-[SSYUUID compactUuid] now uses character set recommended by RFC4648.

Author: jerrykrinock

SSYUuid.h

@@ -18,8 +18,19 @@
 + (NSString*)uuid ;
 
 /*!
- @brief    Returns a new UUID string represented as 22 base 64 characters
- (except with "/" replaced by "-").
+ @brief    Returns a new UUID string represented as 22 base64url characters,
+ 
+ @details  Note that base64url, defined in RFC 4648, differs from conventional
+ Base64 in that uses '-' and '_' instead of '/' and '+' as the 63rd and 64th
+ characters.  This is because these are more "URL friendly"…
+ *  https://tools.ietf.org/html/rfc4648#section-5
+ 
+ This character set has also been adopted by Mozilla for bookmark GUID in
+ Firefox:
+ *  https://bugzilla.mozilla.org/show_bug.cgi?id=607115  (Comment 2010-11-22 11:19:21 PST)
+
+ Prior to Novemeber 2016, this method used '-' and '+' as the 63rd and 64th
+ characters.
 */
  + (NSString*)compactUuid ;
 

SSYUuid.m

@@ -40,25 +40,30 @@ + (NSString*)uuid {
 }
 
  + (NSString*)compactUuid {
-	CFUUIDRef cfUUID = CFUUIDCreate(kCFAllocatorDefault) ;
-	CFUUIDBytes uuidBytes = CFUUIDGetUUIDBytes(cfUUID) ;
-    CFRelease(cfUUID) ;
-	NSData* data = [NSData dataWithBytes:(const void*)&uuidBytes
-								  length:16] ;
-	NSMutableString* s = [NSMutableString stringWithString:[data stringBase64Encoded]] ;
-
-	// Remove the padding at the end
-	[s replaceOccurrencesOfString:@"="
-					   withString:@""
-						  options:0
-							range:NSMakeRange(0, [s length])] ;
-
-	// Dashes are more readable than slashes
-	[s replaceOccurrencesOfString:@"/"
-					   withString:@"-"
-						  options:0
-							range:NSMakeRange(0, [s length])] ;
-	return [NSString stringWithString:s] ;
+     CFUUIDRef cfUUID = CFUUIDCreate(kCFAllocatorDefault) ;
+     CFUUIDBytes uuidBytes = CFUUIDGetUUIDBytes(cfUUID) ;
+     CFRelease(cfUUID) ;
+     NSData* data = [NSData dataWithBytes:(const void*)&uuidBytes
+                                   length:16] ;
+     NSMutableString* s = [NSMutableString stringWithString:[data stringBase64Encoded]] ;
+     
+     // Remove the padding at the end
+     [s replaceOccurrencesOfString:@"="
+                        withString:@""
+                           options:0
+                             range:NSMakeRange(0, [s length])] ;
+     
+     // Change from standard Base64 to base64url (RFC4648) character set
+     [s replaceOccurrencesOfString:@"/"
+                        withString:@"-"
+                           options:0
+                             range:NSMakeRange(0, [s length])] ;
+     [s replaceOccurrencesOfString:@"+"
+                        withString:@"_"
+                           options:0
+                             range:NSMakeRange(0, [s length])] ;
+     
+     return [NSString stringWithString:s] ;
 }
 
 @end