[ios, macos] Title case attribution buttons

Also added a category method on NSString for title casing the string, plus tests.

1 files changed, 22 insertions, 0 deletions

diff --git a/platform/darwin/src/NSString+MGLAdditions.m b/platform/darwin/src/NSString+MGLAdditions.m
index 04a65dc5e2..5c32f4b789 100644
--- a/platform/darwin/src/NSString+MGLAdditions.m
+++ b/platform/darwin/src/NSString+MGLAdditions.m
@@ -10,6 +10,28 @@
     return self.length ? self : nil;
 }
 
+- (NSString *)mgl_titleCasedStringWithLocale:(NSLocale *)locale {
+    NSMutableString *string = self.mutableCopy;
+    [string enumerateLinguisticTagsInRange:string.mgl_wholeRange scheme:NSLinguisticTagSchemeLexicalClass options:0 orthography:nil usingBlock:^(NSString * _Nonnull tag, NSRange tokenRange, NSRange sentenceRange, BOOL * _Nonnull stop) {
+        NSString *word = [string substringWithRange:tokenRange];
+        if (word.length > 3
+            || !([tag isEqualToString:NSLinguisticTagConjunction]
+                 || [tag isEqualToString:NSLinguisticTagPreposition]
+                 || [tag isEqualToString:NSLinguisticTagDeterminer]
+                 || [tag isEqualToString:NSLinguisticTagParticle]
+                 || [tag isEqualToString:NSLinguisticTagClassifier])) {
+            unichar firstLetter = [[word capitalizedStringWithLocale:locale] characterAtIndex:0];
+            NSString *suffix = [word substringFromIndex:1];
+            if (!([word hasPrefix:@"i"] && suffix.length
+                  && [[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[suffix characterAtIndex:0]])) {
+                word = [NSString stringWithFormat:@"%C%@", firstLetter, suffix];
+            }
+        }
+        [string replaceCharactersInRange:tokenRange withString:word];
+    }];
+    return string;
+}
+
 @end
 
 @implementation NSAttributedString (MGLAdditions)