ios - 如何将 UITableView 的顶部粘贴到 UISearchBar 的底部？

Question

我有一个 UTableView：

tableView = UITableView()
        tableView.dataSource = self
        tableView.delegate = self
        tableView.register(UINib(nibName: "TableViewCell", bundle: nil), forCellReuseIdentifier: "Cell")
        tableView.rowHeight = 60.0
        tableView.tableFooterView = UIView()
        view.addSubview(tableView)

        tableView.translatesAutoresizingMaskIntoConstraints = false

        tableViewHeightAnchor = tableView.heightAnchor.constraint(equalToConstant: 0)
        let constraints = [tableView.topAnchor.constraint(equalTo: view.topAnchor), tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor), tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor), tableViewHeightAnchor!]
        NSLayoutConstraint.activate(constraints)

我的搜索栏是：

    searchController = UISearchController(searchResultsController: nil)
    searchController.searchResultsUpdater = self
    searchController.searchBar.delegate = self
    searchController.obscuresBackgroundDuringPresentation = false
    searchController.searchBar.placeholder = "Search for a cell"
    navigationItem.searchController = searchController
    definesPresentationContext = true

但我希望将我的顶级锚设置为：

tableView.topAnchor.constraint(equalTo: searchController.searchBar.bottomAnchor)

但不是：

tableView.topAnchor.constraint(equalTo: view.topAnchor)

但是当我将它粘贴到 searchBar 的底部锚点时，应用程序由于层次结构不同而崩溃。

'Unable to activate constraint with anchors <NSLayoutYAxisAnchor:0x6000017a6cc0 "UITableView:0x7f81c4876e00.top"> and <NSLayoutYAxisAnchor:0x6000017a6dc0 "_UISearchControllerView:0x7f81c2d3fa30.bottom"> because they have no common ancestor.  Does the constraint or its anchors reference items in different view hierarchies?  That's illegal.'

我该如何解决这个问题？我已经尝试解决这个问题 3 天但没有成功

标签： iosswiftconstraints

Answer 1

选项 A（导航栏中的搜索栏）：

let tableView = UITableView()
view.addSubview(tableView)

let searchController = UISearchController(searchResultsController: nil)
navigationItem.searchController = searchController

definesPresentationContext = true

tableView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
    tableView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
    tableView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
    tableView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
    tableView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
])

选项 B（搜索栏作为表头视图）：

let tableView = UITableView()
view.addSubview(tableView)

let searchController = UISearchController(searchResultsController: nil)
tableView.tableHeaderView = searchController.searchBar

definesPresentationContext = true

tableView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
    tableView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
    tableView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
    tableView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
    tableView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
])