[ios, macos] Title case attribution buttons

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

3 files changed, 73 insertions, 0 deletions

diff --git a/platform/darwin/src/NSString+MGLAdditions.h b/platform/darwin/src/NSString+MGLAdditions.h
index 45fea25588..246dc084f4 100644
--- a/platform/darwin/src/NSString+MGLAdditions.h
+++ b/platform/darwin/src/NSString+MGLAdditions.h
@@ -10,6 +10,15 @@ NS_ASSUME_NONNULL_BEGIN
 /** Returns the receiver if non-empty or nil if empty. */
 - (nullable NSString *)mgl_stringOrNilIfEmpty;
 
+/**
+ Returns a title-cased representation of the receiver using the specified
+ locale.
+ 
+ @param The locale. For strings presented to users, pass in the current locale
+    (`+[NSLocale currentLocale]`). To use the system locale, pass in `nil`.
+ */
+- (NSString *)mgl_titleCasedStringWithLocale:(NSLocale *)locale;
+
 @end
 
 @interface NSAttributedString (MGLAdditions)
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)
diff --git a/platform/darwin/test/MGLNSStringAdditionsTests.m b/platform/darwin/test/MGLNSStringAdditionsTests.m
new file mode 100644
index 0000000000..0c8a9f8143
--- /dev/null
+++ b/platform/darwin/test/MGLNSStringAdditionsTests.m
@@ -0,0 +1,42 @@
+#import <XCTest/XCTest.h>
+
+#import "NSString+MGLAdditions.h"
+
+@interface MGLNSStringAdditionsTests : XCTestCase
+
+@end
+
+@implementation MGLNSStringAdditionsTests
+
+- (void)testTitleCasedString {
+    NSLocale *locale = [NSLocale currentLocale];
+    
+    XCTAssertEqualObjects([@"© OpenStreetMap" mgl_titleCasedStringWithLocale:locale], @"© OpenStreetMap");
+    XCTAssertEqualObjects([@"© OSM" mgl_titleCasedStringWithLocale:locale], @"© OSM");
+    
+    XCTAssertEqualObjects([@"Improve this map" mgl_titleCasedStringWithLocale:locale], @"Improve This Map");
+    XCTAssertEqualObjects([@"Improve This Map" mgl_titleCasedStringWithLocale:locale], @"Improve This Map");
+    
+    XCTAssertEqualObjects([@"Improve the map" mgl_titleCasedStringWithLocale:locale], @"Improve the Map");
+    XCTAssertEqualObjects([@"Improve The Map" mgl_titleCasedStringWithLocale:locale], @"Improve The Map");
+    
+    XCTAssertEqualObjects([@"Improve a map" mgl_titleCasedStringWithLocale:locale], @"Improve a Map");
+    XCTAssertEqualObjects([@"Improve A Map" mgl_titleCasedStringWithLocale:locale], @"Improve A Map");
+    
+    XCTAssertEqualObjects([@"Improve for the map" mgl_titleCasedStringWithLocale:locale], @"Improve for the Map");
+    XCTAssertEqualObjects([@"Improve For The Map" mgl_titleCasedStringWithLocale:locale], @"Improve For The Map");
+    
+    XCTAssertEqualObjects([@"Improve and map" mgl_titleCasedStringWithLocale:locale], @"Improve and Map");
+    XCTAssertEqualObjects([@"Improve And Map" mgl_titleCasedStringWithLocale:locale], @"Improve And Map");
+    
+    XCTAssertEqualObjects([@"Improve while mapping" mgl_titleCasedStringWithLocale:locale], @"Improve While Mapping");
+    XCTAssertEqualObjects([@"Improve While Mapping" mgl_titleCasedStringWithLocale:locale], @"Improve While Mapping");
+    
+    XCTAssertEqualObjects([@"Improve with the map" mgl_titleCasedStringWithLocale:locale], @"Improve With the Map");
+    XCTAssertEqualObjects([@"Improve With The Map" mgl_titleCasedStringWithLocale:locale], @"Improve With The Map");
+    
+    XCTAssertEqualObjects([@"Improve this iPhone" mgl_titleCasedStringWithLocale:locale], @"Improve This iPhone");
+    XCTAssertEqualObjects([@"Improve This iPhone" mgl_titleCasedStringWithLocale:locale], @"Improve This iPhone");
+}
+
+@end