Naviagtion Controller和Tab Bar Controller问题

有两种方法。
1.

-(void) viewWillDisappear:(BOOL)animated {
    if ([self.navigationController.viewControllers indexOfObject:self]==NSNotFound) {
       //在这里加上 alertview 
      [self.navigationController popViewControllerAnimated:NO];
    }
    [super viewWillDisappear:animated];
}
2.创建一个自定义的 button

- (void)viewDidLoad {
    [super viewDidLoad];
    UIBarButtonItem *newBackButton = [[UIBarButtonItem alloc] initWithTitle:@"Home" style:UIBarButtonItemStyleBordered target:self action:@selector(home:)];
    self.navigationItem.leftBarButtonItem=newBackButton;
}

-(void)home:(UIBarButtonItem *)sender {
        //在这里增加一个 alertview 
       //在 alertview 的回调方法中写上 [self.navigationController popToRootViewControllerAnimated:YES]; 就可以返回了
}