Check if string contains only alphabets. Using NSString, NSCharacterSet, NSRange.

+(BOOL) validateStringContainsAlphabetsOnly:(NSString*)strng

{

    NSCharacterSet *strCharSet = [NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"];//1234567890_"];

    strCharSet = [strCharSet invertedSet];

    //And you can then use a string method to find if your string contains anything in the inverted set:

        NSRange r = [strng rangeOfCharacterFromSet:strCharSet];

    if (r.location != NSNotFound) {

        NSLog(@"the string contains illegal characters");

        return NO;

    }

    else

        return YES;

}