[ios, macos] Default to local rendering of CJK characters, using system font (#14862)

* Change default CJK font from "PingFang" to "Helvetica"

* Add CHANGELOG.

* Update CHANGELOG.

* [ios] Enable client-side rendering and use `Helvetica` by default. Set `MGLIdeographicFontFamilyName` to `NULL` for using your custom remote font.

* [ios] Update change log

* [ios] Change default CJK configuration in `iosapp` project

* [ios] Update comment

* [ios] return local font name using default system font.

* [ios] Update changelog

* [ios] update changelogs & comments

* [iOS, macOS]Support mac os

* [iOS, macOS] fix bug

* [iOS, macOS] update change log

* [iOS, macOS] fix nit.

* [iOS, macOS] Ability to specify an array of fonts for fallbacks for `localIdeographicFontFamily`

* [iOS, macOS] Update comments

* [iOS, macOS] Update change log

* [iOS, macOS] update for mac OS font family names

* Fix nit.

* Update platform/ios/CHANGELOG.md

Co-Authored-By: Minh Nguyễn <mxn@1ec5.org>

* [iOS, macOS] Set `MGLIdeographicFontFamilyName` to a Boolean value `NO` for using your custom remote font.

* [iOS, macOS] remove `MGLIdeographicFontFamilyName` from info.plist & update Info.plist Keys.md

* [iOS, macOS] remove `MGLIdeographicFontFamilyName` from macOS demo app project and update info.plist Keys.md

* [iOS, macOS] update macOS changelog

* [iOS, macOS] Change docs

* Update Change log

* [iOS, macOS] Test case

* Update platform/macos/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/macos/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/ios/CHANGELOG.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/darwin/src/MGLRendererConfiguration.mm

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/darwin/test/MGLRendererConfigurationTests.mm

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/macos/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/macos/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/macos/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* [iOS, macOS] update comments

* [iOS, macOS] add plist value test && filter for invalid string

* [iOS, macOS] fix nit

* Update platform/ios/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/ios/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/ios/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/macos/CHANGELOG.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/ios/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* Update platform/ios/docs/guides/Info.plist Keys.md

Co-Authored-By: Jason Wray <friedbunny@users.noreply.github.com>

* [iOS, macOS] add invalid value type test

* Apply own suggestions from code review

2 files changed, 63 insertions, 11 deletions

diff --git a/platform/darwin/src/MGLRendererConfiguration.h b/platform/darwin/src/MGLRendererConfiguration.h
index ee5aaef174..bfe88b7209 100644
--- a/platform/darwin/src/MGLRendererConfiguration.h
+++ b/platform/darwin/src/MGLRendererConfiguration.h
@@ -23,14 +23,21 @@ MGL_EXPORT
 /** The cache dir to use. */
 @property (nonatomic, readonly) mbgl::optional<std::string> cacheDir;
 
-/** The name of the font family to use for client-side text rendering.
-
- Currently only used for CJK glyphs. Changing this at run time is not currently
- supported. Enable client-side rendering of CJK glyphs by setting
- `MGLIdeographicFontFamilyName` in your containing app's Info.plist to a value
- which will be available at run time. Default font for local ideograph font family
- is "PingFang". */
-@property (nonatomic, readonly) std::string localFontFamilyName;
+/** The name of the font family to use for client-side text rendering of CJK ideographs.
+ 
+ Set MGLIdeographicFontFamilyName in your containing application's Info.plist to
+ font family name(s) that will be available at run time, such as “PingFang TC”
+ or “Marker Felt”. This plist key accepts:
+ 
+ - A string value of a single font family name.
+ 
+ - An array of font family names. Fonts will be used in the defined order,
+ eventually falling back to default system font if none are available.
+ 
+ - A boolean value NO to disable client-side rendering of CJK glyphs —
+ remote fonts specified in your style will be used instead.
+ */
+@property (nonatomic, readonly) mbgl::optional<std::string> localFontFamilyName;
 
 /**
  A Boolean value indicating whether symbol layers may enable per-source symbol
diff --git a/platform/darwin/src/MGLRendererConfiguration.mm b/platform/darwin/src/MGLRendererConfiguration.mm
index d616e93eb2..54bdcaa691 100644
--- a/platform/darwin/src/MGLRendererConfiguration.mm
+++ b/platform/darwin/src/MGLRendererConfiguration.mm
@@ -9,6 +9,7 @@
 #endif
 
 static NSString * const MGLCollisionBehaviorPre4_0Key = @"MGLCollisionBehaviorPre4_0";
+static NSString * const MGLIdeographicFontFamilyNameKey = @"MGLIdeographicFontFamilyName";
 
 @interface MGLRendererConfiguration ()
 @property (nonatomic, readwrite) BOOL perSourceCollisions;
@@ -69,10 +70,54 @@ static NSString * const MGLCollisionBehaviorPre4_0Key = @"MGLCollisionBehaviorPr
     return mbgl::optional<std::string>();
 }
 
-- (std::string)localFontFamilyName {
-    NSString *fontFamilyName = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"MGLIdeographicFontFamilyName"];
+- (mbgl::optional<std::string>)localFontFamilyName {
+    return [self _localFontFamilyNameWithPropertyDictionary:[[NSBundle mainBundle] infoDictionary]];
+}
 
-    return fontFamilyName ? std::string([fontFamilyName UTF8String]) : std::string("PingFang");
+- (mbgl::optional<std::string>)_localFontFamilyNameWithPropertyDictionary:(nonnull NSDictionary *)properties {
+    
+    std::string systemFontFamilyName;
+#if TARGET_OS_IPHONE
+    systemFontFamilyName = std::string([[UIFont systemFontOfSize:0 weight:UIFontWeightRegular].familyName UTF8String]);
+#else
+    systemFontFamilyName = std::string([[NSFont systemFontOfSize:0 weight:NSFontWeightRegular].familyName UTF8String]);
+#endif
+    
+    id fontFamilyName = properties[MGLIdeographicFontFamilyNameKey];
+    
+    if([fontFamilyName isKindOfClass:[NSNumber class]] && ![fontFamilyName boolValue])
+    {
+        return mbgl::optional<std::string>();
+    }
+    else if([fontFamilyName isKindOfClass:[NSString class]])
+    {
+        BOOL isValidFont = NO;
+#if TARGET_OS_IPHONE
+        if([[UIFont familyNames] containsObject:fontFamilyName]){
+            isValidFont = YES;
+        }
+#else
+        if([[[NSFontManager sharedFontManager] availableFontFamilies] containsObject:fontFamilyName]){
+            isValidFont = YES;
+        }
+#endif
+        return (fontFamilyName && isValidFont) ? std::string([fontFamilyName UTF8String]) : systemFontFamilyName;
+    }
+    // Ability to specify an array of fonts for fallbacks for `localIdeographicFontFamily`
+    else if ([fontFamilyName isKindOfClass:[NSArray class]]){
+        for(NSString *name in fontFamilyName){
+#if TARGET_OS_IPHONE
+            if([[UIFont familyNames] containsObject:name]){
+                return std::string([name UTF8String]);
+            }
+#else
+            if([[[NSFontManager sharedFontManager] availableFontFamilies] containsObject:name]){
+                return std::string([name UTF8String]);
+            }
+#endif
+        }
+    }
+    return systemFontFamilyName;
 }
 
 @end