要录制音频我会将新视图显示为子视图，录制后我会使用RemoveFromSuperview删除其中的子视图。只是为了描述我如何处理叠加层。
问题是，在使用AVAudioRecorder录制后，应用程序有时会在删除叠加层视图后立即崩溃，有时甚至会在超级视图消失时崩溃。
崩溃日志如下所示：
Incident Identifier: 65BE4068-D7BE-4F3F-B739-00006CAB74CC
CrashReporter Key: d97865bbdce37e60edb2f77974b8b86911a1007e
Hardware Model: iPad4,1
Process: B2MobileBjiOS [8764]
Path: /var/mobile/Applications/3C397A5D-B00B-40CE-BCF8-0C6836B0EBB2/B2MobileBjiOS.app/B2MobileBjiOS
Identifier: ch.bauplus.mobile.bj.trunk
Version: 30 (1.0)
Code Type: ARM (Native)
Parent Process: launchd [1]
Date/Time: 2014-01-20 13:54:04.160 +0100
OS Version: iOS 7.0.4 (11B554a)
Report Version: 104
Exception Type: EXC_BAD_ACCESS (SIGABRT)
Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000000
Triggered by Thread: 0
Thread 0 Crashed:
0 libsystem_kernel.dylib 0x39f8a1fc __pthread_kill + 8
1 libsystem_pthread.dylib 0x39ff1a4f pthread_kill + 55
2 libsystem_c.dylib 0x39f3b029 abort + 73
3 B2MobileBjiOS 0x01607d95 mono_handle_native_sigsegv (mini-exceptions.c:2335)
4 B2MobileBjiOS 0x01612a99 mono_sigsegv_signal_handler (mini.c:6744)
5 libsystem_platform.dylib 0x39fec721 _sigtramp + 41
6 libAVFAudio.dylib 0x2e2db0b3 -[AVAudioRecorder dealloc] + 119
7 libAVFAudio.dylib 0x2e2db0b3 -[AVAudioRecorder dealloc] + 119
8 libobjc.A.dylib 0x399e5b07 objc_object::sidetable_release(bool) + 171
9 B2MobileBjiOS 0x016bfb00 monotouch_release_managed_ref (monotouch-glue.m:1296)
10 B2MobileBjiOS 0x0109629c wrapper_managed_to_native_MonoTouch_Foundation_NSObject_monotouch_release_managed_ref_intptr + 88
11 B2MobileBjiOS 0x00cb31d8 MonoTouch_Foundation_NSObject_ReleaseManagedRef + 28
12 B2MobileBjiOS 0x00cb559c MonoTouch_Foundation_NSObject_NSObject_Disposer_Drain_MonoTouch_Foundation_NSObject + 360
13 B2MobileBjiOS 0x006802cc wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 196
14 B2MobileBjiOS 0x01614b75 mono_jit_runtime_invoke (mini.c:6610)
15 B2MobileBjiOS 0x0165c77b mono_runtime_invoke (object.c:2827)
16 B2MobileBjiOS 0x0158e7e7 native_to_managed_trampoline_MonoTouch_Foundation_NSObject_NSObject_Disposer_Drain (registrar.m:344)
17 Foundation 0x2fd22e47 __NSThreadPerformPerform + 383
18 CoreFoundation 0x2f309f1d __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 13
19 CoreFoundation 0x2f309469 __CFRunLoopDoSources0 + 337
20 CoreFoundation 0x2f307bd3 __CFRunLoopRun + 627
21 CoreFoundation 0x2f27246d CFRunLoopRunSpecific + 521
22 CoreFoundation 0x2f27224f CFRunLoopRunInMode + 103
23 GraphicsServices 0x33f732e7 GSEventRunModal + 135
24 UIKit 0x31b27841 UIApplicationMain + 1133
25 B2MobileBjiOS 0x010e1af8 wrapper_managed_to_native_MonoTouch_UIKit_UIApplication_UIApplicationMain_int_string___intptr_intptr + 268
26 B2MobileBjiOS 0x00d617f4 MonoTouch_UIKit_UIApplication_Main_string___string_string + 296
27 B2MobileBjiOS 0x002062f4 B2.Mobile.Bj.iOS.Application:Main (Main.cs:16)
28 B2MobileBjiOS 0x006802cc wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 196
29 B2MobileBjiOS 0x01614b75 mono_jit_runtime_invoke (mini.c:6610)
30 B2MobileBjiOS 0x0165c77b mono_runtime_invoke (object.c:2827)
31 B2MobileBjiOS 0x016604f9 mono_runtime_exec_main (object.c:4052)
32 B2MobileBjiOS 0x01660349 mono_runtime_run_main (object.c:3678)
33 B2MobileBjiOS 0x015fec5d mono_jit_exec (driver.g.c:1009)
34 B2MobileBjiOS 0x016a95cc main (main.m:489)
35 libdyld.dylib 0x39ed3ab5 start + 1
AudioRecordingOverlay.cs
using System;
using MonoTouch.UIKit;
using System.Diagnostics;
using System.Drawing;
using System.Timers;
using B2.Mobile.Common.iOS;
namespace B2.Mobile.Common.Ui.iOS
{
public class AudioRecordingOverlay : UIView
{
private const int OverlaySize = 120;
private const int ImageSize = 60;
private readonly Timer _timer;
private readonly Stopwatch _stopwatch;
private readonly UITapGestureRecognizer _tapGesture;
private readonly AudioHelper _audioRecorder;
private UIView _overlay;
private UIButton _button;
private UILabel _label;
private string _audioUrl;
public Action<string> ClosedAction { get; set; }
public AudioRecordingOverlay(string filename, RectangleF frame) : base(frame)
{
_stopwatch = new Stopwatch();
_timer = new Timer(1000);
_timer.AutoReset = true;
_timer.Elapsed += HandleElapsed;
_tapGesture = new UITapGestureRecognizer(TapGestureAction);
_audioRecorder = new AudioHelper(filename);
InitializeUI();
}
public void InitializeUI()
{
BackgroundColor = UIColor.FromRGBA(255, 255, 255, 200);
AddGestureRecognizer(_tapGesture);
var xOverlay = (Bounds.Width - OverlaySize) / 2;
var yOverlay = (Bounds.Height - OverlaySize) / 2;
_overlay = new UIView(new RectangleF(xOverlay, yOverlay, OverlaySize, OverlaySize));
_overlay.BackgroundColor = UIColor.FromRGBA(255, 255, 255, 127);
_overlay.Layer.CornerRadius = 5.0f;
_overlay.Layer.BorderWidth = 0.5f;
_overlay.Layer.BorderColor = UIColor.FromRGBA(0, 0, 0, 127).CGColor;
AddSubview(_overlay);
// Start / Stop / Status
var xButton = (OverlaySize - ImageSize) / 2;
var yButton = 20;
_button = new UIButton(UIButtonType.RoundedRect);
_button.Frame = new RectangleF(xButton, yButton, 60, 60);
_button.SetImage(UIImage.FromBundle("Images/microphone-large.png"), UIControlState.Normal);
_button.TouchUpInside += RecordButtonClicked;
_overlay.AddSubview(_button);
// Timer
_label = new UILabel();
_label.Frame = new RectangleF(20, ImageSize + 30, _overlay.Bounds.Width - 40, _label.Font.LineHeight);
_label.TextAlignment = UITextAlignment.Center;
_label.Text = _stopwatch.Elapsed.ToString("mm\\:ss");
_overlay.AddSubview(_label);
}
public void Start()
{
if (_stopwatch.IsRunning)
return;
_stopwatch.Reset();
_stopwatch.Start();
_timer.Start();
_button.TintColor = UIColor.Red;
_audioRecorder.StartRecording();
}
public void Stop()
{
if (!_stopwatch.IsRunning)
return;
_stopwatch.Stop();
_timer.Stop();
_button.TintColor = TintColor;
_audioRecorder.StopRecording();
}
public void Save()
{
_audioUrl = _audioRecorder.Save();
}
public void Discard()
{
_audioRecorder.Discard();
}
public void Close()
{
if (ClosedAction != null)
ClosedAction(_audioUrl);
RemoveFromSuperview();
}
void RecordButtonClicked(object sender, EventArgs eventArgs)
{
if (_stopwatch.IsRunning)
{
Stop();
using (var alert = new UIAlertView("Aufnahme", "Soll die Aufnahme gespeichert werden?", null, "Nein", new[] { "Ja" }))
{
alert.Clicked += (s, e) =>
{
if (e.ButtonIndex == 0)
{
Discard();
}
else
{
Save();
}
Close();
};
alert.Show();
}
}
else
{
Start();
}
}
private void HandleElapsed (object sender, ElapsedEventArgs e)
{
InvokeOnMainThread(() =>
{
_label.Text = _stopwatch.Elapsed.ToString("mm\\:ss");
});
}
private void TapGestureAction(UITapGestureRecognizer recognizer)
{
if (_stopwatch.IsRunning)
{
using (var alert = new UIAlertView("Aufnahme", "Soll die Aufnahme gestoppt und gespeichert werden?", null, "Nein", new[] { "Ja" }))
{
alert.Clicked += (sender, e) =>
{
if (e.ButtonIndex != 0)
{
Stop();
Save();
Close();
}
};
alert.Show();
}
}
else
{
RemoveFromSuperview();
}
}
}
}
AudioHelper.cs
using System;
using MonoTouch.AVFoundation;
using MonoTouch.Foundation;
using System.IO;
namespace B2.Mobile.Common.iOS
{
public class AudioHelper
{
private AVAudioRecorder _recorder;
private readonly string _filename;
private NSUrl _audioUrl;
private AVAudioSession _session;
private AVAudioPlayer _player;
public Action FinishedPlayingAction {get;set;}
public AudioHelper(string filename)
{
_filename = filename;
}
public void Play()
{
NSError error = null;
_player = new AVAudioPlayer(new NSUrl(_filename), error);
_player.PrepareToPlay();
_player.FinishedPlaying += (sender, e) =>
{
if (FinishedPlayingAction != null)
FinishedPlayingAction();
};
_session = AVAudioSession.SharedInstance();
_session.SetCategory(AVAudioSession.CategoryPlayback, out error);
_session.SetActive(true, out error);
_player.Play();
}
public void Continue()
{
if (_player != null)
_player.Play();
}
public void Stop()
{
if (_player != null)
_player.Stop();
}
public void Pause()
{
if (_player != null)
_player.Pause();
}
public void StartRecording()
{
_recorder = new AVAudioRecorder();
_session = AVAudioSession.SharedInstance();
NSError error;
_session.SetCategory(AVAudioSession.CategoryRecord, out error);
if(error != null)
{
Console.WriteLine(error);
return;
}
_session.SetActive(true, out error);
if(error != null)
{
Console.WriteLine(error);
return;
}
if(!PrepareAudioRecording())
{
throw new InvalidOperationException("Aufnahme fehlgeschlagen");
}
if(!_recorder.Record())
{
throw new InvalidOperationException("Aufnahme fehlgeschlagen");
}
}
public void StopRecording()
{
if (!_recorder.Recording)
return;
_recorder.Stop();
}
public string Save()
{
return _audioUrl.Path;
}
public void Discard()
{
try
{
File.Delete(_audioUrl.Path);
}
catch
{
}
}
private bool PrepareAudioRecording()
{
//Declare string for application temp path and tack on the file extension
var tempRecording = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), _filename);
Console.WriteLine(tempRecording);
_audioUrl = NSUrl.FromFilename(tempRecording);
var audioSettings = new AudioSettings
{
SampleRate = 44100.0f,
Format = MonoTouch.AudioToolbox.AudioFormatType.MPEG4AAC,
NumberChannels = 1,
AudioQuality = AVAudioQuality.High
};
//Set recorder parameters
NSError error;
_recorder = AVAudioRecorder.Create(_audioUrl, audioSettings, out error);
if((_recorder == null) || (error != null))
{
Console.WriteLine(error);
return false;
}
//Set Recorder to Prepare To Record
if(!_recorder.PrepareToRecord())
{
_recorder.Dispose();
_recorder = null;
return false;
}
_recorder.FinishedRecording += (sender, e) =>
{
_recorder.Dispose();
_recorder = null;
Console.WriteLine("Done Recording (status: {0})", e.Status);
};
return true;
}
}
}
答案 0 :(得分：1)
问题出在AVAudioRecorder。如果使用对象的构造函数创建不带参数的AVAudioRecorder，则在对象释放时会崩溃。
您可以使用C＃轻松重现崩溃：
var recorder = new AVAudioRecorder();
recorder.Dispose();
或使用Swift（即使在操场上）：
var recorder: AVAudioRecorder? = AVAudioRecorder()
recorder = nil
在代码中，您使用_recorder初始化new AVAudioRecorder();，因此在进行垃圾回收时，您会在处理对象时遇到异常。
只需使用“正确的”构造函数创建记录器。
AVAudioRecorder.Create(NSUrl url, AudioSettings settings, out NSError error);
答案 1 :(得分：0)
在录音机仍在录制时，您可能正在关闭视图。添加对Close函数的停止调用（或使其成为Close），并且在记录器实际停止之前不要调用RemoveFromSuperview。覆盖Dispose函数以查看调用时记录器的状态。
这似乎也是多余的分配：
_recorder = new AVAudioRecorder();
你需要所有这些公共职能吗？保存，关闭，丢弃......？