AVCaptureDevice 曝光模式

Exposure Modes

AVCaptureExposureModeContinuousAutoExposure  ---自動調節曝光

AVCaptureExposureModeLocked  --使用當前曝光

下面是設置爲持續自動曝光的例子：

if ([currentDevice isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
    CGPoint exposurePoint = CGPointMake(0.5f, 0.5f); // 曝光點爲中心
    [currentDevice setExposurePointOfInterest:exposurePoint];
    [currentDevice setExposureMode:AVCaptureExposureModeContinuousAutoExposure];
}