iOS10相机API适配一

iOS10在拍照方面的API主要有以下几个亮点:

• 部分机型支持LivePhoto的拍摄和编辑
• 部分机型支持RawPhoto的拍摄和编辑
• 支持拍照时快速获取预览图

LivePhoto拍摄

• 创建AVCapturePhotoOutput
• 添加AudioInput
• 设置livePhotoCaptureEnabled属性为YES
• 创建AVCapturePhotoSettings实例，并设置livePhotoMovieFileURL属性
• 获取LivePhoto数据

- (void)captureOutput:(AVCapturePhotoOutput *)captureOutput
didFinishProcessingLivePhotoToMovieFileAtURL:(NSURL *)outputFileURL
             duration:(CMTime)duration
     photoDisplayTime:(CMTime)photoDisplayTime
     resolvedSettings:(AVCaptureResolvedPhotoSettings *)resolvedSettings
                error:(NSError *)error
{
	 // do something...
}

注意:

• 必须将AVCapturePhotoOutput实例先加入AVCaptureSession的output中，再设置livePhotoMovieFileURL,否则会设置失败.
• LivePhoto只支持分辨率模式为AVCaptureSessionPresetPhoto
• LivePhoto的本质就是一个视频文件

RawPhoto拍摄

• 创建AVCapturePhotoOutput

• 设置FormatType

NSUInteger rawFormat = photoOutput.availableRawPhotoPixelFormatTypes.firstObject.unsignedIntegerValue;
photoSettings = [AVCapturePhotoSettings photoSettingsWithRawPixelFormatType:(OSType)rawFormat];

• 保存DNG文件

- (void)captureOutput:(AVCapturePhotoOutput *)captureOutput
didFinishProcessingRawPhotoSampleBuffer:(CMSampleBufferRef)rawSampleBuffer
previewPhotoSampleBuffer:(CMSampleBufferRef)previewPhotoSampleBuffer
     resolvedSettings:(AVCaptureResolvedPhotoSettings *)resolvedSettings
      bracketSettings:(AVCaptureBracketedStillImageSettings *)bracketSettings
                error:(NSError *)error {
    NSData *data = [AVCapturePhotoOutput DNGPhotoDataRepresentationForRawSampleBuffer:rawSampleBuffer previewPhotoSampleBuffer:previewPhotoSampleBuffer];
    NSString *filePath = [dir stringByAppendingPathExtension:@"dng"];
    [data writeToFile:filePath atomically:YES];
    // do something...
}

获取快速预览图

• 在代理方法中通过参数能够获取preview的sampleBuffer
• 有个问题是这个sampleBuffer并不是压缩过的JPEG数据，也没有Exif信息，所以并不能通过这个数据获取预览图的方向信息，我能想到的解决办法有两个: 1) 通过原片的Exif信息来处理预览图。2) 通过拍照时一瞬间的设备方向来纠正方向。

- (void)captureOutput:(AVCapturePhotoOutput *)captureOutput
didFinishProcessingPhotoSampleBuffer:(CMSampleBufferRef)photoSampleBuffer
previewPhotoSampleBuffer:(CMSampleBufferRef)previewPhotoSampleBuffer
     resolvedSettings:(AVCaptureResolvedPhotoSettings *)resolvedSettings
      bracketSettings:(AVCaptureBracketedStillImageSettings *)bracketSettings
                error:(NSError *)error {
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(previewPhotoSampleBuffer);
    CIImage *ciImage = [CIImage imageWithCVImageBuffer:imageBuffer];
    UIImage *previewImage = [UIImage imageWithCIImage:ciImage];
    // do something...
}