UIImagePickerController Custom Overlay Black Screen issue while using Video trimming controller

[inx123]

Hello Everyone ,

I have problem while opening camera in recording mode using UIImagePicker Controller with custom overlay and it should open first time properly .But when i push to next view controller and return back again to open camera at that time camera displays black screen for few time.

The Logic in the inside view controller is for VideoTrimming . For video trimming i have used "SAVideoRangeSlider" controll. SAVideoRange Silder perform task to get all thumbnail images from video which i have assign . It uses AVAsset image generator class provided by apple to get image frames from videos and it runs in background using its handler method.

Handler Method ::
[self.imageGenerator generateCGImagesAsynchronouslyForTimes:times
completionHandler:^(CMTime requestedTime, CGImageRef image, CMTime actualTime,
AVAssetImageGeneratorResult result, NSError *error) {

                                                                  }

I have nilling all the objects related to image generator class when i came back to Camera screen. still issues of black screen occur while opening camera.

This issue occur in ios7 but not in ios6.

Can anyone have any idea about this ...Please relply me ASAP.