera

[friedbunny]

-[MGLMapView setCamera:withDuration:animationTimingFunction:] will happily pass along the current (unchanged) camera to _mbglMap->easeTo(), which eventually sends false region change notifications.

This is especially bothersome when trying to set the camera in one of the region change delegate methods, because any call to a -[MGLMapView setCamera:] variant will keep looping but accomplish nothing.

Example:

#import "ViewController.h"
#import "Mapbox.h"

@interface ViewController () <MGLMapViewDelegate>

@property (nonatomic) MGLMapView *mapView;
@property (nonatomic) MGLMapCamera *camera;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    self.mapView = [[MGLMapView alloc] initWithFrame:self.view.bounds];
    self.mapView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    self.mapView.delegate = self;

    self.camera = [MGLMapCamera cameraLookingAtCenterCoordinate:CLLocationCoordinate2DMake(51.002040, 3.324372) fromDistance:20000 pitch:60 heading:180];

    [self.mapView setCamera:self.camera];

    [self.view addSubview:self.mapView];
}

- (void)mapView:(MGLMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
    NSLog(@"regionDidChangeAnimated");

    [self.mapView setCamera:self.camera];
//               withDuration:2
//    animationTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
}

@end

Which results in this strangely mesmerizing effect:

/cc @incanus @1ec5

[friedbunny]

The questions here are:

1. Where to validate that the camera needs changing — MGLMapView or some place in Transform?
2. How to efficiently perform this validation — which parameter changes matter?