From 7ab4e36a0bf962c5db4d11bf46b571d5a1a1cb52 Mon Sep 17 00:00:00 2001
From: Neil Robichaud <neil.robichaud@hotmail.com>
Date: Tue, 7 Mar 2017 11:02:08 -0500
Subject: [PATCH] added comments to your files

---
 .DS_Store                                | Bin 0 -> 8196 bytes
 Dropit/.DS_Store                         | Bin 0 -> 6148 bytes
 Dropit/Dropit/.DS_Store                  | Bin 0 -> 6148 bytes
 Dropit/Dropit/DropitBehavior.swift       |  11 +++--
 Dropit/Dropit/DropitViewController.swift |  54 +++++++++++++----------
 5 files changed, 37 insertions(+), 28 deletions(-)
 create mode 100644 .DS_Store
 create mode 100644 Dropit/.DS_Store
 create mode 100644 Dropit/Dropit/.DS_Store

diff --git a/.DS_Store b/.DS_Store
new file mode 100644
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diff --git a/Dropit/.DS_Store b/Dropit/.DS_Store
new file mode 100644
index 0000000000000000000000000000000000000000..ea5458920a529fef6d9b13c94005d7f1409c491e
GIT binary patch
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diff --git a/Dropit/Dropit/.DS_Store b/Dropit/Dropit/.DS_Store
new file mode 100644
index 0000000000000000000000000000000000000000..30d6ce62d52282b09012d5e36a31489575e59ab2
GIT binary patch
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HcmV?d00001

diff --git a/Dropit/Dropit/DropitBehavior.swift b/Dropit/Dropit/DropitBehavior.swift
index 05d3c9b..89ebcd4 100644
--- a/Dropit/Dropit/DropitBehavior.swift
+++ b/Dropit/Dropit/DropitBehavior.swift
@@ -12,6 +12,7 @@ class DropitBehavior: UIDynamicBehavior
 {
     let gravity = UIGravityBehavior()
     
+    //create UIDynamicBehaviors after initial load
     lazy var collider: UICollisionBehavior = {
         let lazilyCreatedCollider = UICollisionBehavior()
         lazilyCreatedCollider.translatesReferenceBoundsIntoBoundary = true
@@ -24,26 +25,28 @@ class DropitBehavior: UIDynamicBehavior
         lazilyCreatedDropBehavior.elasticity = 0.75
         return lazilyCreatedDropBehavior
     }()
-    
+    //override initializer
     override init() {
+        //always call superclass method when overriding
         super.init()
+        //add the UIDynamicBehavior
         addChildBehavior(gravity)
         addChildBehavior(collider)
         addChildBehavior(dropBehavior)
     }
-    
+    //remove old barrier and add new barrier
     func addBarrier(path: UIBezierPath, named name: String) {
         collider.removeBoundaryWithIdentifier(name)
         collider.addBoundaryWithIdentifier(name, forPath: path)
     }
-    
+    //add a new drop to the scene
     func addDrop(drop: UIView) {
         dynamicAnimator?.referenceView?.addSubview(drop)
         gravity.addItem(drop)
         collider.addItem(drop)
         dropBehavior.addItem(drop)
     }
-    
+    //remove the passed in drop from the scene
     func removeDrop(drop: UIView) {
         gravity.removeItem(drop)
         collider.removeItem(drop)
diff --git a/Dropit/Dropit/DropitViewController.swift b/Dropit/Dropit/DropitViewController.swift
index 5907466..f7a559e 100644
--- a/Dropit/Dropit/DropitViewController.swift
+++ b/Dropit/Dropit/DropitViewController.swift
@@ -12,9 +12,11 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
 {
     // MARK: - Outlets
 
-    @IBOutlet weak var gameView: BezierPathsView!
+    @IBOutlet weak var gameView: BezierPathsView!   //gameView is the main area that the game is displayed on
     
     // MARK: - Animation
+    
+    /*animator cannot be created at start time, must be initialized lazily */
 
     lazy var animator: UIDynamicAnimator = {
         let lazilyCreatedDynamicAnimator = UIDynamicAnimator(referenceView: self.gameView)
@@ -25,18 +27,19 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
     let dropitBehavior = DropitBehavior()
     
     var attachment: UIAttachmentBehavior? {
+        // setting the UIAttachmentBehavior removes the previous instance
         willSet {
             animator.removeBehavior(attachment)
             gameView.setPath(nil, named: PathNames.Attachment)
         }
         didSet {
-            if attachment != nil {
-                animator.addBehavior(attachment)
-                attachment?.action = { [unowned self] in
+            if attachment != nil { //check against empty optional, otherwise program could crash
+                animator.addBehavior(attachment) //add the attachment to the animator
+                attachment?.action = { [unowned self] in //prevent reference cycle by declaring unowned self
                     if let attachedView = self.attachment?.items.first as? UIView {
                         let path = UIBezierPath()
                         path.moveToPoint(self.attachment!.anchorPoint)
-                        path.addLineToPoint(attachedView.center)
+                        path.addLineToPoint(attachedView.center)    //draws a line between the object and its anchorPoint
                         self.gameView.setPath(path, named: PathNames.Attachment)
                     }
                 }
@@ -45,7 +48,7 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
     }
     
     // MARK: - View Controller Lifecycle
-    
+    /* upon view loading, the animator adds the behaviour */
     override func viewDidLoad() {
         super.viewDidLoad()
         animator.addBehavior(dropitBehavior)
@@ -54,9 +57,10 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
     // creates a circular barrier in the center of the gameView
     // the barrier is currently sized to be the same as the size of a drop
     
-    override func viewDidLayoutSubviews() {
-        super.viewDidLayoutSubviews()
+    override func viewDidLayoutSubviews() { //called after view loading stage
+        super.viewDidLayoutSubviews()       //must call function of superclass when overriding
         let barrierSize = dropSize
+        //origin point is the bottom left corner of barrier
         let barrierOrigin = CGPoint(x: gameView.bounds.midX-barrierSize.width/2, y: gameView.bounds.midY-barrierSize.height/2)
         let path = UIBezierPath(ovalInRect: CGRect(origin: barrierOrigin, size: barrierSize))
         dropitBehavior.addBarrier(path, named: PathNames.MiddleBarrier)
@@ -64,29 +68,30 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
     }
     
     // MARK: - UIDynamicAnimatorDelegate
-
+    //will remove rows whenever all drops are stationary
     func dynamicAnimatorDidPause(animator: UIDynamicAnimator) {
         removeCompletedRow()
     }
     
     // MARK: - Gestures
-
+    //outlet that connects a tap gesture to the drop() function
     @IBAction func drop(sender: UITapGestureRecognizer) {
         drop()
     }
-    
+    //when a user makes a pan gesture grab the drop
     @IBAction func grabDrop(sender: UIPanGestureRecognizer) {
-        let gesturePoint = sender.locationInView(gameView)
+        let gesturePoint = sender.locationInView(gameView)  //the original point of the drag motion
+        
         
         switch sender.state {
-        case .Began:
+        case .Began:    //add a behaviour that anchors the drop to the gesture point
             if let viewToAttachTo = lastDroppedView {
                 attachment = UIAttachmentBehavior(item: viewToAttachTo, attachedToAnchor: gesturePoint)
                 lastDroppedView = nil
             }
-        case .Changed:
+        case .Changed:  //move the anchor to the new gesturepoint
             attachment?.anchorPoint = gesturePoint
-        case .Ended:
+        case .Ended:    //remove the attachment
             attachment = nil
         default: break
         }
@@ -94,14 +99,14 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
     
     // MARK: - Dropping
 
-    var dropsPerRow = 10
+    var dropsPerRow = 10    //determines the width of each drop
     
     var dropSize: CGSize {
         let size = gameView.bounds.size.width / CGFloat(dropsPerRow)
-        return CGSize(width: size, height: size)
+        return CGSize(width: size, height: size)    //drops are squares
     }
     
-    var lastDroppedView: UIView?
+    var lastDroppedView: UIView?    //keep track of the last drop for anchoring
     
     func drop() {
         var frame = CGRect(origin: CGPointZero, size: dropSize)
@@ -120,7 +125,7 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
     // in the end, does nothing more than call removeDrop() in DropitBehavior
 
     func removeCompletedRow()
-    {
+    {   //keep track of all the drops we are removing
         var dropsToRemove = [UIView]()
         var dropFrame = CGRect(x: 0, y: gameView.frame.maxY, width: dropSize.width, height: dropSize.height)
         
@@ -129,10 +134,11 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
             dropFrame.origin.x = 0
             var dropsFound = [UIView]()
             var rowIsComplete = true
+            //finds all the drop along the bottom row using a hit test
             for _ in 0 ..< dropsPerRow {
                 if let hitView = gameView.hitTest(CGPoint(x: dropFrame.midX, y: dropFrame.midY), withEvent: nil) {
                     if hitView.superview == gameView {
-                        dropsFound.append(hitView)
+                        dropsFound.append(hitView)  //if hittest is successful, add the drop to the list for removal
                     } else {
                         rowIsComplete = false
                     }
@@ -142,7 +148,7 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
             if rowIsComplete {
                 dropsToRemove += dropsFound
             }
-        } while dropsToRemove.count == 0 && dropFrame.origin.y > 0
+        } while dropsToRemove.count == 0 && dropFrame.origin.y > 0  //remove all rows above the bottom of the screen
         
         for drop in dropsToRemove {
             dropitBehavior.removeDrop(drop)
@@ -150,7 +156,7 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
     }
     
     // MARK: - Constants
-
+    //good programming practice to use structs rather than strings
     struct PathNames {
         static let MiddleBarrier = "Middle Barrier"
         static let Attachment = "Attachment"
@@ -158,13 +164,13 @@ class DropitViewController: UIViewController, UIDynamicAnimatorDelegate
 }
 
 // MARK: - Extensions
-
+//allows easy access to a random CGFloat
 private extension CGFloat {
     static func random(max: Int) -> CGFloat {
         return CGFloat(arc4random() % UInt32(max))
     }
 }
-
+//allows easy access to several basic UIColors
 private extension UIColor {
     class var random: UIColor {
         switch arc4random()%5 {