[ios] Added "pending" completion blocks - to ensure that (for example…

…) annotation views are in the position they are expected to be at the end of an animation.

platform/ios/src/MGLMapView.mm

@@ -247,6 +247,7 @@ @interface MGLMapView () <UIGestureRecognizerDelegate,
 @property (nonatomic) NSMutableDictionary<NSString *, NSMutableArray<MGLAnnotationView *> *> *annotationViewReuseQueueByIdentifier;
 @property (nonatomic, readonly) BOOL enablePresentsWithTransaction;
 @property (nonatomic) UIImage *lastSnapshotImage;
+@property (nonatomic) NSMutableArray *pendingCompletionBlocks;
 
 /// Experimental rendering performance measurement.
 @property (nonatomic) BOOL experimental_enableFrameRateMeasurement;
@@ -612,6 +613,11 @@ - (void)commonInit
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willEnterForeground:) name:UIApplicationWillEnterForegroundNotification object:nil];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didBecomeActive:) name:UIApplicationDidBecomeActiveNotification object:nil];
+
+ // Pending completion blocks are called *after* annotation views have been updated
+ // in updateFromDisplayLink.
+ _pendingCompletionBlocks = [NSMutableArray array];
+
 
  // As of 3.7.5, we intentionally do not listen for `UIApplicationWillResignActiveNotification` or call `pauseRendering:` in response to it, as doing
  // so causes a loop when asking for location permission. See: https://github.com/mapbox/mapbox-gl-native/issues/11225
@@ -1033,6 +1039,33 @@ - (CGPoint)contentCenter
  return CGPointMake(CGRectGetMidX(contentFrame), CGRectGetMidY(contentFrame));
 }
 
+#pragma mark - Pending completion blocks
+
+- (void)processPendingBlocks
+{
+ NSArray *blocks = self.pendingCompletionBlocks;
+ self.pendingCompletionBlocks = [NSMutableArray array];
+
+ for (dispatch_block_t block in blocks)
+ {
+ block();
+ }
+}
+
+- (BOOL)addPendingBlock:(dispatch_block_t)block
+{
+ // Only add a block if the display link (that calls processPendingBlocks) is
+ // running, otherwise fall back to calling immediately.
+ BOOL addBlock = (_displayLink && !_displayLink.isPaused);
+
+ if (addBlock)
+ {
+ [self.pendingCompletionBlocks addObject:block];
+ }
+
+ return addBlock;
+}
+
 #pragma mark - Life Cycle -
 
 - (void)updateFromDisplayLink:(CADisplayLink *)displayLink
@@ -1057,7 +1090,7 @@ - (void)updateFromDisplayLink:(CADisplayLink *)displayLink
  return;
  }
 
- if (_needsDisplayRefresh)
+ if (_needsDisplayRefresh || (self.pendingCompletionBlocks.count > 0))
  {
  _needsDisplayRefresh = NO;
 
@@ -1066,6 +1099,13 @@ - (void)updateFromDisplayLink:(CADisplayLink *)displayLink
  [self updateAnnotationViews];
  [self updateCalloutView];
 
+ // Call any pending completion blocks. This is primarily to ensure
+ // that annotations are in the expected position after core rendering
+ // and map update.
+ //
+ // TODO: Consider using this same mechanism for delegate callbacks.
+ [self processPendingBlocks];
+
  _mbglView->display();
  }
 
@@ -1132,6 +1172,7 @@ - (void)validateDisplayLink
  {
  [_displayLink invalidate];
  _displayLink = nil;
+ [self processPendingBlocks];
  }
 }
 
@@ -1415,6 +1456,7 @@ - (void)pauseRendering:(__unused NSNotification *)notification
  [MGLMapboxEvents flush];
 
  _displayLink.paused = YES;
+ [self processPendingBlocks];
 
  if ( ! self.glSnapshotView)
  {
@@ -1467,6 +1509,11 @@ - (void)setHidden:(BOOL)hidden
 {
  super.hidden = hidden;
  _displayLink.paused = hidden;
+
+ if (hidden)
+ {
+ [self processPendingBlocks];
+ }
 }
 
 - (void)tintColorDidChange
@@ -3188,26 +3235,35 @@ - (void)_setCenterCoordinate:(CLLocationCoordinate2D)centerCoordinate edgePaddin
  animationOptions.duration.emplace(MGLDurationFromTimeInterval(duration));
  animationOptions.easing.emplace(MGLUnitBezierForMediaTimingFunction(function));
  }
+
+ dispatch_block_t pendingCompletion;
+
  if (completion)
  {
- animationOptions.transitionFinishFn = [completion]() {
+ __weak __typeof__(self) weakSelf = self;
+
+ pendingCompletion = ^{
+ if (![weakSelf addPendingBlock:completion])
+ {
+ completion();
+ }
+ };
+
+ animationOptions.transitionFinishFn = [pendingCompletion]() {
  // Must run asynchronously after the transition is completely over.
  // Otherwise, a call to -setCenterCoordinate: within the completion
  // handler would reenter the completion handler’s caller.
- dispatch_async(dispatch_get_main_queue(), ^{
- completion();
- });
+
+ dispatch_async(dispatch_get_main_queue(), pendingCompletion);
  };
  }
 
  MGLMapCamera *camera = [self cameraForCameraOptions:cameraOptions];
  if ([self.camera isEqualToMapCamera:camera] && UIEdgeInsetsEqualToEdgeInsets(_contentInset, insets))
  {
- if (completion)
+ if (pendingCompletion)
  {
- [self animateWithDelay:duration animations:^{
- completion();
- }];
+ [self animateWithDelay:duration animations:pendingCompletion];
  }
  return;
  }
@@ -3374,12 +3430,22 @@ - (void)_setVisibleCoordinates:(const CLLocationCoordinate2D *)coordinates count
  animationOptions.duration.emplace(MGLDurationFromTimeInterval(duration));
  animationOptions.easing.emplace(MGLUnitBezierForMediaTimingFunction(function));
  }
+
+ dispatch_block_t pendingCompletion;
+
  if (completion)
  {
- animationOptions.transitionFinishFn = [completion]() {
- dispatch_async(dispatch_get_main_queue(), ^{
+ __weak __typeof__(self) weakSelf = self;
+
+ pendingCompletion = ^{
+ if (![weakSelf addPendingBlock:completion])
+ {
  completion();
- });
+ }
+ };
+
+ animationOptions.transitionFinishFn = [pendingCompletion]() {
+ dispatch_async(dispatch_get_main_queue(), pendingCompletion);
  };
  }
 
@@ -3389,11 +3455,9 @@ - (void)_setVisibleCoordinates:(const CLLocationCoordinate2D *)coordinates count
  MGLMapCamera *camera = [self cameraForCameraOptions:cameraOptions];
  if ([self.camera isEqualToMapCamera:camera])
  {
- if (completion)
+ if (pendingCompletion)
  {
- [self animateWithDelay:duration animations:^{
- completion();
- }];
+ [self animateWithDelay:duration animations:pendingCompletion];
  }
  return;
  }
@@ -3534,22 +3598,30 @@ - (void)setCamera:(MGLMapCamera *)camera withDuration:(NSTimeInterval)duration a
  animationOptions.duration.emplace(MGLDurationFromTimeInterval(duration));
  animationOptions.easing.emplace(MGLUnitBezierForMediaTimingFunction(function));
  }
+
+ dispatch_block_t pendingCompletion;
+
  if (completion)
  {
- animationOptions.transitionFinishFn = [completion]() {
- dispatch_async(dispatch_get_main_queue(), ^{
+ __weak __typeof__(self) weakSelf = self;
+
+ pendingCompletion = ^{
+ if (![weakSelf addPendingBlock:completion])
+ {
  completion();
- });
+ }
+ };
+
+ animationOptions.transitionFinishFn = [pendingCompletion]() {
+ dispatch_async(dispatch_get_main_queue(), pendingCompletion);
  };
  }
 
  if ([self.camera isEqualToMapCamera:camera] && UIEdgeInsetsEqualToEdgeInsets(_contentInset, edgePadding))
  {
- if (completion)
+ if (pendingCompletion)
  {
- [self animateWithDelay:duration animations:^{
- completion();
- }];
+ [self animateWithDelay:duration animations:pendingCompletion];
  }
  return;
  }
@@ -3605,22 +3677,30 @@ - (void)_flyToCamera:(MGLMapCamera *)camera edgePadding:(UIEdgeInsets)insets wit
  animationOptions.minZoom = MGLZoomLevelForAltitude(peakAltitude, peakPitch,
  peakLatitude, self.frame.size);
  }
+
+ dispatch_block_t pendingCompletion;
+
  if (completion)
  {
- animationOptions.transitionFinishFn = [completion]() {
- dispatch_async(dispatch_get_main_queue(), ^{
+ __weak __typeof__(self) weakSelf = self;
+
+ pendingCompletion = ^{
+ if (![weakSelf addPendingBlock:completion])
+ {
  completion();
- });
+ }
+ };
+
+ animationOptions.transitionFinishFn = [pendingCompletion]() {
+ dispatch_async(dispatch_get_main_queue(), pendingCompletion);
  };
  }
 
  if ([self.camera isEqualToMapCamera:camera] && UIEdgeInsetsEqualToEdgeInsets(_contentInset, insets))
  {
- if (completion)
+ if (pendingCompletion)
  {
- [self animateWithDelay:duration animations:^{
- completion();
- }];
+ [self animateWithDelay:duration animations:pendingCompletion];
  }
  return;
  }