use textView inputAccessoryView

gistfile1.m

- (void)awakeFromNib
{
    // Initialization code
    self.textView.delegate = self;
    
    UIToolbar *tipToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 50)];
    tipToolbar.barStyle = UIBarStyleBlackOpaque;
    tipToolbar.items = [NSArray arrayWithObjects:

                        [[UIBarButtonItem alloc] initWithTitle:@"Calculate"
                                                         style:UIBarButtonItemStyleBordered
                                                        target:nil
                                                        action:nil],

                        [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
                                                                      target:nil
                                                                      action:nil],

                        [[UIBarButtonItem alloc] initWithTitle:@"Done"
                                                         style:UIBarButtonItemStyleBordered
                                                        target:nil
                                                        action:nil],
                        nil];
    [tipToolbar sizeToFit];
    self.textView.inputAccessoryView = tipToolbar;
}