Convert integer to string and use each character

How is an integer converted to a string开发者_开发百科 in objective c and how is each character of the string reached?

The equivalent to the java charAt() method.

NSString *myString = [NSString stringWithFormat:@"%i", 36];
[myString characterAtIndex:0]; //"3"
[myString characterAtIndex:1]; //"6"

Update: Note that characterAtIndex returns a unichar not a c char. Thanks @Chuck.