AVAudioFile init 在模拟器上工作但在设备上崩溃

Question

我想构建一个 iOS 应用程序（使用 Swift 3 和 Xcode 8.2.1）从 iPhone 的麦克风录音并保存录音到 .caf 文件。

首先，我在项目的 Info.plist 文件中添加了以下行：

<key>NSMicrophoneUsageDescription</key>
<string>Some description to explain why access is required</string>

然后，我创建了一个简单的 UIViewController，当点击 Record 和 Stop 按钮时，它设置了 AVAudioEngine 和 install/remove 音频点击.

ViewController.swift

import UIKit
import AVFoundation

class ViewController: UIViewController {

    var engine = AVAudioEngine()
    var file: AVAudioFile?
    var player = AVAudioPlayerNode()

    override func viewDidLoad() {
        super.viewDidLoad()

        guard let url = urlFor(filename: "test.caf") else { return }
        do {
            file = try AVAudioFile(forWriting: url, settings: engine.inputNode!.inputFormat(forBus: 0).settings, commonFormat: engine.inputNode!.inputFormat(forBus: 0).commonFormat, interleaved: false)
        } catch {
            print("Error: \(error)")
        }

        engine.attach(player)
        engine.connect(player, to: engine.mainMixerNode, format: engine.mainMixerNode.outputFormat(forBus: 0))

        do {
            try engine.start()
        } catch {
            print("Error: \(error)")
        }
    }

    @IBAction func record(sender: AnyObject) {
        engine.inputNode?.installTap(onBus: 0, bufferSize: 1024, format: engine.mainMixerNode.outputFormat(forBus: 0)) { (buffer, time) -> Void in
            do {
                try self.file?.write(from: buffer)
            } catch {
                print("Error: \(error)")
            }
        }
    }

    @IBAction func stop(sender: AnyObject) {
        engine.inputNode?.removeTap(onBus: 0)
        // Print the url of the saved file
        let urls = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)
        print(urls[urls.endIndex - 1])
    }

    func urlFor(filename: String) -> URL? {
        // Get url of saved file
        if let dir = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.allDomainsMask, true).first {
            let path = dir.appending(filename)
            return URL(fileURLWithPath: path)
        }
        return nil
    }

}

该应用程序在模拟器上运行良好：我可以录制我的声音，抓取录制文件的 url 并测试我的声音是否已正确录制。但是，当我在设备上启动该应用程序时，该应用程序立即崩溃（在 iOS 10.2.1 上使用 iPhone 6s 进行测试）。控制台为我提供了以下日志：

2017-02-08 17:09:14.330151 AudioEngineSimpleApp[7100:2659416] Audio files cannot be non-interleaved. Ignoring setting AVLinearPCMIsNonInterleaved YES.
2017-02-08 17:09:14.333715 AudioEngineSimpleApp[7100:2659416] [central] 54:   ERROR:    [0x1b7440c40] >avae> AVAudioFile.mm:160: AVAudioFileImpl: error -54
2017-02-08 17:09:14.333796 AudioEngineSimpleApp[7100:2659416] [central] 54:   ERROR:    [0x1b7440c40] >avae> AVAudioFile.mm:122: ReadMagicCookie: error -50
2017-02-08 17:09:14.334369 AudioEngineSimpleApp[7100:2659416] *** Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'error -50'

这个问题似乎与 Stack Overflow 线程有关但我不知道如何将其响应实现到我自己的代码中以解决我的问题。

Answer 1

我重构了我的代码，并将我的旧 urlFor(filename: String) -> URL? 方法替换为以下 url 属性:

let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("test.caf")

因此，以下代码可在设备上正常运行：

import UIKit
import AVFoundation

class ViewController: UIViewController {

    @IBOutlet weak var recordButton: UIButton!
    let url = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("test.caf")
    //let url = URL(fileURLWithPath: NSTemporaryDirectory().appending("test.caf")) also works
    var engine = AVAudioEngine()

    override func viewDidLoad() {
        super.viewDidLoad()

        recordButton.setTitle("Record", for: .normal)

        let file: AVAudioFile
        do {
            file = try AVAudioFile(forWriting: url, settings: engine.inputNode!.outputFormat(forBus: 0).settings)
        } catch {
            print("Error: \(error)")
            return
        }

        engine.inputNode?.installTap(onBus: 0, bufferSize: 1024, format: engine.inputNode!.outputFormat(forBus: 0)) { (buffer, time) -> Void in
            do {
                try file.write(from: buffer)
            } catch {
                print("Error: \(error)")
            }
        }
    }

    @IBAction func toggleAction(_ sender: AnyObject) {
        engine.isRunning ? stopRecording() : startRecording()
    }

    func startRecording() {
        do {
            // Start engine
            try engine.start()

            // Toggle button title
            recordButton.setTitle("Stop", for: .normal)
        } catch {
            print("Error: \(error)")
        }
    }

    func stopRecording() {
        // Stop engine
        engine.stop()

        // Toggle button title
        recordButton.setTitle("Record", for: .normal)

        print(url)
    }

}

AVAudioFile init 在模拟器上工作但在设备上崩溃

AVAudioFile init works on simulator but crashes on device

avfoundation

ios

swift

avaudioengine

avaudiofile