iOS聊天界面底部黑色边框的问题

在聊天页面中加入如下代码：（隐藏tabbar，并且将bounds设置为0）
- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    
    self.tabBarController.tabBar.hidden = YES;
    
    self.tabBarController.tabBar.bounds = CGRectMake(0, 0, 0, 0);

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    
    self.tabBarController.tabBar.hidden = NO;
    
    self.tabBarController.tabBar.bounds = CGRectMake(0, self.view.frame.origin.y - 64, self.view.frame.size.width, 44);