Merge pull request #8 from misterwindupbird/ondemand

Icons are now only downloaded on demand (when the PhotoAppLink interface is first presented). Previously all icons were downloaded on app start, even if users never used the PhotoAppLink feature.
The library now requires iOS 4 or later.

PhotoAppLink/PALAppInfo.h

@@ -33,7 +33,6 @@
     NSString*   appleID;
     NSString*   platform;
     BOOL        freeApp;
-    UIImage*    thumbnail;
     NSURL*      thumbnailURL;
 }
 
@@ -63,8 +62,6 @@
 @property (nonatomic, copy) NSString *platform;
 // whether the app is free or paid
 @property (nonatomic) BOOL freeApp;
-// The image thumbnail (with appropriate scale for the device)
-@property (nonatomic, readonly) UIImage* thumbnail;
 // URL to thumbnail image
 @property (nonatomic, readonly) NSURL* thumbnailURL;
 

PhotoAppLink/PALAppInfo.m

@@ -11,7 +11,7 @@ @implementation PALAppInfo
 @synthesize name, scheme, appDescription, bundleID, appleID;
 @synthesize platform, freeApp;
 @synthesize thumbnailURL, installed, liveOnAppStore, canSend, canReceive;
-@synthesize thumbnail;
+
 
 - (id)initWithPropertyDict:(NSDictionary*)properties {
     self = [super init];
@@ -45,7 +45,6 @@ - (void) dealloc
 	[bundleID release];
     [appleID release];
 	[thumbnailURL release];
-    [thumbnail release];
     [platform release];
     [super dealloc];
 }
@@ -59,13 +58,5 @@ - (NSURL*)appStoreLink
     return [NSURL URLWithString:affiliateLink];
 }
 
-- (UIImage*)thumbnail
-{
-    if (thumbnail) return thumbnail;
-    thumbnail = [[[PALManager sharedPALManager] cachedIconForApp:self] retain];
-    if (thumbnail) return thumbnail;
-    else return [UIImage imageNamed:GENERIC_APP_ICON];
-}
-
 @end
 

PhotoAppLink/PALConfig.h

@@ -9,12 +9,6 @@
 #define DEBUG_PLIST_URL     @"http://www.photoapplink.com/photoapplink_debug.plist"
 
 
-// If you are not using app icons to display the list of supported apps in your UI 
-// (for example because you only use the action sheet displaying the app names)
-// you can set this to NO to disable downloading of these app icons
-#define USING_APP_ICONS     YES
-
-
 // Substitute your own Linkshare Site ID here if you like.
 // This Linkshare ID is used to create affiliate links to 
 // supported apps on the App Store
@@ -24,3 +18,9 @@
 // The image to use for apps with missing icons
 // The file has to be included in the app bundle
 #define GENERIC_APP_ICON    @"PAL_unknown_app_icon.png"
+
+
+// The placeholder image to show while the image
+// is loading.  It will be replaced with the actual
+// app icon or the generic icon.
+#define PLACEHOLDER_APP_ICON @"PAL_default_app_icon.png"

PhotoAppLink/PALManager.h

@@ -22,12 +22,11 @@
 
 #import <Foundation/Foundation.h>
 
-@class PALAppInfo; 
+typedef void(^PALImageRequestHandler)(UIImage* image, NSError* error);
 
-@interface PALManager : NSObject <UIActionSheetDelegate> {
-    NSArray* supportedApps;
-    UIImage* imageToSend;
-}
+@class PALAppInfo;
+
+@interface PALManager : NSObject <UIActionSheetDelegate, NSURLConnectionDelegate>
 
 // the PALAppInfo objects of the photo editing apps that are installed on the user's device
 // and support receiving images via the photo app link protocol
@@ -61,4 +60,6 @@
 
 - (UIImage*)cachedIconForApp:(PALAppInfo*)app;
 
+- (void)asyncIconForApp:(PALAppInfo*)app withCompletion:(PALImageRequestHandler)completion;
+
 @end

PhotoAppLink/PALManager.m

@@ -30,6 +30,11 @@
 static NSString *const LAUNCH_DATE_KEY = @"launchDate";
 static NSString *const SUPPORTED_APPS_PLIST_KEY = @"supportedApps";
 static NSString *const PASTEBOARD_NAME = @"com.photoapplink.pasteboard";
+static NSString *const RECEIVED_DATA_KEY = @"ReceivedDataKey";
+static NSString *const COMPLETION_BLOCK_KEY = @"CompletionBlockKey";
+static NSString *const APPINFO_KEY = @"AppInfoKey";
+
+static const int kImageDownloadErrorCode = 2001;
 
 #ifdef DEBUG 
 const int MINIMUM_SECS_BETWEEN_UPDATES = 0; 
@@ -38,17 +43,39 @@
 const int MINIMUM_SECS_BETWEEN_UPDATES = 4 * 60 * 60; 
 #endif
 
-@interface PALManager() 
+@interface PALManager()
+{
+    CFMutableDictionaryRef connectionToData;
+    NSMutableDictionary*   loadedIcons;
+}
 @property (nonatomic,copy) NSArray *supportedApps;
 @property (nonatomic,retain) UIImage *imageToSend;
-- (void)downloadAndCacheIconsForAllApps;
 @end
 
 @implementation PALManager
 
 @synthesize supportedApps;
 @synthesize imageToSend;
 
+// Since the PALManager class is a singleton, the init method will only ever be called once
+- (id)init
+{
+    self = [super init];
+    if (self) {
+        loadedIcons = [NSMutableDictionary new];
+
+        // This will map NSURLConnections to downloaded data using the connection as the key.  We can't use NSMutableDictionary
+        // because NSURLConnection does not support copy.
+        connectionToData = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
+
+        [[NSNotificationCenter defaultCenter] addObserver:self
+                                                 selector:@selector(receivedMemoryWarning)
+                                                     name:UIApplicationDidReceiveMemoryWarningNotification
+                                                   object:nil];
+        [self createAppIconCacheDirectory];
+    }
+    return self;
+}
 
 // trigger background update of the list of supported apps
 // This update is only performed once every few days
@@ -64,10 +91,6 @@ - (void)updateSupportedAppsInBackground
     if (!lastUpdateDate || secondsSinceLastUpdate > MINIMUM_SECS_BETWEEN_UPDATES) {
         [self performSelectorInBackground:@selector(requestSupportedAppURLSchemesUpdate) withObject:nil];            
     }
-    else if (USING_APP_ICONS){
-        // still check for any missing app icons and download them
-        [self performSelectorInBackground:@selector(downloadAndCacheIconsForAllApps) withObject:nil];            
-    }
 }
 
 
@@ -125,10 +148,6 @@ - (void)requestSupportedAppURLSchemesUpdate
             [userPrefs synchronize];
             if (plist) CFRelease(plist);
         }
-        if (USING_APP_ICONS) {
-            // download app icons for all apps in the list of supported apps
-            [self downloadAndCacheIconsForAllApps];
-        }
     }
     @catch (NSException * e) {
         NSLog(@"Caught exception in -[PALManager requestSupportedAppURLSchemesUpdate]: %@", e);
@@ -237,12 +256,6 @@ - (void)createAppIconCacheDirectory
     }
 }
 
-- (void)clearAppIconCache
-{
-    [[NSFileManager defaultManager] removeItemAtPath:[self appIconCacheDirectory] error:nil];
-    [self createAppIconCacheDirectory];
-}
-
 - (NSString*)cachedIconPathForApp:(PALAppInfo*)app
 {
     NSString* lastPathComponent = [[[app.thumbnailURL path] componentsSeparatedByString:@"/"] lastObject];
@@ -253,55 +266,110 @@ - (NSString*)cachedIconPathForApp:(PALAppInfo*)app
 
 - (UIImage*)cachedIconForApp:(PALAppInfo*)app
 {
-    UIImage* icon = [UIImage imageWithContentsOfFile:[self cachedIconPathForApp:app]];
+    UIImage* icon = [loadedIcons objectForKey:app.thumbnailURL];
+
+    if (icon == nil) {
+        icon = [UIImage imageWithContentsOfFile:[self cachedIconPathForApp:app]];
+
+        // if we pulled an icons from the cache, keep it in memory
+        if (icon != nil) {
+            [loadedIcons setObject:icon forKey:app.thumbnailURL];
+        }
+    }
     if (icon == nil) return nil;
+    return [self screenScaleImageForImage:icon];
+}
+
+- (UIImage*)screenScaleImageForImage:(UIImage*)image
+{
     BOOL isRetina = [[UIScreen mainScreen] respondsToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2.0f;
-    if (!isRetina || [icon scale] > 1.0) return icon;
+    if (!isRetina || [image scale] > 1.0) return image;
     else {
         // need to create image with appropriate scale
         float scale = [[UIScreen mainScreen] scale];
-        UIImageOrientation orientation = [icon imageOrientation];
-        UIImage* retinaIcon = [UIImage imageWithCGImage:icon.CGImage scale:scale orientation:orientation];
-        return retinaIcon;
+        UIImageOrientation orientation = [image imageOrientation];
+        UIImage* retinaImage = [UIImage imageWithCGImage:image.CGImage scale:scale orientation:orientation];
+        return retinaImage;
     }
 }
 
-- (void)downloadAndCacheIconsForAllApps
+
+- (void)asyncIconForApp:(PALAppInfo *)appInfo
+         withCompletion:(PALImageRequestHandler)completion
 {
-    NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
-    @try {
-        // ensure that the cache directory exists
-        [self createAppIconCacheDirectory];
-
-        NSUserDefaults* userPrefs = [NSUserDefaults standardUserDefaults];
-        NSDictionary* plistDict = [userPrefs dictionaryForKey:PLIST_DICT_USERPREF_KEY];    
-        NSArray* plistApps = [plistDict objectForKey:SUPPORTED_APPS_PLIST_KEY];
-        if (plistApps == nil) return;
+    NSURLRequest* request = [[NSURLRequest alloc] initWithURL:appInfo.thumbnailURL
+                                                  cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
+                                              timeoutInterval:60.0];
+    NSURLConnection* connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO];
+    [connection scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
+    [connection start];
+    [request release];
+
+    NSMutableDictionary* connectionInfo = [NSMutableDictionary dictionaryWithObjectsAndKeys:[NSMutableData data], RECEIVED_DATA_KEY,
+                                           [[completion copy] autorelease], COMPLETION_BLOCK_KEY,
+                                           appInfo, APPINFO_KEY, nil];
+    CFDictionaryAddValue(connectionToData, connection, connectionInfo);
+}
+
+
+- (void)receivedMemoryWarning
+{
+    if (loadedIcons != nil) [loadedIcons removeAllObjects];
+}
+
+
+
+#pragma mark -
+#pragma mark NSURLConnectionDelegate
+
+- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
+{
+    NSMutableDictionary* connectionInfo = CFDictionaryGetValue(connectionToData, connection);
+    [[connectionInfo objectForKey:RECEIVED_DATA_KEY] appendData:data];
+}
+
+
+- (void)connectionDidFinishLoading:(NSURLConnection *)connection
+{
+    NSMutableDictionary* connectionInfo = CFDictionaryGetValue(connectionToData, connection);
+    PALImageRequestHandler completion = [connectionInfo objectForKey:COMPLETION_BLOCK_KEY];
+    NSData* imageData = [connectionInfo objectForKey:RECEIVED_DATA_KEY];
+    PALAppInfo* appInfo = [connectionInfo objectForKey:APPINFO_KEY];
+
+    UIImage* image = [UIImage imageWithData:imageData];
+
+    if (image == nil) {
+        NSError* downloadError = [NSError errorWithDomain:@"com.photoapplink" code:kImageDownloadErrorCode userInfo:nil];
+        completion(nil, downloadError);
+    }
+    else {
+        image = [self screenScaleImageForImage:image];
+        NSString* cachedIconPath = [self cachedIconPathForApp:appInfo];
+        [imageData writeToFile:cachedIconPath atomically:YES];
 
-        for (NSDictionary* plistAppInfo in plistApps) {
-            PALAppInfo* appInfo = [[PALAppInfo alloc] initWithPropertyDict:plistAppInfo];
-            NSString* cachedIconPath = [self cachedIconPathForApp:appInfo];
-            if (![[NSFileManager defaultManager] isReadableFileAtPath:cachedIconPath]) {
-                NSData* imageData = [[NSData alloc] initWithContentsOfURL:appInfo.thumbnailURL];
-                // verify that the data is actually an image
-                UIImage* image = [[UIImage alloc] initWithData:imageData];
-                if (image != nil) {
-                    [imageData writeToFile:cachedIconPath atomically:YES];                
-                }
-                [imageData release];
-                [image release];
-            }
-            [appInfo release];
+        if (loadedIcons != nil) {
+            [loadedIcons setObject:image forKey:appInfo.thumbnailURL];
         }
-    }
-    @catch (NSException * e) {
-        NSLog(@"Caught exception in -[PALManager requestSupportedAppURLSchemesUpdate]: %@", e);
+        completion(image, nil);
     }
 
-    [pool release];
+    CFDictionaryRemoveValue(connectionToData, connection);
+    [connection release];
 }
 
 
+- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
+{
+    NSMutableDictionary* connectionInfo;
+    connectionInfo = CFDictionaryGetValue(connectionToData, connection);
+    PALImageRequestHandler completion = [connectionInfo objectForKey:COMPLETION_BLOCK_KEY];
+
+    completion(nil, error);
+
+    CFDictionaryRemoveValue(connectionToData, connection);
+    [connection release];
+}
+
 #pragma mark -
 #pragma mark Action Sheet
 

PhotoAppLink/PALMoreAppsTableCellView.h

@@ -24,6 +24,7 @@
 
 @interface PALMoreAppsTableCellView : UIView {
     PALAppInfo* appInfo;
+    UIImage*    icon;
 }
 
 @property (nonatomic, retain) PALAppInfo *appInfo;