libb64-iOS is a lightweight objective-c wrapper around libb64 for easy base 64 encoding and decoding on iOS.
It is implemented as a category on NSData with two methods:
-(NSString*)stringByBase64Encoding - creates an NSString by base64 encoding the data stored in the NSData object.
+(NSData*)dataByBase64DecodingString:(NSString*)base64String - creates an NSData by base64 decoding the data stored in base64String.