ios怎么后台录像

要在 iOS 设备上实现后台录像,需要使用 AVFoundation 框架提供的功能。以下是一个简单的示例代码:

```swift

import AVFoundation

class BackgroundRecorder {

private var videoRecorder: AVAssetWriter?

private var videoInput: AVAssetWriterInput?

private var audioInput: AVAssetWriterInput?

private var videoQueue = DispatchQueue(label: "com.example.video-queue")

private var audioQueue = DispatchQueue(label: "com.example.audio-queue")

func startRecording() {

guard let videoDevice = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .back),

let audioDevice = AVCaptureDevice.default(for: .audio) else {

return

}

do {

let videoInput = try AVCaptureDeviceInput(device: videoDevice)

let audioInput = try AVCaptureDeviceInput(device: audioDevice)

let writer = try AVAssetWriter(outputURL: URL(fileURLWithPath: NSTemporaryDirectory() + "output.mov"), fileType: .mov)

writer.shouldOptimizeForNetworkUse = true

self.videoInput = AVAssetWriterInput(mediaType: .video, outputSettings: [

AVVideoCodecKey: AVVideoCodecType.h264,

AVVideoWidthKey: 1920,

AVVideoHeightKey: 1080,

AVVideoCompressionPropertiesKey: [

AVVideoAverageBitRateKey: 3_000_000

]

])

self.audioInput = AVAssetWriterInput(mediaType: .audio, outputSettings: [

AVFormatIDKey: kAudioFormatMPEG4AAC,

AVSampleRateKey: 44100,

AVNumberOfChannelsKey: 2,

AVEncoderBitRateKey: 128_000

])

writer.add(self.videoInput!)

writer.add(self.audioInput!)

writer.startWriting()

writer.startSession(atSourceTime: .zero)

self.videoRecorder = writer

} catch {

print("Error starting recording: \(error)")

}

}

func stopRecording() {

videoInput?.markAsFinished()

audioInput?.markAsFinished()

videoRecorder?.finishWriting(completionHandler: { [weak self] in

print("Recording finished")

self?.videoRecorder = nil

})

}

func captureVideoSample(_ sampleBuffer: CMSampleBuffer) {

videoQueue.async {

self.videoInput?.append(sampleBuffer)

}

}

func captureAudioSample(_ sampleBuffer: CMSampleBuffer) {

audioQueue.async {

self.audioInput?.append(sampleBuffer)

}

}

}

```

这个代码示例展示了如何使用 AVFoundation 框架在后台录制视频和音频。需要注意的是,您需要在应用程序的 Info.plist 文件中添加权限请求,如 NSCameraUsageDescription 和 NSMicrophoneUsageDescription,以便用户可以授予相应的权限。

此外,您还需要在应用程序的生命周期中适当地管理录制的状态,例如在应用程序进入后台时暂停录制,在应用程序回到前台时恢复录制。