Merge pull request #1 from zalando/invalidateDownloadingImagesOnReusa…

…bleImageViews invalidate downloading operations for imageViews when the image is set a...
JanGorman · Dec 19, 2014 · dc17ad3 · dc17ad3
2 parents ae22132 + 35bcfc2
commit dc17ad3
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Showing 4 changed files with 36 additions and 5 deletions.
diff --git a/Library/MapleBacon/MapleBacon/ImageDownloader.swift b/Library/MapleBacon/MapleBacon/ImageDownloader.swift
@@ -26,6 +26,7 @@ public class ImageDownloader: NSObject, NSURLSessionDownloadDelegate {
     private var task: NSURLSessionDownloadTask!
     private var progress: NSProgress?
     private var resumeData: NSData?
+    private var invalidated = false
 
     public convenience override init() {
         self.init(delegate: nil)
@@ -86,11 +87,15 @@ public class ImageDownloader: NSObject, NSURLSessionDownloadDelegate {
     public func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) {
         let newData = NSData(contentsOfURL: location)!
         let newImage = UIImage.imageWithData(newData)
-        let newImageInstance = ImageInstance(image: newImage, data: newData, state: .New, url: imageURL)
+        let newImageInstance = ImageInstance(image: newImage, data: newData, state: finishedState(), url: imageURL)
         completionHandler?(newImageInstance, nil)
         progress = nil
     }
 
+    public func finishedState() -> ImageInstanceState {
+        return invalidated ? .Invalidated : .New
+    }
+
     public func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
         if let error = error {
             println("API error: \(error), \(error.userInfo)")
@@ -103,10 +108,15 @@ public class ImageDownloader: NSObject, NSURLSessionDownloadDelegate {
         self.completionHandler!(nil, nil)
         startTask(image: request.URL)
     }
+
+    public func invalidateDownload() {
+        invalidated = true
+    }
+
 }
 
 public enum ImageInstanceState {
-    case New, Cached, Downloading
+    case New, Cached, Downloading, Invalidated
 }
 
 public struct ImageInstance {
@@ -121,4 +131,9 @@ public struct ImageInstance {
         self.url = url
         self.data = data
     }
+
+    public func isInvalidated() -> Bool {
+        return state == .Invalidated
+    }
+
 }
diff --git a/Library/MapleBacon/MapleBacon/ImageManager.swift b/Library/MapleBacon/MapleBacon/ImageManager.swift
@@ -5,6 +5,8 @@
 import Foundation
 import UIKit
 
+var ImageViewAssociatedObjectHandle: UInt8 = 0
+
 public class ImageManager: NSObject {
 
     lazy var downloadsInProgress = [NSURL: ImageDownloader]()
@@ -45,7 +47,7 @@ public class ImageManager: NSObject {
                                 storage.storeImage(newImage, data: imageData!, forKey: url.absoluteString!)
                             }
 
-                            completion(ImageInstance(image: newImage, state: .New, url: imageInstance?.url), nil)
+                            completion(ImageInstance(image: newImage, state: imageInstance!.state, url: imageInstance?.url), nil)
                         }
                     }
                 })
@@ -68,4 +70,13 @@ public class ImageManager: NSObject {
         return !downloadsInProgress.isEmpty
     }
 
+    public func invalidateDownloadForImageView(imageView: UIImageView) {
+        if let url = objc_getAssociatedObject(imageView, &ImageViewAssociatedObjectHandle) as? NSURL {
+            if let operation = downloadsInProgress[url] {
+                operation.invalidateDownload()
+            }
+        }
+
+    }
+
 }
diff --git a/Library/MapleBacon/MapleBacon/ImageViewExtension.swift b/Library/MapleBacon/MapleBacon/ImageViewExtension.swift
@@ -12,12 +12,17 @@ extension UIImageView {
     }
 
     public func setImageWithURL(url: NSURL, cacheScaled: Bool = false, completion: ImageDownloaderCompletion?) {
+        ImageManager.sharedManager.invalidateDownloadForImageView(self)
+        objc_setAssociatedObject(self, &ImageViewAssociatedObjectHandle, url, objc_AssociationPolicy(OBJC_ASSOCIATION_RETAIN_NONATOMIC))
+
         ImageManager.sharedManager.downloadImageAtURL(url, cacheScaled: cacheScaled, imageView: self, completion: {
             [weak self] (imageInstance: ImageInstance?, error: NSError?) -> Void in
 
             dispatch_async(dispatch_get_main_queue()) {
                 if let image = imageInstance?.image {
-                    self?.image = image
+                    if !imageInstance!.isInvalidated() {
+                        self?.image = image
+                    }
                 }
                 if let completion = completion {
                     completion(imageInstance, error)

diff --git a/Library/MapleBacon/MapleBacon/Info.plist b/Library/MapleBacon/MapleBacon/Info.plist
@@ -15,7 +15,7 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>1.0</string>
+	<string>1.0.1</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>