- (void)addButtonToKeyboardWithSelector:(SEL)sel normal:(UIImage*)nimg highlight:(UIImage*)himg{

    // create custom button

    UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeCustom];

    doneButton.tag=8;

    doneButton.frame = CGRectMake(0, 0, 106, 53);

    doneButton.adjustsImageWhenHighlighted = NO;

    

    [doneButton setImage:nimg forState:UIControlStateNormal];

    [doneButton setImage:himg forState:UIControlStateHighlighted];

    [doneButton addTarget:self action:sel forControlEvents:UIControlEventTouchUpInside];

    // locate keyboard view

   //这样更合理一点

    int cnt=[[UIApplication sharedApplication] windows].count;

    UIWindow* keyboardWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:cnt-1];

    doneButton.frame = CGRectMake(0, keyboardWindow.frame.size.height-53, 106, 53);

    if([[keyboardWindow description] hasPrefix:@"
        [keyboardWindow addSubview:doneButton];

    

    NSLog(@"keyboard:%@ %@ %@",NSStringFromCGRect(keyboardWindow.frame),NSStringFromCGRect(doneButton.frame),keyboardWindow.subviews);

}



- (void)removeButtonFromKeyboard {

    // locate keyboard view

    for (NSUInteger i=0; i<[[UIApplication sharedApplication] windows].count; i++) {

        UIWindow* tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:i];

        if([[tempWindow description] hasPrefix:@"
            [[tempWindow viewWithTag:8] removeFromSuperview];

        }

    }

}