One Quickie

---

Appending to the end of a textview (NSTextView->General)

    NSRange range;
    range = NSMakeRange ([[textView string] length], 0);

    [textView replaceCharactersInRange: range withString: string];

And Peter Hosey provided a one-liner that may suit your needs better:

    [[[textView textStorage] mutableString] appendString: string];