This is what I tackled just a few days back. What I did was basically remove the arrow and provided a source rect myself. The source, of course, had its Y position altered to give it a popover effect without the arrow. Try it, worked like a charm for me.
yourPopoverPresentationController!.permittedArrowDirections = UIPopoverArrowDirection.init(rawValue: 0)
let aView = //Source View that you would provide for the source rect
yourPopoverPresentationController!.sourceView = aView
let position = CGRectMake(aView.bounds.origin.x, aView.bounds.origin.y + 125, aView.bounds.size.width, aView.bounds.size.height)
yourPopoverPresentationController!.sourceRect = position
This resulted in the following effect which was what I required.
