嵌入为子视图控制器时，UINavigationController的高度为零

Question

我有一个应用，其中包含孩子UIView的{​​{1}}从底部向上滑动。 子控制器通过自动布局来定义高度。

这是我的工作代码：

UIViewController

现在，我想在动画之前将现有的子控制器嵌入// controller is new added controller addChildViewController(controller) controller.view.translatesAutoresizingMaskIntoConstraints = false bottomSheetViewContainerView.translatesAutoresizingMaskIntoConstraints = false bottomSheetViewContainerView.addSubview(controller.view) // Setting only top, left, right anchors so the view isn't squished on sliding up controller.view.leftAnchor.constraint(equalTo: bottomSheetViewContainerView.leftAnchor).isActive = true controller.view.rightAnchor.constraint(equalTo: bottomSheetViewContainerView.rightAnchor).isActive = true controller.view.topAnchor.constraint(equalTo: bottomSheetViewContainerView.topAnchor).isActive = true // This calculates the correct height bottomSheetViewContainerView.layoutIfNeeded() print("controller.view.bounds.height: \(controller.view.bounds.height)") bottomSheetViewContainerView.heightAnchor.constraint(equalToConstant: controller.view.bounds.height).isActive = true // bottomSheetContainerView slides up UIView.animate(withDuration: 0.40) { self.view.layoutIfNeeded() } 中。但是当我这样做时，高度为零。不知何故，它没有达到顶部ViewController的高度...

UINavigationController的高度也为零。如何强制计算其高度？

Answer 1

///仅设置顶部，左侧，右侧锚点，以使视图在向上滑动时不会被压缩

controller.view.leftAnchor.constraint(equalTo: bottomSheetViewContainerView.leftAnchor).isActive = true
controller.view.rightAnchor.constraint(equalTo: bottomSheetViewContainerView.rightAnchor).isActive = true
controller.view.topAnchor.constraint(equalTo: bottomSheetViewContainerView.topAnchor).isActive = true

您应该添加底部> = 0约束

然后删除

bottomSheetViewContainerView.heightAnchor.constraint(equalToConstant: controller.view.bounds.height).isActive = true

如果控制器视图中的约束正确无误，那么它应该起作用。