[macos] Make + and - keys zoom the map

Override `insertText:`

- send all `keyDown:` events to `interpretKeyEvents:` method;
- in `insertText:` method check for the text to be sent and
  adjust zoom level if needed;

platform/macos/CHANGELOG.md

@@ -41,6 +41,7 @@
 * Added a method to MGLMapViewDelegate, `-mapView:shouldChangeFromCamera:toCamera:`, that you can implement to restrict which parts the user can navigate to using gestures. ([#5584](https://github.com/mapbox/mapbox-gl-native/pull/5584))
 * Added a `MGLDistanceFormatter` class for formatting geographic distances. ([#7888](https://github.com/mapbox/mapbox-gl-native/pull/7888))
 * Zooming by double-tap, two-finger tap, zoom buttons, shortcut keys, or demo app menu items or shortcut keys now zooms to the nearest integer zoom level. ([#8027](https://github.com/mapbox/mapbox-gl-native/pull/8027))
+* Make "+" and "-" keys zoom in and out ([8033](https://github.com/mapbox/mapbox-gl-native/pull/8033))
 
 ## 0.3.1
 

platform/macos/src/MGLMapView.mm

@@ -1633,13 +1633,16 @@ public:
 #pragma mark Keyboard events
 
 - (void)keyDown:(NSEvent *)event {
-    if (event.modifierFlags & NSNumericPadKeyMask) {
-        // This is the recommended way to handle arrow key presses, causing
-        // methods like -moveUp: and -moveToBeginningOfParagraph: to be called
-        // for various standard keybindings.
-        [self interpretKeyEvents:@[event]];
+    [self interpretKeyEvents:@[event]];
+}
+
+- (void)insertText:(NSString *)text {
+    BOOL textIsZoomCharacter = [@[@"-", @"=", @"+"] containsObject:text];
+
+    if (textIsZoomCharacter) {
+        [self adjustZoomLevelForKey:text];
     } else {
-        [super keyDown:event];
+        [super insertText:text];
     }
 }
 
@@ -1695,6 +1698,23 @@ public:
     _compass.hidden = !rotateEnabled;
 }
 
+- (void)adjustZoomLevelForKey:(NSString *)key {
+    double newZoomLevel = self.zoomLevel;
+    unichar keyUnichar = [key characterAtIndex:0];
+    switch(keyUnichar) {
+        case '-': {
+            newZoomLevel -= 1;
+            break;
+        }
+        case '=':
+        case '+': {
+            newZoomLevel += 1;
+        }
+    }
+
+    [self setZoomLevel:newZoomLevel animated:YES];
+}
+
 #pragma mark Ornaments
 
 /// Updates the zoom controls’ enabled state based on the current zoom level.