[ios] Added pending completion blocks (#15122)

4 files changed, 484 insertions, 31 deletions

diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index 5dc73de6d3..8edd8adc02 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -5,6 +5,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 ## master
 
 * Fixed an issue that caused the tilt gesture to trigger too easily and conflict with pinch or pan gestures. ([#15349](https://github.com/mapbox/mapbox-gl-native/pull/15349))
+* Fixed a bug with annotation view positions after camera transitions. ([#15122](https://github.com/mapbox/mapbox-gl-native/pull/15122/))
 
 ## 5.3.0
 
diff --git a/platform/ios/Integration Tests/MGLMapViewPendingBlockTests.m b/platform/ios/Integration Tests/MGLMapViewPendingBlockTests.m
new file mode 100644
index 0000000000..ad71dafd48
--- /dev/null
+++ b/platform/ios/Integration Tests/MGLMapViewPendingBlockTests.m
@@ -0,0 +1,367 @@
+#import "MGLMapViewIntegrationTest.h"
+#import "MGLTestUtility.h"
+
+@interface MGLMapView (MGLMapViewPendingBlockTests)
+@property (nonatomic) NSMutableArray *pendingCompletionBlocks;
+- (void)pauseRendering:(__unused NSNotification *)notification;
+@end
+
+@interface MGLMapViewPendingBlockTests : MGLMapViewIntegrationTest
+@property (nonatomic, copy) void (^observation)(NSDictionary*);
+@property (nonatomic) BOOL completionHandlerCalled;
+@end
+
+@implementation MGLMapViewPendingBlockTests
+
+- (void)testSetCenterCoordinate {
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            [strongSelf.mapView setCenterCoordinate:CLLocationCoordinate2DMake(10.0, 10.0)
+                                          zoomLevel:10.0
+                                          direction:0
+                                           animated:NO
+                                  completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+- (void)testSetCenterCoordinateAnimated {
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            [strongSelf.mapView setCenterCoordinate:CLLocationCoordinate2DMake(10.0, 10.0)
+                                          zoomLevel:10.0
+                                          direction:0
+                                           animated:YES
+                                  completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+- (void)testSetVisibleCoordinateBounds {
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            MGLCoordinateBounds unitBounds = MGLCoordinateBoundsMake(CLLocationCoordinate2DMake(0, 0), CLLocationCoordinate2DMake(1, 1));
+            [strongSelf.mapView setVisibleCoordinateBounds:unitBounds
+                                               edgePadding:UIEdgeInsetsZero
+                                                  animated:NO
+                                         completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+- (void)testSetVisibleCoordinateBoundsAnimated {
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            MGLCoordinateBounds unitBounds = MGLCoordinateBoundsMake(CLLocationCoordinate2DMake(0, 0), CLLocationCoordinate2DMake(1, 1));
+            [strongSelf.mapView setVisibleCoordinateBounds:unitBounds
+                                               edgePadding:UIEdgeInsetsZero
+                                                  animated:YES
+                                         completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+- (void)testSetCamera {
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            MGLCoordinateBounds unitBounds = MGLCoordinateBoundsMake(CLLocationCoordinate2DMake(0, 0), CLLocationCoordinate2DMake(1, 1));
+            MGLMapCamera *camera = [strongSelf.mapView cameraThatFitsCoordinateBounds:unitBounds];
+            
+            [strongSelf.mapView setCamera:camera withDuration:0.0 animationTimingFunction:nil completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+- (void)testSetCameraAnimated {
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            MGLCoordinateBounds unitBounds = MGLCoordinateBoundsMake(CLLocationCoordinate2DMake(0, 0), CLLocationCoordinate2DMake(1, 1));
+            MGLMapCamera *camera = [strongSelf.mapView cameraThatFitsCoordinateBounds:unitBounds];
+            
+            [strongSelf.mapView setCamera:camera withDuration:0.3 animationTimingFunction:nil completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+// Marked as pending due to https://github.com/mapbox/mapbox-gl-native/issues/15471
+- (void)testFlyToCameraPENDING {
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            MGLCoordinateBounds unitBounds = MGLCoordinateBoundsMake(CLLocationCoordinate2DMake(0, 0), CLLocationCoordinate2DMake(1, 1));
+            MGLMapCamera *camera = [strongSelf.mapView cameraThatFitsCoordinateBounds:unitBounds];
+            
+            [strongSelf.mapView flyToCamera:camera withDuration:0.0 completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+- (void)testFlyToCameraAnimated {
+    
+    __typeof__(self) weakSelf = self;
+
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            MGLCoordinateBounds unitBounds = MGLCoordinateBoundsMake(CLLocationCoordinate2DMake(0, 0), CLLocationCoordinate2DMake(1, 1));
+            MGLMapCamera *camera = [strongSelf.mapView cameraThatFitsCoordinateBounds:unitBounds];
+            
+            [strongSelf.mapView flyToCamera:camera withDuration:0.3 completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:nil];
+}
+
+
+#pragma mark - test interrupting regular rendering
+
+- (void)testSetCenterCoordinateSetHidden {
+    
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            [strongSelf.mapView setCenterCoordinate:CLLocationCoordinate2DMake(10.0, 10.0)
+                                          zoomLevel:10.0
+                                          direction:0
+                                           animated:NO
+                                  completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    dispatch_block_t addedToPending = ^{
+        __typeof__(self) strongSelf = weakSelf;
+
+        MGLTestAssert(strongSelf, !strongSelf.completionHandlerCalled);
+        
+        // Now hide the mapview
+        strongSelf.mapView.hidden = YES;
+        
+        MGLTestAssert(strongSelf, strongSelf.completionHandlerCalled);
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:addedToPending];
+}
+
+- (void)testSetCenterCoordinatePauseRendering {
+    
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            [strongSelf.mapView setCenterCoordinate:CLLocationCoordinate2DMake(10.0, 10.0)
+                                          zoomLevel:10.0
+                                          direction:0
+                                           animated:NO
+                                  completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    dispatch_block_t addedToPending = ^{
+        __typeof__(self) strongSelf = weakSelf;
+        
+        MGLTestAssert(strongSelf, !strongSelf.completionHandlerCalled);
+        
+        // Pause rendering, stopping display link
+        [strongSelf.mapView pauseRendering:nil];
+        
+        MGLTestAssert(strongSelf, strongSelf.completionHandlerCalled);
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:addedToPending];
+}
+
+- (void)testSetCenterCoordinateRemoveFromSuperview {
+    
+    __typeof__(self) weakSelf = self;
+    
+    void (^transition)(dispatch_block_t) = ^(dispatch_block_t completion) {
+        __typeof__(self) strongSelf = weakSelf;
+        
+        if (strongSelf) {
+            [strongSelf.mapView setCenterCoordinate:CLLocationCoordinate2DMake(10.0, 10.0)
+                                          zoomLevel:10.0
+                                          direction:0
+                                           animated:NO
+                                  completionHandler:completion];
+        }
+        else {
+            completion();
+        }
+    };
+    
+    dispatch_block_t addedToPending = ^{
+        __typeof__(self) strongSelf = weakSelf;
+        
+        MGLTestAssert(strongSelf, !strongSelf.completionHandlerCalled);
+        
+        // Remove from window, triggering validateDisplayLink
+        [strongSelf.mapView removeFromSuperview];
+        
+        MGLTestAssert(strongSelf, strongSelf.completionHandlerCalled);
+    };
+    
+    [self internalTestCompletionBlockAddedToPendingForTestName:NSStringFromSelector(_cmd)
+                                                    transition:transition
+                                          addToPendingCallback:addedToPending];
+}
+
+#pragma mark - Shared utility methods
+
+- (void)internalTestCompletionBlockAddedToPendingForTestName:(NSString *)testName
+                                                  transition:(void (^)(dispatch_block_t))transition
+                                        addToPendingCallback:(dispatch_block_t)addToPendingCallback {
+    
+    XCTestExpectation *expectation = [self expectationWithDescription:testName];
+    
+    __weak __typeof__(self) myself = self;
+    
+    dispatch_block_t block = ^{
+        myself.completionHandlerCalled = YES;
+        [expectation fulfill];
+    };
+    
+    XCTAssertNotNil(transition);
+    transition(block);
+    
+    XCTAssert(!self.completionHandlerCalled);
+    XCTAssert(self.mapView.pendingCompletionBlocks.count == 0);
+    
+    __block BOOL blockAddedToPendingBlocks = NO;
+    
+    // Observes changes to pendingCompletionBlocks (including additions)
+    self.observation = ^(NSDictionary *change){
+
+        NSLog(@"change = %@ count = %lu", change, myself.mapView.pendingCompletionBlocks.count);
+
+        NSArray *value = change[NSKeyValueChangeNewKey];
+        
+        MGLTestAssert(myself, [value isKindOfClass:[NSArray class]]);
+        
+        if (value.count > 0) {
+            MGLTestAssert(myself, [value containsObject:block]);            
+            MGLTestAssert(myself, !blockAddedToPendingBlocks);
+            if ([myself.mapView.pendingCompletionBlocks containsObject:block]) {
+                blockAddedToPendingBlocks = YES;
+                
+                if (addToPendingCallback) {
+                    addToPendingCallback();
+                }
+            }
+        }
+    };
+    
+    [self.mapView addObserver:self forKeyPath:@"pendingCompletionBlocks" options:NSKeyValueObservingOptionNew context:_cmd];
+    
+    [self waitForExpectations:@[expectation] timeout:0.5];
+    
+    XCTAssert(blockAddedToPendingBlocks);
+    XCTAssert(self.completionHandlerCalled);
+    XCTAssert(self.mapView.pendingCompletionBlocks.count == 0);
+    
+    [self.mapView removeObserver:self forKeyPath:@"pendingCompletionBlocks" context:_cmd];
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
+    if (self.observation) {
+        self.observation(change);
+    }
+}
+@end
diff --git a/platform/ios/ios.xcodeproj/project.pbxproj b/platform/ios/ios.xcodeproj/project.pbxproj
index 5a5cb00b49..018a5f9368 100644
--- a/platform/ios/ios.xcodeproj/project.pbxproj
+++ b/platform/ios/ios.xcodeproj/project.pbxproj
@@ -508,6 +508,7 @@
 		CA1B4A512099FB2200EDD491 /* MGLMapSnapshotterTest.m in Sources */ = {isa = PBXBuildFile; fileRef = CA1B4A502099FB2200EDD491 /* MGLMapSnapshotterTest.m */; };
 		CA34C9C3207FD272005C1A06 /* MGLCameraTransitionTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = CA34C9C2207FD272005C1A06 /* MGLCameraTransitionTests.mm */; };
 		CA4EB8C720863487006AB465 /* MGLStyleLayerIntegrationTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CA4EB8C620863487006AB465 /* MGLStyleLayerIntegrationTests.m */; };
+		CA4F3BDE230F74C3008BAFEA /* MGLMapViewPendingBlockTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CA4F3BDD230F74C3008BAFEA /* MGLMapViewPendingBlockTests.m */; };
 		CA55CD41202C16AA00CE7095 /* MGLCameraChangeReason.h in Headers */ = {isa = PBXBuildFile; fileRef = CA55CD3E202C16AA00CE7095 /* MGLCameraChangeReason.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		CA55CD42202C16AA00CE7095 /* MGLCameraChangeReason.h in Headers */ = {isa = PBXBuildFile; fileRef = CA55CD3E202C16AA00CE7095 /* MGLCameraChangeReason.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		CA65C4F821E9BB080068B0D4 /* MGLCluster.h in Headers */ = {isa = PBXBuildFile; fileRef = CA65C4F721E9BB080068B0D4 /* MGLCluster.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -1198,11 +1199,12 @@
 		CA1B4A502099FB2200EDD491 /* MGLMapSnapshotterTest.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MGLMapSnapshotterTest.m; sourceTree = "<group>"; };
 		CA34C9C2207FD272005C1A06 /* MGLCameraTransitionTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = MGLCameraTransitionTests.mm; sourceTree = "<group>"; };
 		CA4EB8C620863487006AB465 /* MGLStyleLayerIntegrationTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MGLStyleLayerIntegrationTests.m; sourceTree = "<group>"; };
+		CA4F3BDD230F74C3008BAFEA /* MGLMapViewPendingBlockTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MGLMapViewPendingBlockTests.m; sourceTree = "<group>"; };
 		CA55CD3E202C16AA00CE7095 /* MGLCameraChangeReason.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MGLCameraChangeReason.h; sourceTree = "<group>"; };
 		CA5E5042209BDC5F001A8A81 /* MGLTestUtility.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = MGLTestUtility.h; path = ../../darwin/test/MGLTestUtility.h; sourceTree = "<group>"; };
 		CA65C4F721E9BB080068B0D4 /* MGLCluster.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MGLCluster.h; sourceTree = "<group>"; };
-		CA86FF0D22D8D5A0009EB14A /* MGLNetworkConfigurationTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MGLNetworkConfigurationTests.m; sourceTree = "<group>"; };
 		CA6914B420E67F50002DB0EE /* MGLAnnotationViewIntegrationTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = MGLAnnotationViewIntegrationTests.mm; path = "Annotation Tests/MGLAnnotationViewIntegrationTests.mm"; sourceTree = "<group>"; };
+		CA86FF0D22D8D5A0009EB14A /* MGLNetworkConfigurationTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MGLNetworkConfigurationTests.m; sourceTree = "<group>"; };
 		CA88DC2F21C85D900059ED5A /* MGLStyleURLIntegrationTest.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = MGLStyleURLIntegrationTest.m; sourceTree = "<group>"; };
 		CA8FBC0821A47BB100D1203C /* MGLRendererConfigurationTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = MGLRendererConfigurationTests.mm; path = ../../darwin/test/MGLRendererConfigurationTests.mm; sourceTree = "<group>"; };
 		CAD9D0A922A86D6F001B25EE /* MGLResourceTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = MGLResourceTests.mm; path = ../../darwin/test/MGLResourceTests.mm; sourceTree = "<group>"; };
@@ -1554,6 +1556,7 @@
 				CA88DC2F21C85D900059ED5A /* MGLStyleURLIntegrationTest.m */,
 				077061DB215DA11F000FEF62 /* MGLTestLocationManager.h */,
 				077061D9215DA00E000FEF62 /* MGLTestLocationManager.m */,
+				CA4F3BDD230F74C3008BAFEA /* MGLMapViewPendingBlockTests.m */,
 			);
 			path = "Integration Tests";
 			sourceTree = "<group>";
@@ -3196,6 +3199,7 @@
 				CA7766842229C11A0008DE9E /* SMCalloutView.m in Sources */,
 				CA34C9C3207FD272005C1A06 /* MGLCameraTransitionTests.mm in Sources */,
 				16376B0A1FFD9DAF0000563E /* MBGLIntegrationTests.mm in Sources */,
+				CA4F3BDE230F74C3008BAFEA /* MGLMapViewPendingBlockTests.m in Sources */,
 				CA88DC3021C85D900059ED5A /* MGLStyleURLIntegrationTest.m in Sources */,
 				CA0C27942076CA19001CE5B7 /* MGLMapViewIntegrationTest.m in Sources */,
 				CA7766832229C10E0008DE9E /* MGLCompactCalloutView.m in Sources */,
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 3fc692f4e0..6d466bf2cf 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -257,6 +257,7 @@ public:
 @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;
@@ -625,6 +626,11 @@ public:
     [[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
@@ -1046,6 +1052,34 @@ public:
     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)scheduleTransitionCompletion:(dispatch_block_t)block
+{
+    // Only add a block if the display link (that calls processPendingBlocks) is
+    // running, otherwise fall back to calling immediately.
+    if (_displayLink && !_displayLink.isPaused)
+    {
+        [self willChangeValueForKey:@"pendingCompletionBlocks"];
+        [self.pendingCompletionBlocks addObject:block];
+        [self didChangeValueForKey:@"pendingCompletionBlocks"];
+        return YES;
+    }
+    
+    return NO;
+}
+
 #pragma mark - Life Cycle -
 
 - (void)updateFromDisplayLink:(CADisplayLink *)displayLink
@@ -1070,7 +1104,7 @@ public:
         return;
     }
     
-    if (_needsDisplayRefresh)
+    if (_needsDisplayRefresh || (self.pendingCompletionBlocks.count > 0))
     {
         _needsDisplayRefresh = NO;
 
@@ -1079,6 +1113,13 @@ public:
         [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();
     }
 
@@ -1145,6 +1186,7 @@ public:
     {
         [_displayLink invalidate];
         _displayLink = nil;
+        [self processPendingBlocks];
     }
 }
 
@@ -1428,6 +1470,7 @@ public:
         [MGLMapboxEvents flush];
 
         _displayLink.paused = YES;
+        [self processPendingBlocks];
 
         if ( ! self.glSnapshotView)
         {
@@ -1480,6 +1523,11 @@ public:
 {
     super.hidden = hidden;
     _displayLink.paused = hidden;
+    
+    if (hidden)
+    {
+        [self processPendingBlocks];
+    }
 }
 
 - (void)tintColorDidChange
@@ -3340,26 +3388,35 @@ public:
         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 scheduleTransitionCompletion: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;
     }
@@ -3526,12 +3583,22 @@ public:
         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 scheduleTransitionCompletion:completion])
+            {
                 completion();
-            });
+            }
+        };
+
+        animationOptions.transitionFinishFn = [pendingCompletion]() {
+            dispatch_async(dispatch_get_main_queue(), pendingCompletion);
         };
     }
 
@@ -3541,11 +3608,9 @@ public:
     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;
     }
@@ -3686,22 +3751,30 @@ public:
         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 scheduleTransitionCompletion: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;
     }
@@ -3757,22 +3830,30 @@ public:
         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 scheduleTransitionCompletion: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;
     }