[ios, macos] Refined source removal errors

Clarified and copyedited the descriptions of errors that are raised when attempting to remove a source from a style. Worded the changelog entry more generically because the same method in Swift throws an error instead of returning.

A mismatch would occur if the identifier is used by a different source than the one being removed. An application could cause this error to occur by keeping a reference to an MGLSource after changing the style URL of an MGLMapView. Another way would be to remove a source from the style, add another source to the style with the same identifier, then attempt to re-remove the original source from the style.

4 files changed, 13 insertions, 14 deletions

diff --git a/platform/darwin/resources/Base.lproj/Foundation.strings b/platform/darwin/resources/Base.lproj/Foundation.strings
index 360e3c8562..f092bdab30 100644
--- a/platform/darwin/resources/Base.lproj/Foundation.strings
+++ b/platform/darwin/resources/Base.lproj/Foundation.strings
@@ -298,9 +298,9 @@
 /* OpenStreetMap short name attribution */
 "OSM_SHORT_NAME" = "OSM";
 
-/* User-friendly error description */
-"REMOVE_SRC_FAIL_IN_USE_FMT" = "Source '%@' is in use, cannot remove.";
+/* User-friendly error description; first placeholder is the source’s identifier */
+"REMOVE_SRC_FAIL_IN_USE_FMT" = "The source “%@” can’t be removed while it is in use.";
 
 /* User-friendly error description */
-"REMOVE_SRC_FAIL_MISMATCH_FMT" = "Identifier '%1$@' does not match source identifier '%2$s'";
+"REMOVE_SRC_FAIL_MISMATCH_FMT" = "The source can’t be removed because its identifier, “%@”, belongs to a different source in this style.";
 
diff --git a/platform/darwin/src/MGLSource.mm b/platform/darwin/src/MGLSource.mm
index 62d3cfa808..fd54627471 100644
--- a/platform/darwin/src/MGLSource.mm
+++ b/platform/darwin/src/MGLSource.mm
@@ -70,20 +70,19 @@
             _pendingSource = std::move(removedSource);
             _mapView = nil;
         } else if (outError) {
-            NSString *format = NSLocalizedStringWithDefaultValue(@"REMOVE_SRC_FAIL_IN_USE_FMT", @"Foundation", nil, @"Source '%@' is in use, cannot remove.", @"User-friendly error description");
-            NSString *localizedDescription = [NSString stringWithFormat:format, self.identifier];
+            NSString *localizedDescription = [NSString stringWithFormat:
+                                              NSLocalizedStringWithDefaultValue(@"REMOVE_SRC_FAIL_IN_USE_FMT", @"Foundation", nil, @"The source “%@” can’t be removed while it is in use.", @"User-friendly error description; first placeholder is the source’s identifier"),
+                                              self.identifier];
 
             *outError = [NSError errorWithDomain:MGLErrorDomain
                                             code:MGLErrorCodeSourceIsInUseCannotRemove
                                         userInfo:@{ NSLocalizedDescriptionKey : localizedDescription }];
         }
-    }
-    else if (outError) {
-        // Consider raising an exception here
-        NSString *format = NSLocalizedStringWithDefaultValue(@"REMOVE_SRC_FAIL_MISMATCH_FMT", @"Foundation", nil, @"Identifier '%@' does not match source identifier '%s'", @"User-friendly error description");
-        NSString *localizedDescription = [NSString stringWithFormat:format,
-                                          self.identifier,
-                                          self.rawSource ? self.rawSource->getID().c_str() : "(null)"];
+    } else if (outError) {
+        // TODO: Consider raising an exception here
+        NSString *localizedDescription = [NSString stringWithFormat:
+                                          NSLocalizedStringWithDefaultValue(@"REMOVE_SRC_FAIL_MISMATCH_FMT", @"Foundation", nil, @"The source can’t be removed because its identifier, “%@”, belongs to a different source in this style.", @"User-friendly error description"),
+                                          self.identifier];
         
         *outError = [NSError errorWithDomain:MGLErrorDomain
                                         code:MGLErrorCodeSourceIdentifierMismatch
diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index 7303ae4dec..155d34a3a9 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -10,7 +10,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 ### Styles and rendering
 
 * Fixed an issue where the `{prefix}` token in tile URL templates was evaluated incorrectly when requesting a source’s tiles. ([#13429](https://github.com/mapbox/mapbox-gl-native/pull/13429))
-* Added `-[MGLStyle removeSource:error:]` that returns a `BOOL` indicating success (and an optional `NSError` in case of failure). ([#13399](https://github.com/mapbox/mapbox-gl-native/pull/13399))
+* Added an `-[MGLStyle removeSource:error:]` method that returns a descriptive error if the style fails to remove the source, whereas `-[MGLStyle removeSource:]` fails silently. ([#13399](https://github.com/mapbox/mapbox-gl-native/pull/13399))
 * Added support for setting `MGLCollisionBehaviorPre4_0` in `NSUserDefaults`. ([#13426](https://github.com/mapbox/mapbox-gl-native/pull/13426))
 * Modified the behavior of the map view so that programmatic camera transitions can no longer be interrupted by user interaction when `MGLMapView.zoomEnabled`, `MGLMapView.rotateEnabled`, `MGLMapView.scrollEnabled`, and `MGLMapView.pitchEnabled` are set to false. ([#13362](https://github.com/mapbox/mapbox-gl-native/pull/13362))
 
diff --git a/platform/macos/CHANGELOG.md b/platform/macos/CHANGELOG.md
index 2fc3935078..1692609257 100644
--- a/platform/macos/CHANGELOG.md
+++ b/platform/macos/CHANGELOG.md
@@ -4,7 +4,7 @@
 
 * `MGLMapSnapshotter` now follows "MGLIdeographicFontFamilyName" app setting to reduce font data usage while snapshotting CJK maps [#13427](https://github.com/mapbox/mapbox-gl-native/pull/13427)
 * Fixed an issue where the `{prefix}` token in tile URL templates was evaluated incorrectly when requesting a source’s tiles. ([#13429](https://github.com/mapbox/mapbox-gl-native/pull/13429))
-* Added `-[MGLStyle removeSource:error:]` that returns a `BOOL` indicating success (and an optional `NSError` in case of failure). ([#13399](https://github.com/mapbox/mapbox-gl-native/pull/13399))
+* Added an `-[MGLStyle removeSource:error:]` method that returns a descriptive error if the style fails to remove the source, whereas `-[MGLStyle removeSource:]` fails silently. ([#13399](https://github.com/mapbox/mapbox-gl-native/pull/13399))
 * Added support for setting `MGLCollisionBehaviorPre4_0` in `NSUserDefaults`. ([#13426](https://github.com/mapbox/mapbox-gl-native/pull/13426))
 * Added the `MGLFillExtrusionStyleLayer.fillExtrusionHasVerticalGradient` property. ([#13463](https://github.com/mapbox/mapbox-gl-native/pull/13463))