我有一个来自框架SwiftySound的名为Sound的类和一个名为SoundWrapper的子类，使其可哈希。现在我要添加一个字符串属性&;imagename &;到子类中，这样我就可以为每个声音添加一个图像。因此，我需要使用super.init为超类编写一个初始化器。
然而，当我尝试这样做时，错误显示:'url'由于'private'保护级别而无法访问。
有办法解决这个问题吗?
需要说明的是，这是我第一次在Swift中创建子类，所以我可能会犯一些明显的错误，可能需要完全不同的方法。
这是我的子类:
class SoundWrapper:Sound, Hashable{
let id = UUID()
let imageName : String
init(imageName: String) {
self.imageName = imageName
super.init(url: url)
// Error: 'url' is inaccessible due to 'private' protection level
}
public func hash(into hasher: inout Hasher) {
hasher.combine(0)
}
static func == (lhs: SoundWrapper, rhs: SoundWrapper) -> Bool {
return lhs.id == rhs.id
}
}
我计划如何初始化子类:
let backgroundAudio1 = SoundWrapper(imageName: "image1", url: getFileUrl(name: "backgroundAudio1"))
如何获得url:
func getFileUrl (name: String) -> URL {
let filePath = Bundle.main.path(forResource: name, ofType: "wav")!
return URL(fileURLWithPath: filePath)
}
这是SwiftySound框架，我从那里得到的声音类:
import Foundation
import AVFoundation
#if os(iOS) || os(tvOS)
/// SoundCategory is a convenient wrapper for AVAudioSessions category constants.
public enum SoundCategory {
/// Equivalent of AVAudioSession.Category.ambient.
case ambient
/// Equivalent of AVAudioSession.Category.soloAmbient.
case soloAmbient
/// Equivalent of AVAudioSession.Category.playback.
case playback
/// Equivalent of AVAudioSession.Category.record.
case record
/// Equivalent of AVAudioSession.Category.playAndRecord.
case playAndRecord
fileprivate var avFoundationCategory: AVAudioSession.Category {
get {
switch self {
case .ambient:
return .ambient
case .soloAmbient:
return .soloAmbient
case .playback:
return .playback
case .record:
return .record
case .playAndRecord:
return .playAndRecord
}
}
}
}
#endif
/// Sound is a class that allows you to easily play sounds in Swift. It uses AVFoundation framework under the hood.
open class Sound {
// MARK: - Global settings
/// Number of AVAudioPlayer instances created for every sound. SwiftySound creates 5 players for every sound to make sure that it will be able to play the same sound more than once. If your app doesn't need this functionality, you can reduce the number of players to 1 and reduce memory usage. You can increase the number if your app plays the sound more than 5 times at the same time.
public static var playersPerSound: Int = 10 {
didSet {
stopAll()
sounds.removeAll()
}
}
#if os(iOS) || os(tvOS)
/// Sound session. The default value is the shared `AVAudioSession` session.
public static var session: Session = AVAudioSession.sharedInstance()
/// Sound category for current session. Using this variable is a convenient way to set AVAudioSessions category. The default value is .ambient.
public static var category: SoundCategory = {
let defaultCategory = SoundCategory.ambient
try? session.setCategory(defaultCategory.avFoundationCategory)
return defaultCategory
}() {
didSet {
try? session.setCategory(category.avFoundationCategory)
}
}
#endif
private static var sounds = [URL: Sound]()
private static let defaultsKey = "com.moonlightapps.SwiftySound.enabled"
/// Globally enable or disable sound. This setting value is stored in UserDefaults and will be loaded on app launch.
public static var enabled: Bool = {
return !UserDefaults.standard.bool(forKey: defaultsKey)
}() { didSet {
let value = !enabled
UserDefaults.standard.set(value, forKey: defaultsKey)
if value {
stopAll()
}
}
}
private let players: [Player]
private var counter = 0
/// The class that is used to create `Player` instances. Defaults to `AVAudioPlayer`.
public static var playerClass: Player.Type = AVAudioPlayer.self
/// The bundle used to load sounds from filenames. The default value of this property is Bunde.main. It can be changed to load sounds from another bundle.
public static var soundsBundle: Bundle = .main
// MARK: - Initialization
/// Create a sound object.
///
/// - Parameter url: Sound file URL.
public init?(url: URL) {
#if os(iOS) || os(tvOS)
_ = Sound.category
#endif
let playersPerSound = max(Sound.playersPerSound, 1)
var myPlayers: [Player] = []
myPlayers.reserveCapacity(playersPerSound)
for _ in 0..<playersPerSound {
do {
let player = try Sound.playerClass.init(contentsOf: url)
myPlayers.append(player)
} catch {
print("SwiftySound initialization error: (error)")
}
}
if myPlayers.count == 0 {
return nil
}
players = myPlayers
NotificationCenter.default.addObserver(self, selector: #selector(Sound.stopNoteRcv), name: Sound.stopNotificationName, object: nil)
}
deinit {
NotificationCenter.default.removeObserver(self, name: Sound.stopNotificationName, object: nil)
}
@objc private func stopNoteRcv() {
stop()
}
private static let stopNotificationName = Notification.Name("com.moonlightapps.SwiftySound.stopNotification")
// MARK: - Main play method
/// Play the sound.
///
/// - Parameter numberOfLoops: Number of loops. Specify a negative number for an infinite loop. Default value of 0 means that the sound will be played once.
/// - Returns: If the sound was played successfully the return value will be true. It will be false if sounds are disabled or if system could not play the sound.
@discardableResult public func play(numberOfLoops: Int = 0, completion: PlayerCompletion? = nil) -> Bool {
if !Sound.enabled {
return false
}
paused = false
counter = (counter + 1) % players.count
let player = players[counter]
return player.play(numberOfLoops: numberOfLoops, completion: completion)
}
// MARK: - Stop playing
/// Stop playing the sound.
public func stop() {
for player in players {
player.stop()
}
paused = false
}
/// Pause current playback.
public func pause() {
players[counter].pause()
paused = true
}
/// Resume playing.
@discardableResult public func resume() -> Bool {
if paused {
players[counter].resume()
paused = false
return true
}
return false
}
/// Indicates if the sound is currently playing.
public var playing: Bool {
return players[counter].isPlaying
}
/// Indicates if the sound is paused.
public private(set) var paused: Bool = false
// MARK: - Prepare sound
/// Prepare the sound for playback
///
/// - Returns: True if the sound has been prepared, false in case of error
@discardableResult public func prepare() -> Bool {
let nextIndex = (counter + 1) % players.count
return players[nextIndex].prepareToPlay()
}
// MARK: - Convenience static methods
/// Play sound from a sound file.
///
/// - Parameters:
/// - file: Sound file name.
/// - fileExtension: Sound file extension.
/// - numberOfLoops: Number of loops. Specify a negative number for an infinite loop. Default value of 0 means that the sound will be played once.
/// - Returns: If the sound was played successfully the return value will be true. It will be false if sounds are disabled or if system could not play the sound.
@discardableResult public static func play(file: String, fileExtension: String? = nil, numberOfLoops: Int = 0) -> Bool {
if let url = url(for: file, fileExtension: fileExtension) {
return play(url: url, numberOfLoops: numberOfLoops)
}
return false
}
/// Play a sound from URL.
///
/// - Parameters:
/// - url: Sound file URL.
/// - numberOfLoops: Number of loops. Specify a negative number for an infinite loop. Default value of 0 means that the sound will be played once.
/// - Returns: If the sound was played successfully the return value will be true. It will be false if sounds are disabled or if system could not play the sound.
@discardableResult public static func play(url: URL, numberOfLoops: Int = 0) -> Bool {
if !Sound.enabled {
return false
}
var sound = sounds[url]
if sound == nil {
sound = Sound(url: url)
sounds[url] = sound
}
return sound?.play(numberOfLoops: numberOfLoops) ?? false
}
/// Stop playing sound for given URL.
///
/// - Parameter url: Sound file URL.
public static func stop(for url: URL) {
let sound = sounds[url]
sound?.stop()
}
/// Duration of the sound.
public var duration: TimeInterval {
get {
return players[counter].duration
}
}
/// Sound volume.
/// A value in the range 0.0 to 1.0, with 0.0 representing the minimum volume and 1.0 representing the maximum volume.
public var volume: Float {
get {
return players[counter].volume
}
set {
for player in players {
player.volume = newValue
}
}
}
/// Stop playing sound for given sound file.
///
/// - Parameters:
/// - file: Sound file name.
/// - fileExtension: Sound file extension.
public static func stop(file: String, fileExtension: String? = nil) {
if let url = url(for: file, fileExtension: fileExtension) {
let sound = sounds[url]
sound?.stop()
}
}
/// Stop playing all sounds.
public static func stopAll() {
NotificationCenter.default.post(name: stopNotificationName, object: nil)
}
// MARK: - Private helper method
private static func url(for file: String, fileExtension: String? = nil) -> URL? {
return soundsBundle.url(forResource: file, withExtension: fileExtension)
}
}
/// Player protocol. It duplicates `AVAudioPlayer` methods.
public protocol Player: AnyObject {
/// Play the sound.
///
/// - Parameters:
/// - numberOfLoops: Number of loops.
/// - completion: Complation handler.
/// - Returns: true if the sound was played successfully. False otherwise.
func play(numberOfLoops: Int, completion: PlayerCompletion?) -> Bool
/// Stop playing the sound.
func stop()
/// Pause current playback.
func pause()
/// Resume playing.
func resume()
/// Prepare the sound.
func prepareToPlay() -> Bool
/// Create a Player for sound url.
///
/// - Parameter url: sound url.
init(contentsOf url: URL) throws
/// Duration of the sound.
var duration: TimeInterval { get }
/// Sound volume.
var volume: Float { get set }
/// Indicates if the player is currently playing.
var isPlaying: Bool { get }
}
fileprivate var associatedCallbackKey = "com.moonlightapps.SwiftySound.associatedCallbackKey"
public typealias PlayerCompletion = ((Bool) -> ())
extension AVAudioPlayer: Player, AVAudioPlayerDelegate {
public func play(numberOfLoops: Int, completion: PlayerCompletion?) -> Bool {
if let cmpl = completion {
objc_setAssociatedObject(self, &associatedCallbackKey, cmpl, .OBJC_ASSOCIATION_COPY_NONATOMIC)
self.delegate = self
}
self.numberOfLoops = numberOfLoops
return play()
}
public func resume() {
play()
}
public func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
let cmpl = objc_getAssociatedObject(self, &associatedCallbackKey) as? PlayerCompletion
cmpl?(flag)
objc_removeAssociatedObjects(self)
self.delegate = nil
}
public func audioPlayerDecodeErrorDidOccur(_ player: AVAudioPlayer, error: Error?) {
print("SwiftySound playback error: (String(describing: error))")
}
}
#if os(iOS) || os(tvOS)
/// Session protocol. It duplicates `setCategory` method of `AVAudioSession` class.
public protocol Session: AnyObject {
/// Set category for session.
///
/// - Parameter category: category.
func setCategory(_ category: AVAudioSession.Category) throws
}
extension AVAudioSession: Session {}
#endif
Sound提供了一个期望URL形参的公共初始化器。您的包装器还需要接受一个URL参数，以便它可以传递它。
init(imageName: String, url: URL) {
self.imageName = imageName
super.init(url: url)
}
创建Sound实例时需要URL。在创建SoundWrapper实例时，您将需要相同的URL。
还要注意，在所有实例中使用0时，hash的效率很低。为什么不用id呢?
public func hash(into hasher: inout Hasher) {
hasher.combine(id)
}
你没有在SoundWrapper的任何地方定义url，所以Swift编译器试图找到url在其他地方定义的地方。我相信它是在Sound:private static func url(for file: String, fileExtension: String? = nil) -> URL?上找到私有方法并告诉你它是私有的。
所以问题是，你想要传递什么url到Sound基类初始化器?
我想象您的SoundWrapper初始化器将被更改为如下内容:
init(imageName: String) {
self.imageName = imageName
super.init(url: URL(string: "example.com")!)
// or use a URL defined on your class or somewhere else
}