底部導航抽屜不顯示 (Swift)

Question

我目前正在開發一個 iOS 應用程序，我想使用 material-io 的底部導航抽屜。 所以我做到了，就像 網站上的示例中所解釋的那樣。 但是當我展示導航抽屜時，ViewController 只會變暗一點，並且沒有顯示抽屜的 contentView。

這是我的代碼：

import Foundation
import UIKit
import MaterialComponents

class CreateSubjectView: UIViewController, UITextFieldDelegate {
    ...
    override func viewDidLoad() {
        ...
        let bottomDrawerViewController = MDCBottomDrawerViewController()
        self.modalPresentationStyle = .popover
        let newViewController = self.storyboard?.instantiateViewController(withIdentifier: "TEST")
        bottomDrawerViewController.contentViewController = newViewController

        present(bottomDrawerViewController, animated: true, completion: nil)    
        ...
    }
    ...
}

Answer 1

要在抽屜中顯示的視圖控制器必須指定首選內容大小。

這是最小控制器的演示。 （注意： modalPresentationStyle = .popover對MDCBottomDrawerViewController沒有影響）

使用 Xcode 12 測試

  // button action in parent controller
  @objc private func presentNavigationDrawer() {
    let bottomDrawerViewController = MDCBottomDrawerViewController()
    bottomDrawerViewController.contentViewController = DemoViewController()
    present(bottomDrawerViewController, animated: true, completion: nil)
  }
}

class DemoViewController: UIViewController {

    override func loadView() {
        super.loadView()
        let view = UIView()
        view.backgroundColor = .red
        self.view = view
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        // specify your content preferred height explicitly
        self.preferredContentSize = CGSize(width: 0, height: 400)     // required !!
    }

    @available(iOS 11.0, *)
    override func viewSafeAreaInsetsDidChange() {
        super.viewSafeAreaInsetsDidChange()

        // specify your content preferred height explicitly
        self.preferredContentSize = CGSize(width: 0, height: 400)     // required !!
    }
}

Answer 2

將其移動到viewWillAppear / viewDidAppear一次，因為viewDidLoad呈現 vc 還為時過早

class CreateSubjectView: UIViewController, UITextFieldDelegate {

    let bottomDrawerViewController = MDCBottomDrawerViewController()
    var once = true
    override func viewDidLoad() {
      super.viewDidLoad()

    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        if once {

            let newViewController = self.storyboard?.instantiateViewController(withIdentifier: "TEST")
            bottomDrawerViewController.contentViewController = newViewController
            present(bottomDrawerViewController, animated: true, completion: nil)

            once  = false
        }
    }

}