Insert AVCaptureVideoPreviewLayer at the bottom.
Insert AVCaptureVideoPreviewLayer at the bottom.

Make it possible to add views on the previewView property. Especially useful when it's a full screen scanner.

jaybowong/MTBBarcodeScanner,heefan/MTBBarcodeScanner,JeremyPacker/MTBBarcodeScanner,mikebuss/MTBBarcodeScanner,mikebuss/MTBBarcodeScanner,cnbin/MTBBarcodeScanner,mikebuss/MTBBarcodeScanner,Kalvar/MTBBarcodeScanner