do snapshot during dragging?

Hello! I would like to ask is there any method to take a snap shot during dragging? I tried calling snapshot() in dispatch_after() but it seems the snapshots are performed after the dragging finish. Here is my code:

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(0.5 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
        snapshot("23NextUpSwippingUp")
    }
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(1 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
        snapshot("24NextUpSwippingUp")
    }
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(2 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
        snapshot("25NextUpSwippingUp")
    }

    /*swipe the screen on the next video's preview and expect it is removed*/
    app.coordinateWithNormalizedOffset(CGVector(dx: 0.75, dy: 0.5)).pressForDuration(0, thenDragToCoordinate: app.coordinateWithNormalizedOffset(CGVector(dx: 0.75, dy: 0.1))
    )

fastlane-old / snapshot

do snapshot during dragging? #457