在键盘上添加UIToolBar，隐藏键盘

- (void) addToolBarlOnKeyboard {
    
    //在键盘上添加toolbar工具条  点击工具条中的按钮回收键盘
    UIToolbar * toolBar = [[UIToolbar alloc]initWithFrame:CGRectMake(0, 0, 320, 30)];
    [toolBar setBarStyle:UIBarStyleDefault];
    UIBarButtonItem * btnSpace = [[UIBarButtonItem  alloc]initWithBarButtonSystemItem:                                        UIBarButtonSystemItemFlexibleSpace target:self action:nil];
    UIBarButtonItem * doneButton = [[UIBarButtonItem alloc]initWithTitle:@"隐藏键盘"            style:UIBarButtonItemStyleDone  target:self action:@selector(takebackkeyboard)];
    NSArray * buttonsArray = [NSArray arrayWithObjects:btnSpace,doneButton,nil];
    //关键的代码，不写的话不会在键盘上面显示工具条
    [_commentView setInputAccessoryView:toolBar];
    
    [toolBar setItems:buttonsArray];
    [toolBar release];
    [btnSpace release];
    [doneButton release];
    
}

- (void)takebackkeyboard {
    [_commentView resignFirstResponder];    
}