converting strings containing \u#### to characters on iOS iPhone - iphone

Question

I receive a JSON response in a NSData Variable, and then convert the NSDATA into NSString:
NSString *aStr = [[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding];
The problem is this string now contains character sequences of teh format \u####.
(for example, Joe\u2019s).
I want to convert all such occurrences with their single character representation. (for example Joe\u2019s should become Joe's.
Any ideas on how to do this?
Also, could someone point me to a resource where i can learn the right terminology for this?
Thanks a lot!

Answer 1

I looked for a answer to this question for far too long today... finally just bit the bullet and wrote my own category on NSString. Feel free to correct mistakes, I'm not a unicode wizard. This definitely doesn't handle unicode past \uffff but I don't need that in my situation.
#interface NSString (UnicodeAdditions)
-(NSString *) unescapeUnicode;
#end
#implementation NSString (UnicodeAdditions)
-(NSString *) unescapeUnicode {
NSString *input = self;
int x = 0;
NSMutableString *mStr = [NSMutableString string];
do {
unichar c = [input characterAtIndex:x];
if( c == '\\' ) {
unichar c_next = [input characterAtIndex:x+1];
if( c_next == 'u' ) {
unichar accum = 0x0;
int z;
for( z=0; z<4; z++ ) {
unichar thisChar = [input characterAtIndex:x+(2+z)];
int val = 0;
if( thisChar >= 0x30 && thisChar <= 0x39 ) { // 0-9
val = thisChar - 0x30;
}
else if( thisChar >= 0x41 && thisChar <= 0x46 ) { // A-F
val = thisChar - 0x41 + 10;
}
else if( thisChar >= 0x61 && thisChar <= 0x66 ) { // a-f
val = thisChar - 0x61 + 10;
}
if( z ) {
accum <<= 4;
}
accum |= val;
}
NSString *unicode = [NSString stringWithCharacters:&accum length:1];
[mStr appendString:unicode];
x+=6;
}
else {
[mStr appendFormat:#"%c", c];
x++;
}
}
else {
[mStr appendFormat:#"%c", c];
x++;
}
} while( x < [input length] );
return( mStr );
}
#end