iOS打开相机的闪光灯

- (IBAction)openFlash:(id)sender {
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if ([device hasTorch] && [device hasFlash]) {
        [device lockForConfiguration:nil];
        if (hasClosed) {
            [device setTorchMode:AVCaptureTorchModeOn];
        } else {
            [device setTorchMode:AVCaptureTorchModeOff];
        }
        [device unlockForConfiguration];
    }
}