约束从视图中删除SegmentController [英] Constraints Removing SegmentController from view

问题描述

我有一个 UICollectionView 和一个 SegmentController 。

所需的最终结果：

SegmentController 完全可见， UICollectionView 在其下方

在添加约束之前：

添加约束后（注意 SegmentController 几乎完全隐藏了）：

After adding constraints (Notice the SegmentController is almost entirely hidden):

添加的约束：

ProductsCollection.removeConstraints（ProductsCollection.constraints）
SegmentController.translatesAutoresizingMaskIntoConstraints = false

ProductsCollection.removeConstraints(ProductsCollection.constraints) SegmentController.translatesAutoresizingMaskIntoConstraints = false

NSLayoutConstraint.activate([
    SegmentController.centerXAnchor.constraint(equalTo: view.centerXAnchor),
    SegmentController.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor, constant: 100),
    //ProductsCollection.topAnchor.constraint(equalTo: SegmentController.bottomAnchor, constant: 10),
    ProductsCollection.leftAnchor.constraint(equalTo: view.leftAnchor),
    ProductsCollection.rightAnchor.constraint(equalTo: view.rightAnchor),
    ProductsCollection.bottomAnchor.constraint(equalTo: view.bottomAnchor)
    ])

我猜问题是我没有添加SegmentController约束，但是添加时我得到了相同的结果：

I am guessing the problem is I did not add SegmentController constraints, but I had same result when I added :

SegmentController.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor, constant: 100),
SegmentController.centerXAnchor.constraint(equalTo: view.centerXAnchor),

编辑：

此视图继承自另一个视图ne，具有：

This view inherits from another one, which has :

    private func createProductsCollection()
        {
            let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
            layout.itemSize = CGSize(width: 200, height: 250)

            self.ProductsCollection = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)

            ProductsCollection.dataSource = self
            ProductsCollection.delegate = self
            ProductsCollection.register(ProductsCollectionViewCell.self, forCellWithReuseIdentifier: "product_collection_cell")
            ProductsCollection.backgroundColor = UIColor.clear
            self.view.addSubview(ProductsCollection)

ProductsCollection.translatesAutoresizingMaskIntoConstraints = false

NSLayoutConstraint.activate([
                NSLayoutConstraint(item: ProductsCollection, attribute: .top, relatedBy: .equal, toItem: self.view, attribute: .top, multiplier: 1, constant: 20),
                NSLayoutConstraint(item: ProductsCollection, attribute: .bottom, relatedBy: .equal, toItem: self.view, attribute: .bottom, multiplier: 1, constant: -50), //leaving space for search field
                NSLayoutConstraint(item: ProductsCollection, attribute: .leading, relatedBy: .equal, toItem: self.view, attribute: .leading, multiplier: 1, constant: 0),
                NSLayoutConstraint(item: ProductsCollection, attribute: .trailing, relatedBy: .equal, toItem: self.view, attribute: .trailing, multiplier: 1, constant: 0)
                ])
        }

编辑＃2：

我是现在使用以下约束：

I am now using these constraints:

SegmentController.translatesAutoresizingMaskIntoConstraints = false
        SegmentController.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor).isActive = true
        SegmentController.heightAnchor.constraint(equalToConstant: 40).isActive = true
        SegmentController.widthAnchor.constraint(equalToConstant: 120).isActive = true
        SegmentController.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true

        self.view.addSubview(ProductsCollection)
        ProductsCollection.translatesAutoresizingMaskIntoConstraints = false
        ProductsCollection.topAnchor.constraint(equalTo: self.SegmentController.bottomAnchor).isActive = true
        ProductsCollection.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
        ProductsCollection.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
        ProductsCollection.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true

我的视图现在看起来像：

And my view now looks like :

推荐答案

您的约束不正确。它不应为 self.view.safeAreaLayoutGuide.bottomAnchor 它应为 self.view.safeAreaLayoutGuide.topAnchor 。检查究竟是什么安全区域指南。从苹果公司购买：

Your constraints are not correct. It should not be self.view.safeAreaLayoutGuide.bottomAnchor It should be self.view.safeAreaLayoutGuide.topAnchor. Check what exactly safe area guide gives. From Apple:

布局指南表示视图中被
遮挡的部分，没有酒吧和其他内容。

The layout guide representing the portion of your view that is unobscured by bars and other content.

从中可以很容易地得知它是边距内的区域。

From that it is easy to get that it is the area inside of the "margins".

EDIT

        self.view.addSubview(segmentController)
        segmentController.translatesAutoresizingMaskIntoConstraints = false
        segmentController.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor).isActive = true
        segmentController.heightAnchor.constraint(equalToConstant: 40).isActive = true
        segmentController.widthAnchor.constraint(equalToConstant: 120).isActive = true
        segmentController.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true

        self.view.addSubview(collectionView)
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        collectionView.topAnchor.constraint(equalTo: self.segmentController.bottomAnchor).isActive = true
        collectionView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
        collectionView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
        collectionView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true 

您还需要删除此框架

self.ProductsCollection = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)

将其更改为 frame：.zero 其余部分应该由约束来完成

Change it to frame: .zero And the contraints should do the rest

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