AVCaptureSession is blocking UI on main thread in ios8

In our application, it is used AVCaptureSession

to scan qr / barcode. There is a simple close button that has stopped responding in iOS 8.

It looks like the output buffer is overloading the main UI thread.

It looks like the current output is on the main thread:

[captureOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];

      

        
        
        
      

    

Should I run all this on a separate thread? Current attempts to start a background thread have failed.