晚上扫描会自动感光打开手电筒吗

[moselon]

晚上扫描会自动感光打开手电筒吗

[zhangkn]

这个很简单，可以自己监听代理方法。

具体是这样的：（brightnessValue 值代表光线强度，值越小代表光线越暗）

`
@Property (nonatomic, strong) AVCaptureVideoDataOutput *videoDataOutput;
// 创建摄像数据输出流，用于识别光线强弱
_videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];

/// MARK: Defines an interface for delegates of AVCaptureVideoDataOutput to receive captured video sample buffers and be notified of late sample buffers that were dropped.
//
/// MARK: 亮度变化

• (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
  CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL, sampleBuffer, kCMAttachmentMode_ShouldPropagate);
  NSDictionary *metadata = [[NSDictionary alloc] initWithDictionary:(__bridge NSDictionary *)metadataDict];
  CFRelease(metadataDict);
  NSDictionary *exifDictionary = [metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary];
  float brightness = [[exifDictionary objectForKey:(NSString *)kCGImagePropertyExifBrightnessValue] floatValue];
  if (brightness > 0) {
  // 光线明亮，隐藏按钮
  [self.maskView hideLightButton];
  } else {
  // 光线昏暗，显示按钮
  [self.maskView showLightButton];
  }

}
`