Emoji in UILabel

Question

Ive been trying to find a solution to my problem all day with no success. I know its probably something silly since I am still new to OBjective C so heres my issue.

I'm trying to implement unicode Emoji Characters into a UILabel. So lets take it one step at a time.

Here is the Json String I am using:

"body":"\\U0001f61f \\U0001f62e \\U0001f621"

As you can see the Json Serializer im using escapes the unicode. I suspect this is my main problem.

I am retrieving the data like so:

  dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{

    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    NSString *concat=[NSString stringWithFormat:@"MYURL?ID=%@",_TID];
    NSURL *url = [NSURL URLWithString:concat];
    NSData *jsonData=[NSData dataWithContentsOfURL:url];

    dispatch_async(dispatch_get_main_queue(), ^{
        if (jsonData!=nil) {
            newX= [[NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableLeaves error:nil]mutableCopy];
            pageCounter=2;
            [self.topicView reloadData];
            [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;            }
        [loadingView
         performSelector:@selector(removeView)
         withObject:nil
         afterDelay:1];
    });
});

After some time later the data is called and added to the UILabel.

UILabel *emo=(UILabel*)[Tcell viewWithTag:6];
   NSString*body=[[[newX objectAtIndex:indexPath.row] valueForKey:@"body"] mutableCopy];
   emo.text=body;

Which just gives me \U0001f61f \U0001f62e \U0001f621 as text. I know its probably just an encoding issue but I have no idea where to attack this.

Any help would be appreciated. :)

Answer 1

When your json string is "\U0001f61f" json understands \\ as an escape to represent a literal slash. You should only use a single slash if you want the "U" and hexadecimal digits themselves to be escaped.

---

When you create a string like this:

NSString *s = @"\U0001f61f \U0001f62e \U0001f621";

You get emoji characters because the Objective-C compiler understands and transforms the \U escapes (called Universal Character Names, from C and C++) to the appropriate characters in string literals. If you use a string from json, or a plist, or anything other than a string literal the escape sequence will not be processed at compile time by the Objective-C compiler.

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Note: See the C or C++ language specifications to see how escapes in string literals are processed in Objective-C or Objective-C++.

---

Instead you want to create a string in json using escapes json understands. Unfortunately json is deficient in its Unicode support for characters outside the BMP (i.e., greater than U+FFFF). json has a \u escape, but it only supports four hexadecimal digits. To use this with characters outside the BMP there's a hack that involves using surrogate codepoints just as UTF-16 does.

The json string that encodes the characters you want is:

"body":"\uD83D\uDE1F \uD83D\uDE2E \uD83D\uDE21"

(If you use Google to search for a Unicode character using the format U+123456 it will find a page that tells you the UTF-16 encoding.)

Hopefully this is the only change you need to make, however I'm unsure if NSJSONSerialization supports this hack. If this doesn't work on its own you'll need to take a look at the documentation (assuming the behavior is documented) for how NSJSONSerialization produces string data from json data.

Answer 2

I use the below code to encode emoji character

NSString *uniText = [NSString stringWithUTF8String:[textview.text UTF8String]]; NSData *msgData = [uniText dataUsingEncoding:NSNonLossyASCIIStringEncoding]; NSString *goodMsg = [[NSString alloc] initWithData:msgData encoding:NSUTF8StringEncoding] ;

And the below code to decode and display in UILabel

const char *jsonString = [body UTF8String]; NSData *jsonData = [NSData dataWithBytes:jsonString length:strlen(jsonString)]; NSString *goodMsg = [[NSString alloc] initWithData:jsonData encoding:NSNonLossyASCIIStringEncoding];

Answer 3

To display those characters you need to use a font in which they are valid. On iOS that means using the Apple Color Emoji font.

Answer 4

So after spending all day doing this the ONLY solution I found was to create an NSMutableDictionary and call the keys from there.