fix history cell image caching

@@ -15,6 +15,24 @@ class AnalysisItemViewCell: UITableViewCell {
     @IBOutlet weak var priceLabel: UILabel!
     @IBOutlet weak var subtitleLabel: UILabel!
 
+    var postImageURL: String? {
+        didSet {
+            if let url = postImageURL {
+                self.itemImage.image = UIImage() // UIImage(named: "loading")
+
+                UIImage.loadImageUsingCacheWithUrlString(url) { image in
+                    // set the image only when we are still displaying the content for the image we finished downloading
+                    if url == self.postImageURL {
+                        self.itemImage.image = image
+                    }
+                }
+            }
+            else {
+                self.itemImage.image = nil
+            }
+        }
+    }
+    
     // lifecycle
     override func awakeFromNib() {
         super.awakeFromNib()
@@ -42,7 +60,8 @@ extension AnalysisItemViewCell {
 
         for merchant in merchantList {
             if (merchant._uuid == item._merchant_uuid) {
-               itemImage.load(link: merchant._img_preview, placeholder: UIImage(), cache: URLCache())
+            //    itemImage.load(link: merchant._img_preview, placeholder: UIImage(), cache: URLCache())
+                self.postImageURL = merchant._img_preview
                titleLabel.text = merchant._admin_name
                break;
            }
@@ -76,7 +95,8 @@ extension AnalysisItemViewCell {
         
         for merchant in merchantList {
             if (merchant._uuid == couponSetData?.merchant_uuid) {
-                itemImage.load(link: merchant._img_preview, placeholder: UIImage(), cache: URLCache())
+                // itemImage.load(link: merchant._img_preview, placeholder: UIImage(), cache: URLCache())
+                self.postImageURL = merchant._img_preview
                 titleLabel.text = merchant._admin_name
                 break;
             }