Draggable UIView Swift 3 Xcode 8 ios app tutorial UItableview ,UICollectionview , UIbutton

The actual dragging takes place in the .Changed state. If there is a view selected, I store it’s center property. Then, I calculate how far the touch moved. You can use this as a threshold. Since I want to be able to configure whether the view can be dragged in the x or y direction (or both), I use two instance variables shouldDragX and shouldDragY. If these are true I set the center property of the selected view to the new location. This location has been “snapped” by a snap value. For example, if snapX is 25.0, the view will be dragged only in increments of 25.0.