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我目前正在编写在播放 AVAudioPlayer 时禁用 UIImageView 的代码。我要禁用的 AVAudioPlayer 和 ImageView 位于两个不同的类中。我尝试编写一个委托(delegate)来让我的两个类进行通信，但是当我尝试在我的 viewController 中分配给自己时，我不断收到错误“线程 1: fatal error :在展开可选值时意外发现 nil”。
包含我的 AVAudioPlayer 的类的代码如下
import Foundation; import UIKit; import AVFoundation
protocol isOnProtocol{
func isOn()
}
class Card: NSObject
{
var delegate: isOnProtocol?
var player: AVAudioPlayer?
var image: UIImage
var soundUrl: String
init(image: UIImage, soundUrl: String, isActive:Bool = true) {
self.image = image
self.soundUrl = soundUrl
}
func playSound()
{
guard let url = Bundle.main.url(forResource: self.soundUrl, withExtension: "m4a") else { return }
do
{
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
try AVAudioSession.sharedInstance().setActive(true)
player = try AVAudioPlayer(contentsOf: url)
//player?.delegate = self
guard let player = player else { return }
player.prepareToPlay()
player.play()
audioPlayerDidFinishPlaying(player)
print("play")
} catch let error {
print(error.localizedDescription)
}
}
}
extension Card: AVAudioPlayerDelegate {
func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer){
if let del = delegate{
del.isOn()
}else{
print("the delegate is not set")
}
}
}
我尝试与之通信的 ViewController 的代码如下。当调用图像点击函数时，声音播放并且 UserInteractions 应该为假，直到 AVAudioPlayer 完成(调用 isOn 函数)。
class SecondViewController: UIViewController , UIGestureRecognizerDelegate, isOnProtocol {
@IBOutlet weak var imgPhoto: UIImageView!
var card: Card!
override func viewDidLoad() {
super.viewDidLoad()
card.delegate = self //error is thrown here
}
func imageTapped(tapGestureRecognizer: UITapGestureRecognizer)
{
imgPhoto.isUserInteractionEnabled = false
itemList[imageIndex].playSound()
}
func isOn() {
imgPhoto.isUserInteractionEnabled = true
}
}