容器视图中的 UI 未更新

Question

我有一个带有按钮的视图，当用户按下按钮时，会显示一个容器视图。我用：

ContainerView.setNeedsDisplay()

更新容器视图。我这样做是因为我有诸如标签之类的 UI，并且我希望文本基于单击的按钮。

问题在于，在更新视图和更新文本时，标签文本不会改变。

Answer 1

感谢 Rroobb 的评论，这很有效！ - stackoverflow.com/a/37748737/3108877

Answer 2

我写了一个助手来做这个，源代码可以帮助你：

+ (void)navigateFromController:(UIViewController *)fromController toController:(UIViewController *)toController {
    if (fromController) {
        // Remove any existing child controllers.
        for (UIViewController *child in [toController childViewControllers]) {
            [child willMoveToParentViewController:nil];
            [child.view removeFromSuperview];
            [child removeFromParentViewController];
        }

        // Embed the new controller.
        [fromController addChildViewController:toController];

        toController.view.frame = fromController.view.bounds;
        toController.view.translatesAutoresizingMaskIntoConstraints = false;
        [fromController.view addSubview:toController.view];

        [toController.view.leftAnchor constraintEqualToAnchor:fromController.view.leftAnchor].active = YES;
        [toController.view.rightAnchor constraintEqualToAnchor:fromController.view.rightAnchor].active = YES;
        [toController.view.topAnchor constraintEqualToAnchor:fromController.view.topAnchor].active = YES;
        [toController.view.bottomAnchor constraintEqualToAnchor:fromController.view.bottomAnchor].active = YES;

        [fromController didMoveToParentViewController:fromController];
    }
}