如果在系统设置中关闭了隐藏字幕，则不会显示字幕

Question

无论设备在辅助功能下设置了什么，我都试图显示字幕。当前，如果设备设置为英语且在设置中启用了隐藏字幕，则将播放英语字幕，如果设备设置为西班牙语，则将播放西班牙语字幕。无论隐藏式字幕是否打开，我都希望播放字幕。

我试图从Apple的文档中添加this code，但没有帮助。似乎可以很好地阅读这些选项，同时检测西班牙语和英语字幕，但我无法在屏幕上显示它们。

import UIKit
import AVFoundation
import AVKit

class ViewController : UIViewController
{
    override func loadView()
    {
        let view = UIView()
        view.backgroundColor = .white

        self.view = view
    }

    override func viewDidLoad()
    {
        super.viewDidLoad()
        guard let path = Bundle.main.path(forResource: "Lebron", ofType:"m4v")
        else
        {
            debugPrint("File not Found")
            return
        }

        let player = AVPlayer(url: URL(fileURLWithPath: path))
        player.appliesMediaSelectionCriteriaAutomatically = false

        let asset = AVAsset(url: URL(fileURLWithPath: path))

        for characteristic in asset.availableMediaCharacteristicsWithMediaSelectionOptions {
            print("\(characteristic)")

            // Retrieve the AVMediaSelectionGroup for the specified characteristic.
            if let group = asset.mediaSelectionGroup(forMediaCharacteristic: characteristic) {
                // Print its options.
                for option in group.options {
                    print("  Option: \(option.displayName)")
                }
            }
        }

        if let group = asset.mediaSelectionGroup(forMediaCharacteristic: AVMediaCharacteristic.legible) {
            let locale = Locale(identifier: "en")
            let options =
                AVMediaSelectionGroup.mediaSelectionOptions(from: group.options, with: locale)
            if let option = options.first {
                // Select Spanish-language subtitle option
                player.currentItem!.select(option, in: group)
                print("\(player.currentItem!.select(option, in: group))")
            }
        }

        let playerViewController = AVPlayerViewController()
        playerViewController.player = player

        addChild(playerViewController)
        playerViewController.view.frame = view.frame
        view.addSubview(playerViewController.view)
        playerViewController.didMove(toParent: self)
        playerViewController.player?.seek(to: CMTime(seconds: 0, preferredTimescale: 1))

    }
}

这是输出到控制台的内容

2019-05-30 21:52:21.432911-0400 subtitleTest[6438:1450671] [Accessibility] ****************** Loading GAX Client Bundle ****************
AVMediaCharacteristic(_rawValue: AVMediaCharacteristicAudible)
  Option: Unknown language
AVMediaCharacteristic(_rawValue: AVMediaCharacteristicLegible)
  Option: Spanish
  Option: Spanish Forced
  Option: English
  Option: English Forced
()

设备应显示与输入语言环境匹配的任何字幕文件，但它根本不显示任何字幕。

Answer 1

我最终完成了这项工作。这是我最终使用的代码。只需将LebronTestProdNamed更改为视频文件的名称，然后将.m4v更改为视频文件的文件类型。

import UIKit
import AVFoundation
import AVKit

class ViewController : UIViewController
{
    override func loadView()
    {
        let view = UIView()
        view.backgroundColor = .white

        self.view = view
    }
    var test = AVPlayerMediaSelectionCriteria()

    override func viewDidLoad()
    {
        super.viewDidLoad()
        guard let path = Bundle.main.path(forResource: "LebronTestProdNamed", ofType:"m4v")
            else
        {
            debugPrint("File not Found")
            return
        }

        let player = AVPlayer(url: URL(fileURLWithPath: path))
        player.appliesMediaSelectionCriteriaAutomatically = false

        let asset = AVAsset(url: URL(fileURLWithPath: path))
        let playerItem = AVPlayerItem(asset: asset)

        for characteristic in asset.availableMediaCharacteristicsWithMediaSelectionOptions {
            print("\(characteristic)")

            // Retrieve the AVMediaSelectionGroup for the specified characteristic.
            if let group = asset.mediaSelectionGroup(forMediaCharacteristic: characteristic) {
                // Print its options.
                for option in group.options {
                    print("  Option: \(option.displayName)")
                }
            }
        }

        // Create a group of the legible AVMediaCharacteristics (Subtitles)
        if let group = asset.mediaSelectionGroup(forMediaCharacteristic: AVMediaCharacteristic.legible) {
            // Set the locale identifier to the value of languageID to select the current language
            let locale = Locale(identifier: "en-EN")
            // Create an option group to hold the options in the group that match the locale
            let options =
                AVMediaSelectionGroup.mediaSelectionOptions(from: group.options, with: locale)
            // Assign the first option from options to the variable option
            if let option = options.first {
                // Select the option for the selected locale
                playerItem.select(option, in: group)
            }
        }



        let playerViewController = AVPlayerViewController()
        playerViewController.player = player
        playerViewController.player?.replaceCurrentItem(with: playerItem)

        addChild(playerViewController)
        playerViewController.view.frame = view.frame
        view.addSubview(playerViewController.view)
        playerViewController.didMove(toParent: self)
        playerViewController.player?.seek(to: CMTime(seconds: 0, preferredTimescale: 1))

    }
}