iOS:添加 subview Controller 不显示子组件

Question

有两个 View Controller ，MainViewController 和 ChildViewController，我想将 ChildViewController 添加到 MainViewController 和这个是我的代码:

MainViewController.swift

class MainViewController: UIViewController {
    
    @IBOutlet weak var containerView: UIView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.add(ChildViewController(), in: containerView)
    }

}

ChildViewController.swift

class ChildViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        print("ChildViewController is loaded")
    }

}

UIViewController+Ext.swift

extension UIViewController {
    func add(_ child: UIViewController, in container: UIView) {
        addChild(child)
        container.addSubview(child.view)
        child.view.frame = container.bounds
        child.didMove(toParent: self)
    }
    
    func add(_ child: UIViewController) {
        add(child, in: view)
    }
    
    func remove(from view: UIView) {
        guard parent != nil else {
            return
        }
        
        willMove(toParent: nil)
        removeFromParent()
        view.removeFromSuperview()
    }
    
    func remove() {
        remove(from: view)
    }
}

Storyboard

输出:

“ChildViewController is loaded”出现在终端中，但未加载 UI 组件。

Answer 1

self.add(ChildViewController(), in: containerView)

您正在以编程方式创建一个 ChildViewController 实例，而不是从 Storyboard 中获取它。

if let childViewController = self.storyboard?.instantiateViewController(withIdentifier: "ChildViewController") {
    self.add(ChildViewController(), in: containerView)
}