Swift，解开nil运行时错误以录制音频

Question

在下面的代码中，我收到一个运行时错误，你可以在这张图片中看到：

在我登录到twitter后，按下Record按钮，然后在下一个ViewController中按下Record按钮。我怀疑原因是不知何故audioRecorder是零并且强制解包时使用！ at＆＃34;如果是self.audioRecorder！.recording＆＃34;，代码崩溃了。但我不明白为什么audioRecorder应该在这里为零。你们有什么想法我做错了吗？ 这是完整的代码。 最好，

import UIKit
import AVFoundation

class RecordViewController: UIViewController {

var audioRecorder : AVAudioRecorder?

func setUpAudioRecorder() {
    do {
        let baseString : String = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true).first!
        let pathComponents = [baseString, "sound.m4a"]
        let audioURL = NSURL.fileURLWithPathComponents(pathComponents)

        let session = AVAudioSession.sharedInstance()
        try session.setCategory(AVAudioSessionCategoryPlayAndRecord)
        try session.overrideOutputAudioPort(AVAudioSessionPortOverride.Speaker)
        try session.setActive(true)

        var recordSettings = [String : AnyObject]()
        recordSettings[AVFormatIDKey] = Int(kAudioFormatMPEG4AAC)
        recordSettings[AVSampleRateKey] = 44100.0
        recordSettings[AVNumberOfChannelsKey] = 2

        self.audioRecorder = try AVAudioRecorder(URL: audioURL!, settings: recordSettings)
        self.audioRecorder!.meteringEnabled = true
        self.audioRecorder!.prepareToRecord()
    } catch (_) {
    }
}

@IBOutlet weak var recordButton: UIButton!
@IBOutlet weak var playButton: UIButton!
@IBOutlet weak var saveButton: UIBarButtonItem!

override func viewDidLoad() {
    super.viewDidLoad()
    self.playButton.enabled = false
    self.saveButton.enabled = false
}

@IBAction func cancelTapped(sender: AnyObject) {
    self.dismissViewControllerAnimated(true, completion: nil)
}

@IBAction func saveTapped(sender: AnyObject) {
}

@IBAction func recordTapped(button: AnyObject) {
    if self.audioRecorder!.recording {
        self.audioRecorder!.stop()
        button.setTitle("Record", forState: UIControlState.Normal)
    } else {
        do{
        try AVAudioSession.sharedInstance().setActive(true)
        self.audioRecorder!.record()
        button.setTitle("Stop Recording", forState: UIControlState.Normal)
        } catch (_) {}
        }
    self.playButton.enabled = true
}

@IBAction func playTapped(sender: AnyObject) {
}

}

Answer 1

哦，小伙子，你是多么正确的节奏拳手。我刚刚调用了IBOutlet中的函数，现在它正在工作。非常感谢您的帮助。 以下是其他任何感兴趣的人的工作代码：

import UIKit
import AVFoundation

class RecordViewController: UIViewController {

var audioRecorder : AVAudioRecorder?

func setUpAudioRecorder() {
    do {
        let baseString : String = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true).first!
        let pathComponents = [baseString, "sound.m4a"]
        let audioURL = NSURL.fileURLWithPathComponents(pathComponents)

        let session = AVAudioSession.sharedInstance()
        try session.setCategory(AVAudioSessionCategoryPlayAndRecord)
        try session.overrideOutputAudioPort(AVAudioSessionPortOverride.Speaker)
        try session.setActive(true)

        var recordSettings = [String : AnyObject]()
        recordSettings[AVFormatIDKey] = Int(kAudioFormatMPEG4AAC)
        recordSettings[AVSampleRateKey] = 44100.0
        recordSettings[AVNumberOfChannelsKey] = 2

        self.audioRecorder = try AVAudioRecorder(URL: audioURL!, settings: recordSettings)
        self.audioRecorder!.meteringEnabled = true
        self.audioRecorder!.prepareToRecord()
    } catch (_) {
    }
}

@IBOutlet weak var recordButton: UIButton!
@IBOutlet weak var playButton: UIButton!
@IBOutlet weak var saveButton: UIBarButtonItem!

override func viewDidLoad() {
    super.viewDidLoad()
    self.playButton.enabled = false
    self.saveButton.enabled = false
}

@IBAction func cancelTapped(sender: AnyObject) {
    self.dismissViewControllerAnimated(true, completion: nil)
}

@IBAction func saveTapped(sender: AnyObject) {
}

@IBAction func recordTapped(button: AnyObject) {
    if (self.audioRecorder?.recording == nil || !self.audioRecorder!.recording) {
        if (self.audioRecorder?.recording == nil) {
            setUpAudioRecorder()
        }
        do {
            try AVAudioSession.sharedInstance().setActive(true)
            self.audioRecorder!.record()
            button.setTitle("Stop Recording", forState: UIControlState.Normal)
        } catch (_) {}
    } else {
        self.audioRecorder!.stop()
        button.setTitle("Record", forState: UIControlState.Normal)
    }
    self.playButton.enabled = true
}

@IBAction func playTapped(sender: AnyObject) {
}

}