实现iOS的音频输出；修复iOS下钢琴卷帘处无法拖动的问题

[jiPku]

iOS: 实现 AVAudioEngineOutput 并改进 ObjectProvider 初始化流程

iOS 音频输出实现：

• 在 OpenUtauMobile/Platforms/iOS/Utils/Audio/AVAudioEngineOutput.cs 中新增了 AVAudioEngineOutput 类。
  该类基于 AVFoundation 和 NAudio 实现了 IAudioOutput，支持实际音频播放、临时 WAV 渲染以及资源清理。

Object Provider 初始化更新：

• 更新了 OpenUtauMobile/Utils/ObjectProvider.cs 中的 ObjectProvider.Initialize()。
  在 iOS 平台上实例化 AVAudioEngineOutput，若初始化失败则自动回退到 DummyAudioOutput，并记录所选音频输出类型的日志。

[MarMar101]

I think there might be an issue with AVAudioEngine. My song played for a while but then stopped halfway through. My app became +10GB large and I eventually ran out of storage. I am not sure if there is a way to delete the temp WAVs that are already stored on the device. I ran it on an iphone12 mini. I started seeing the following logs over and over listed down below. I had to delete the app and reinstall it.

2026-05-11 01:24:49.625 -05:00 [INF] Rendered temp WAV to /private/var/mobile/Containers/Data/Application/AEF44AC2-8A2A-48D6-BE12-647CD79B0513/tmp/openutaumobile_render_0059adfb-662a-4ecd-9e8e-5210e2f21926.wav
2026-05-11 01:24:50.512 -05:00 [ERR] Failed to render temp WAV for AVAudioEngineOutput
System.IO.IOException: No space left on device : '/private/var/mobile/Containers/Data/Application/AEF44AC2-8A2A-48D6-BE12-647CD79B0513/tmp/openutaumobile_render_4157cd86-3729-47d0-8b31-f0b222d8bd58.wav'
   at System.IO.Strategies.FileStreamHelpers.CheckFileCall(Int64 result, String path, Boolean ignoreNotSupported)
   at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset)
   at System.IO.Strategies.OSFileStreamStrategy.Write(ReadOnlySpan`1 buffer)
   at System.IO.Strategies.OSFileStreamStrategy.Write(Byte[] buffer, Int32 offset, Int32 count)
   at System.IO.Strategies.BufferedFileStreamStrategy.FlushWrite()
   at System.IO.Strategies.BufferedFileStreamStrategy.WriteSpan(ReadOnlySpan`1 source, ArraySegment`1 arraySegment)
   at System.IO.Strategies.BufferedFileStreamStrategy.Write(ReadOnlySpan`1 buffer)
   at System.IO.FileStream.Write(ReadOnlySpan`1 buffer)
   at System.IO.BinaryWriter.Write(Single value)
   at NAudio.Wave.WaveFileWriter.WriteSample(Single sample)
   at OpenUtauMobile.Platforms.iOS.Utils.Audio.AVAudioEngineOutput.Init(ISampleProvider sampleProvider) in /Users/runner/work/OpenUtauMobileIOS/OpenUtauMobileIOS/OpenUtauMobile/Platforms/iOS/Utils/Audio/AVAudioEngineOutput.cs:line 60
2026-05-11 01:24:50.559 -05:00 [ERR] Failed to render temp WAV for AVAudioEngineOutput
System.IO.IOException: No space left on device : '/private/var/mobile/Containers/Data/Application/AEF44AC2-8A2A-48D6-BE12-647CD79B0513/tmp/openutaumobile_render_74213666-e242-4823-98ef-2c9b5fd5015f.wav'
   at System.IO.Strategies.FileStreamHelpers.CheckFileCall(Int64 result, String path, Boolean ignoreNotSupported)
   at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset)
   at System.IO.Strategies.OSFileStreamStrategy.Write(ReadOnlySpan`1 buffer)
   at System.IO.Strategies.OSFileStreamStrategy.Write(Byte[] buffer, Int32 offset, Int32 count)
   at System.IO.Strategies.BufferedFileStreamStrategy.FlushWrite()
   at System.IO.Strategies.BufferedFileStreamStrategy.Flush(Boolean flushToDisk)
   at System.IO.FileStream.Flush(Boolean flushToDisk)
   at System.IO.FileStream.Flush()
   at System.IO.BinaryWriter.Flush()
   at NAudio.Wave.WaveFileWriter.UpdateHeader(BinaryWriter writer)
   at NAudio.Wave.WaveFileWriter.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at OpenUtauMobile.Platforms.iOS.Utils.Audio.AVAudioEngineOutput.Init(ISampleProvider sampleProvider) in /Users/runner/work/OpenUtauMobileIOS/OpenUtauMobileIOS/OpenUtauMobile/Platforms/iOS/Utils/Audio/AVAudioEngineOutput.cs:line 62

[jiPku]

我觉得可能是AVAudioEngine出了问题。我的歌播放了一会儿，但中途就停了。我的应用变得+10GB大，最终存储空间用完了。我不确定有没有办法删除设备上已经存储的临时WAV文件。我是在 iPhone 12 mini 上运行的。我开始在下面反复看到以下日志。我不得不删除应用并重新安装。

2026-05-11 01:24:49.625 -05:00 [INF] Rendered temp WAV to /private/var/mobile/Containers/Data/Application/AEF44AC2-8A2A-48D6-BE12-647CD79B0513/tmp/openutaumobile_render_0059adfb-662a-4ecd-9e8e-5210e2f21926.wav
2026-05-11 01:24:50.512 -05:00 [ERR] Failed to render temp WAV for AVAudioEngineOutput
System.IO.IOException: No space left on device : '/private/var/mobile/Containers/Data/Application/AEF44AC2-8A2A-48D6-BE12-647CD79B0513/tmp/openutaumobile_render_4157cd86-3729-47d0-8b31-f0b222d8bd58.wav'
   at System.IO.Strategies.FileStreamHelpers.CheckFileCall(Int64 result, String path, Boolean ignoreNotSupported)
   at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset)
   at System.IO.Strategies.OSFileStreamStrategy.Write(ReadOnlySpan`1 buffer)
   at System.IO.Strategies.OSFileStreamStrategy.Write(Byte[] buffer, Int32 offset, Int32 count)
   at System.IO.Strategies.BufferedFileStreamStrategy.FlushWrite()
   at System.IO.Strategies.BufferedFileStreamStrategy.WriteSpan(ReadOnlySpan`1 source, ArraySegment`1 arraySegment)
   at System.IO.Strategies.BufferedFileStreamStrategy.Write(ReadOnlySpan`1 buffer)
   at System.IO.FileStream.Write(ReadOnlySpan`1 buffer)
   at System.IO.BinaryWriter.Write(Single value)
   at NAudio.Wave.WaveFileWriter.WriteSample(Single sample)
   at OpenUtauMobile.Platforms.iOS.Utils.Audio.AVAudioEngineOutput.Init(ISampleProvider sampleProvider) in /Users/runner/work/OpenUtauMobileIOS/OpenUtauMobileIOS/OpenUtauMobile/Platforms/iOS/Utils/Audio/AVAudioEngineOutput.cs:line 60
2026-05-11 01:24:50.559 -05:00 [ERR] Failed to render temp WAV for AVAudioEngineOutput
System.IO.IOException: No space left on device : '/private/var/mobile/Containers/Data/Application/AEF44AC2-8A2A-48D6-BE12-647CD79B0513/tmp/openutaumobile_render_74213666-e242-4823-98ef-2c9b5fd5015f.wav'
   at System.IO.Strategies.FileStreamHelpers.CheckFileCall(Int64 result, String path, Boolean ignoreNotSupported)
   at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset)
   at System.IO.Strategies.OSFileStreamStrategy.Write(ReadOnlySpan`1 buffer)
   at System.IO.Strategies.OSFileStreamStrategy.Write(Byte[] buffer, Int32 offset, Int32 count)
   at System.IO.Strategies.BufferedFileStreamStrategy.FlushWrite()
   at System.IO.Strategies.BufferedFileStreamStrategy.Flush(Boolean flushToDisk)
   at System.IO.FileStream.Flush(Boolean flushToDisk)
   at System.IO.FileStream.Flush()
   at System.IO.BinaryWriter.Flush()
   at NAudio.Wave.WaveFileWriter.UpdateHeader(BinaryWriter writer)
   at NAudio.Wave.WaveFileWriter.Dispose(Boolean disposing)
   at System.IO.Stream.Close()
   at System.IO.Stream.Dispose()
   at OpenUtauMobile.Platforms.iOS.Utils.Audio.AVAudioEngineOutput.Init(ISampleProvider sampleProvider) in /Users/runner/work/OpenUtauMobileIOS/OpenUtauMobileIOS/OpenUtauMobile/Platforms/iOS/Utils/Audio/AVAudioEngineOutput.cs:line 62

该Pull request目前仅实现了部分功能以验证部署在iOS平台上的可行性，我们会在项目趋于稳定后重新评估在iOS平台上实现的可能！