为 UISearchBar 保留边距

Question

我正在尝试创建 UISearchController 并将其搜索栏放入容器视图中。 searchView 是出口。这是我的代码：

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

    let searchBarBackground = UIImage.roundedImage(UIImage.image(with: #colorLiteral(red: 0.5568627451, green: 0.5568627451, blue: 0.5764705882, alpha: 0.2), size: size), cornerRadius: cornerRadius)
    searchController.searchBar.setSearchFieldBackgroundImage(searchBarBackground, for: .normal)
    searchController.searchBar.searchTextPositionAdjustment = UIOffsetMake(8.0, 0.0)
    searchController.searchBar.searchBarStyle = .minimal
    searchController.searchBar.barStyle = .black
    searchController.searchBar.delegate = self

    searchView.addSubview(searchController.searchBar)

我不知道如何让搜索栏保留主视图的边距。当我尝试向容器视图添加约束并将搜索栏添加为子视图时，搜索栏不遵守尾随约束。

即使手动设置搜索栏框架等于viewDidLayoutSubviews 中的内容视图边界也无济于事。仅当我将前导和尾随约束设置为 0 而不考虑超级视图边距时，它看起来才正常。但它的边距只有 8pt，我需要更多。

我怎样才能实现它？也许可以更改搜索栏的默认边距？谢谢。

如果需要，来自 IB 的屏幕截图（它只是对值 -8 的边距进行限制以补偿搜索栏内部边距）：

Answer 1

我最终得到了以下解决方案：在每次呈现和关闭搜索控制器后更新搜索栏框架，并在 viewDidAppear(_:) 中进行初始设置。

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    searchController?.searchBar.frame.size.width = searchView.bounds.width
}

func didPresentSearchController(_ searchController: UISearchController) {
    searchController.searchBar.frame.size.width = self.searchView.bounds.width
}

func didDismissSearchController(_ searchController: UISearchController) {
    searchController.searchBar.frame.size.width = self.searchView.bounds.width
}

Answer 2

问题在于您以编程方式创建视图并使用自动调整大小掩码。

https://developer.apple.com/documentation/uikit/uiview/1622572-translatesautoresizingmaskintoco

默认情况下，对于您以编程方式创建的任何视图，该属性都设置为 true。

简单的 UISearchBar 示例：

class ViewController: UIViewController, UISearchBarDelegate {

    weak var searchBar: UISearchBar?

    override func viewDidLoad() {
        super.viewDidLoad()

        let searchBar = UISearchBar(frame: .zero)
        self.searchBar = searchBar
        searchBar.searchBarStyle = .minimal
        searchBar.barStyle = .black
        searchBar.delegate = self
        searchBar.translatesAutoresizingMaskIntoConstraints = false

        view.addSubview(searchBar)
        NSLayoutConstraint.activate([
            searchBar.topAnchor.constraint(equalTo: view.topAnchor, constant: 50.0),
            searchBar.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 40.0),
            view.trailingAnchor.constraint(equalTo: searchBar.trailingAnchor, constant: 40.0),
        searchBar.heightAnchor.constraint(equalToConstant: 36.0)
            ])
    }
}