Merge branch 'Part5' of https://github.com/jquave/Swift-Tutorial

Author: jquave

TestSwift/SearchResultsViewController.swift

@@ -15,6 +15,7 @@ class SearchResultsViewController: UIViewController, UITableViewDataSource, UITa
     var api: APIController = APIController()
     @IBOutlet var appsTableView : UITableView
     var tableData: NSArray = NSArray()
+    var imageCache = NSMutableArray()
 
     override func viewDidLoad() {
         super.viewDidLoad()
@@ -38,17 +39,52 @@ class SearchResultsViewController: UIViewController, UITableViewDataSource, UITa
         var rowData: NSDictionary = self.tableData[indexPath.row] as NSDictionary
 
         cell.text = rowData["trackName"] as String
-        
-        // Grab the artworkUrl60 key to get an image URL for the app's thumbnail
-        var urlString: NSString = rowData["artworkUrl60"] as NSString
-        var imgURL: NSURL = NSURL(string: urlString)
-        
-        // Download an NSData representation of the image at the URL
-        var imgData: NSData = NSData(contentsOfURL: imgURL)
-        cell.image = UIImage(data: imgData)
+        cell.image = UIImage(named: "Icon76")
+
 
         // Get the formatted price string for display in the subtitle
         var formattedPrice: NSString = rowData["formattedPrice"] as NSString
+        
+        dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
+            // Jump in to a background thread to get the image for this item
+            
+            // Grab the artworkUrl60 key to get an image URL for the app's thumbnail
+            var urlString: NSString = rowData["artworkUrl60"] as NSString
+            
+            // Check our image cache for the existing key. This is just a dictionary of UIImages
+            var image: UIImage? = self.imageCache.valueForKey(urlString) as? UIImage
+
+            if( !image? ) {
+                // If the image does not exist, we need to download it
+                var imgURL: NSURL = NSURL(string: urlString)
+                
+                println("Download the image \(imgURL)")
+                // Download an NSData representation of the image at the URL
+                var imgData: NSData = NSData(contentsOfURL: imgURL)
+                image = UIImage(data: imgData)
+                
+                // Store the image in to our cache
+                self.imageCache.setValue(image, forKey: urlString)
+                
+                println("Image downloaded")
+            }
+            dispatch_async(dispatch_get_main_queue()) {
+                // Back on the main thread, let's set the image view of the cell to use our amazing new image
+                // First, we need to make sure the cell hasn't gone off the screen, or worse, been re-used
+                // Validate the cell is still available by using cellForRowAtIndexPath
+                var sCell: UITableViewCell? = tableView.cellForRowAtIndexPath(indexPath)
+                
+                // If the cell exists, we're good and we can update it with this image
+                if sCell? {
+                    let pCell: UITableViewCell = sCell!
+                    pCell.image = image
+                    println("set image")
+                }
+            }
+            
+        })
+
+        tableView.indexPathForCell(cell)
 
         cell.detailTextLabel.text = formattedPrice