insert a string using UIKeyInput methods in UITextView in iOS5

insertString.m

- (void)insertString:(NSString *)inputKey
{
  // Insert text (doing delegate calls appropiately)
  NSRange changeRange = target.selectedRange;
  if (!target.delegate || ([target.delegate respondsToSelector:@selector(textView:shouldChangeTextInRange:replacementText:)] &&
                           [target.delegate textView:target shouldChangeTextInRange:changeRange replacementText:inputKey])) {
    // MarkedText could happen in multi-stage input languages
    // In iOS5 several methods of UITextInput and UIKeyInput are badly implemented in UITextView
    // setMarkedText:selectedRange: method seems to delete current markedText. 
    // Unmarking the text before inserting it is better than nothing.
    
    UITextRange *markedTextRange = [target markedTextRange];
    if (markedTextRange) {
      if ([[[UIDevice currentDevice] systemVersion] hasPrefix:@"5."]) {
        // In iOS5 setMarkedText:selectedRange: is buggy and pretty useless in iOS5
        // http://stackoverflow.com/questions/8066628/uitextinput-setmarkedtextselectedrange-not-working-cant-be
        // rdar://10867047
        [target unmarkText];
        [target insertText:inputKey];
      } else {
        // According to Apple, rdar://10867047 is solved in iOS6b1
        // Yeah setMarkedText:selectedRange: itself works but it brakes current
        // multi-stage input session. In other words it still useless.
        // Ideally below code would work but it doesn't :(
        NSMutableString *markedText = [[target textInRange:markedTextRange] mutableCopy];
        NSInteger markedTextStart = [target offsetFromPosition:target.beginningOfDocument toPosition:markedTextRange.start];
        NSRange curSelection = [target selectedRange];
        NSInteger loc = curSelection.location - markedTextStart;

        [markedText insertString:inputKey atIndex:loc];
        [target setMarkedText:markedText selectedRange:NSMakeRange(loc + inputKey.length, 0)];
        [markedText release];
      }
    } else {
      [target insertText:inputKey];
    }

    [[UIDevice currentDevice] playInputClick];

    if ([target.delegate respondsToSelector:@selector(textViewDidChange:)]) {
      [target.delegate textViewDidChange:target];
    }
    // Do not call textViewDidChangeSelection:, it is not called through text insertion/deletion
  }
}