以編程方式添加沒有故事板的容器視圖？

Question

我在viewDidLoad有這個：

    let childViewControllerForPosts = PostsCollectionViewController(collectionViewLayout: UICollectionViewLayout())
    let cView = childViewControllerForPosts.view
    self.view.backgroundColor = UIColor.redColor()
    self.addChildViewController(childViewControllerForPosts)
    self.view.addSubview(cView)
    childViewControllerForPosts.didMoveToParentViewController(self)

    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(handleScroll(_:)), name: "cvScrolled", object: nil)

    cView.widthAnchor.constraintEqualToConstant(view.frame.size.width).active = true
    cView.heightAnchor.constraintEqualToConstant(view.frame.size.height).active = true
    cView.topAnchor.constraintEqualToAnchor(containerForGreyAndPurple.bottomAnchor).active = true
    cView.centerXAnchor.constraintEqualToAnchor(view.centerXAnchor).active = true

但是，我收到一條錯誤消息，說這是非法約束，因為它沒有共同的祖先:(

這是錯誤：

...because they have no common ancestor. Does the constraint reference items in different view hierarchies? That's illegal.'

Answer 1

您沒有正確設置約束。

您首先需要使用父視圖和容器視圖添加約束，然后還需要向容器控制器添加約束。 最后，您應該在設置所有約束的末尾添加didMoveToParent。

示例如下，您可以根據自己的情況做類似的事情。

   NSLayoutConstraint.activateConstraints([
        containerView.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 10),
        containerView.trailingAnchor.constraintEqualToAnchor(view.trailingAnchor, constant: -10),
        containerView.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 10),
        containerView.bottomAnchor.constraintEqualToAnchor(view.bottomAnchor, constant: -10),
    ])


  NSLayoutConstraint.activateConstraints([
        controller.view.leadingAnchor.constraintEqualToAnchor(containerView.leadingAnchor),
        controller.view.trailingAnchor.constraintEqualToAnchor(containerView.trailingAnchor),
        controller.view.topAnchor.constraintEqualToAnchor(containerView.topAnchor),
        controller.view.bottomAnchor.constraintEqualToAnchor(containerView.bottomAnchor)
    ])


controller.didMoveToParentViewController(self)

使用自動布局來設置動態UIView以匹配容器視圖