The NSString class provides a lot of useful methods, one of these gives you the capability to extract the first n characters from an NSString
imagine you have the following NSString
NSString *originalString=@"My NSString";
to extract the first two characters, simply type the following line:
NSstring *firstTwoCharsString= [originalString substringToIndex:2];
at this point firstTwoCharsString contains "My".
You can obtain the last n characters of a string simply typing the following line of code:
NSstring *lastTwoCharsString= [originalString substringFromIndex:[originalString length]-2];
That's all,
Gg1.