ios - 我们如何在不使用 nib 文件的情况下在 iPhone 应用程序中加载用户界面？

Question

我们如何在不使用 nib 文件的情况下在 iPhone 应用程序中加载用户界面？我想使用 .m 文件加载应用程序的用户界面。这可能吗？我们该怎么做。

Answer 1

如果您想以编程方式执行此操作，则 loadView方法用于在不使用 NIB 或 Storyboard时创建 View 。只需在您的 View Controller 中编写一个 loadView 并在那里创建您的 View 。或者让 loadView 创建一个 UIView 子类的实例，并将自定义 View 的大部分代码放入该 UIView 子类中。这是使用 Interface Builder 构建 NIB 或 Storyboard的替代方法。

如果您在 loadView 中执行此操作，只需确保将 self.view 设置为您创建的 View ，然后其余的 View Controller 代码就可以像其他方式一样引用 view 属性。

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参见 Creating a View Programmatically遗留 View Controller Programming Guide 部分。 它概述了基本过程并提供了代码示例。诚然，一些遗留文档并不完全相关(例如，值得注意的是， View 不会在内存压力下“卸载”，因此对 viewDidUnload 的任何引用都不再相关)，但它提供了一些上下文以编程方式创建 View 层次结构。

A View Controller Instantiates Its View Hierarchy When Its View is Accessed [断开的链接] 该指南的部分用于概述基本流程:

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例如，这是一个 Swift 3 示例 loadView，用于以编程方式创建其 View 层次结构的 View Controller :

class ViewController: UIViewController {

    weak var containerView: UIView!
    weak var button: UIButton!

    // Note, when programmatically creating views, you:
    //
    //  - Implement the view hierarchy in `loadView` (not to be confused with `viewDidLoad`)
    //  - Must set `view` property
    //  - Must not call `super.loadView`
    //
    // This example creates a `view` for the view controller, and adds two subviews, a container and a button.
    // Note, the "container" isn't really needed, but I just did it so I could visually demonstrate that the
    // `frame` of the view was set properly. That's why I set it to be a different color of the main `view`
    // and inset it.

    override func loadView() {
        view = UIView()
        view.backgroundColor = #colorLiteral(red: 0.6000000238, green: 0.6000000238, blue: 0.6000000238, alpha: 1)

        let containerView = UIView()
        containerView.backgroundColor = #colorLiteral(red: 0.2549019754, green: 0.2745098174, blue: 0.3019607961, alpha: 1)
        containerView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(containerView)
        self.containerView = containerView

        let button = UIButton(type: .system)
        button.translatesAutoresizingMaskIntoConstraints = false
        button.addTarget(self, action: #selector(didTapButton(_:)), for: .touchUpInside)
        button.setTitle("Back", for: .normal)
        button.setTitleColor(.white, for: .normal)
        containerView.addSubview(button)
        self.button = button

        NSLayoutConstraint.activate([
            containerView.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor, constant: 10),
            containerView.bottomAnchor.constraint(equalTo: bottomLayoutGuide.topAnchor, constant: -10),
            containerView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 10),
            containerView.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -10),

            button.centerXAnchor.constraint(equalTo: containerView.centerXAnchor),
            button.centerYAnchor.constraint(equalTo: containerView.centerYAnchor)
        ])

    }

    func didTapButton(_ sender: Any) {
        // do something
    }

}