Add unlimited undo functionality

Author: arneson

KSSwipeStack.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'KSSwipeStack'
-  s.version          = '0.3.1'
+  s.version          = '0.4.0'
   s.summary          = 'A Swift card swiping library created by Kicksort Consulting AB'
 
 # This description is used to generate tags and improve search results.
@@ -28,7 +28,7 @@ DOCS: https://github.com/Kicksort/KSSwipeStack
                        DESC
 
   s.homepage         = 'https://github.com/Kicksort/KSSwipeStack'
-  # s.screenshots     = 'www.example.com/screenshots_1', 'www.example.com/screenshots_2'
+  s.screenshots     = 'https://camo.githubusercontent.com/0c98618dc067d31bf4a0126d408082f3911d4181/68747470733a2f2f6d656469612e67697068792e636f6d2f6d656469612f7738426e6d736a634a79464b552f67697068792e676966'
   s.license          = { :type => 'MIT', :file => 'LICENSE' }
   s.author           = { 'Simon Arneson' => 'arneson@kicksort.se' }
   s.source           = { :git => 'https://github.com/kicksort/KSSwipeStack.git', :tag => s.version.to_s }

KSSwipeStack/Classes/SwipeView.swift

@@ -9,6 +9,12 @@
 import UIKit
 import RxSwift
 
+
+struct SwipeHistoryItem {
+    let data: SwipableData
+    let origin: CGPoint
+}
+
 /// Represents a swipable view to be rendered in the swipe stack. 
 /// The visual representation of a SwipeData object.
 public class SwipeView: UIView {
@@ -18,7 +24,7 @@ public class SwipeView: UIView {
 
     fileprivate var dataset: [SwipableData] = []
     fileprivate var renderedCards: [SwipableView] = []
-    fileprivate var previousCard: SwipableView?
+    fileprivate var swipeHistory: [SwipeHistoryItem] = []
     fileprivate var options = SwipeOptions()
 
     fileprivate var swipeDelegate: SwipeDelegate?
@@ -88,6 +94,21 @@ public class SwipeView: UIView {
         bringSubview(toFront: renderedCard)
     }
 
+    /**
+     Adds a card to the top of the stack and calls notifyDatasetUpdated to make sure it is rendered if needed.
+     - parameter data: The data the new card represents.
+     */
+    public func addCardToTop(_ data: SwipableData, from origin: CGPoint) {
+        let cardFrame = CGRect(x: 0, y: 0, width: frame.width, height: frame.height)
+        let renderedCard = renderCard(data.getView(with: cardFrame))
+        renderedCard.frame.origin = origin
+        renderedCards.insert(renderedCard, at: 0)
+        addSubview(renderedCard)
+        swipeHelper.transformCard(renderedCard)
+        bringSubview(toFront: renderedCard)
+        snapBack()
+    }
+    
     /**
      Get swipe events generated by the SwipeView
      - returns: RxObservable firing once for each swipe
@@ -112,6 +133,17 @@ public class SwipeView: UIView {
         return needsRefill()
     }
 
+    // Undoes last swipe
+    public func undoSwipe() {
+        guard options.allowUndo else {
+            return
+        }
+        
+        if let cardToUndo = swipeHistory.popLast() {
+            addCardToTop(cardToUndo.data, from: cardToUndo.origin)
+        }
+    }
+    
     fileprivate func setupSwipeCards() {
 
     }
@@ -267,8 +299,10 @@ public class SwipeView: UIView {
             // TODO
             return
         }
-        
-        previousCard = card.isUndoable() ? card : nil
+    
+        if card.isUndoable(), let data = card.getData() {
+            swipeHistory.append(SwipeHistoryItem(data: data, origin: card.frame.origin))
+        }
 
         dismissCard(direction: direction, gesture: gesture, completion: { [weak self] in
             let swipe = Swipe(direction: direction, data: card.getData())