Question

当我将子视图控制器添加到表视图单元格时，看起来没有调用子视图控制器的 viewWillAppear ，只有 viewDidAppear 。

表视图控制器方法：

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
    let cell = tableView.dequeueReusableCellWithIdentifier("ShopInfoTableViewCell", forIndexPath: indexPath) as! ShopInfoTableViewCell
    self.addChildViewController(self.shopInfoViewController, toView: cell.containerView)
    return cell
}

查看控制器类别方法：

- (void)addChildViewController:(UIViewController *)childController toView:(UIView *)view
{
    [self addChildViewController:childController];
    [view addSubview:childController.view];
    [childController didMoveToParentViewController:self];

    [childController.view mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(view.mas_top);
        make.bottom.equalTo(view.mas_bottom);
        make.left.equalTo(view.mas_left);
        make.right.equalTo(view.mas_right);
    }];
}

任何想法为什么会发生？

Answer 1

- (void)addChildViewController:(UIViewController *)childController toView:(UIView *)view
{
    [self addChildViewController:childController];

    //add this
    [childController beginAppearanceTransition:YES animated:YES];
    [view addSubview:childController.view];
    [childController endAppearanceTransition];

    [childController didMoveToParentViewController:self];

    [childController.view mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(view.mas_top);
        make.bottom.equalTo(view.mas_bottom);
        make.left.equalTo(view.mas_left);
        make.right.equalTo(view.mas_right);
    }];
}

同样，当你想要消失时，你应该调用它

    [childController beginAppearanceTransition:NO animated:YES];
    [childController.view removeFromSuperview];
    [childController endAppearanceTransition];

Answer 2

要@adali回答我会改变：

[childController beginAppearanceTransition:YES animated:YES];

由：

[childController willMoveToParentViewController:self];

所以最后会是：

[self addChildViewController:childController]; //add the child on childViewControllers array
[childController willMoveToParentViewController:self]; //viewWillAppear on childViewController
[self.containerView addSubview:childController.view]; //add childView whenever you want
[childController didMoveToParentViewController:self]; //viewDidAppear on childViewController

非常重要，一旦包含子项的viewController已经执行了viewWillAppear life cicle函数，就必须调用所有这些

将子控制器添加到表视图单元时，不会调用viewWillAppear

2 个答案: