How to deal with my code?

Question

Objective-C

You need to write code to convert from decimal to hexadecimal.
There is a code written in the appcode.
I've been suffering with it for the 3rd day and I can't figure out what's wrong? Help me please.
NSString * dechex(int ​​value)
{
int base = 16;
int initialResult = value;
int initialResultTake = value;
int secondaryOutcome = 0;
NSString *string = @"";
for (int i = 0; initialResult > i; i++)
{
initialResult = initialResult / basa;
secondaryOutcome = initialResultTake % base;
initialResultTake = initialResult;
switch (secondaryOutcome)
{
case 10:
{
string = @"A";
break;
}
case 11:
{
string = @"B";
break;
}
case 12:
{
string = @"C";
break;
}
case 13:
{
string = @"D";
break;
}
case 14:
{
string = @"E";
break;
}
case 15:
{
string = @"F";
break;
}
default:
{
string = [NSString stringWithFormat:@"%i", secondaryOutcome];
break;
}
}
NSLog(@"%@", string);
}
return string;
}
int main(int argc, char *argv[])
{
dechex(12021);
return 0;
}

Answer 1

NSString * dechex(int value)
{
    const NSString* chars = @"0123456789ABCDEF";
    size_t base = chars.length;
    NSString* result = @"";
    while (value >= base) {
        result = [NSString stringWithFormat:@"%@%@",[chars substringWithRange:NSMakeRange(value % base,1)], result];
        value = value / base;
    }
    result = [NSString stringWithFormat:@"%@%@",[chars substringWithRange:NSMakeRange(value,1)], result];
    NSLog(@"%@", result);
    return result;
}

Answer 2

NSString * hexFromDex(int a)
{
  return [NSString stringWithFormat:@"%X", a];
}