Question

I am making an app that posts content from a UITextField, to a PHP script, and store in a database to read later. I am having one heck of a time working with emojis.

Using json, I will get a response like this:

content = "\Uf44d";
id = 104;
time = 1350359055;

In this instance, I used an emoji. But when I do [dictionary objectForKey:@"content"], a box just appears. 

I’m thinking I need to convert to UTF-8. But I’m not completely sure. Please help!

Answer 1

U+F44D is a Unicode character in the “Private Use Area” U+E000..U+F8FF, so that is probably not the character you want to display.

On the other hand, U+1F44D is the “THUMBS UP SIGN”, so it could be that your Web service does not create a correct JSON response for Unicode characters greater than 0xFFFF.

According to the JSON RFC, characters that are not part of the “Basic Multilingual Plane” can be escaped using a UTF-16 surrogate pair. For the U+1F44D character the JSON Unicode escape sequence would be “\ud83d\udc4d”.

The following code shows that it works in general:

const char *s = "{ \"content\": \"\\ud83d\\udc4d\", \"id\": 104, \"time\": 1350359055 }";
NSData *jsonData = [NSData dataWithBytes:s length:strlen(s)];
NSError *error;
NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error];
self.label.text = [jsonDict objectForKey:@"content"];

This displays the “THUMBS UP SIGN” correctly in the label.

But you don’t have to escape characters, the Web service could also just send the UTF-8 sequence.