AVCaptureMovieFileOutput - no active/enabled connections

Question

I am trying to record video in my iPhone app using AVFoundation. But whenever I click the Record button app crashes with this message

-[AVCaptureMovieFile

Answer 1

Because currently you don't have an active connection to record video to file.
Check connection active status before recording to output file:

AVCaptureConnection *c = [self.movieOutput connectionWithMediaType:AVMediaTypeVideo];
if (c.active) {
  //connection is active
} else {
  //connection is not active
  //try to change self.captureSession.sessionPreset,
  //or change videoDevice.activeFormat
}

If connection is not active, try to change captureSession.sessionPreset or videoDevice.activeFormat.
Repeat until you have set a valid format (that means c.active == YES). Then you can record video to output file.