Update the downloader token's property to match the comments

SDWebImage/SDWebImageDownloader.h

@@ -92,14 +92,14 @@ typedef SDHTTPHeadersDictionary * _Nullable (^SDWebImageDownloaderHeadersFilterB
 @interface SDWebImageDownloadToken : NSObject <SDWebImageOperation>
 
 /**
- The download's URL. This should be readonly and you should not modify
+ Cancel the current download.
  */
-@property (nonatomic, strong, nullable) NSURL *url;
+- (void)cancel;
+
 /**
- The cancel token taken from `addHandlersForProgress:completed`. This should be readonly and you should not modify
- @note use `-[SDWebImageDownloadToken cancel]` to cancel the token
+ The download's URL.
  */
-@property (nonatomic, strong, nullable) id downloadOperationCancelToken;
+@property (nonatomic, strong, nullable, readonly) NSURL *url;
 
 @end
 
@@ -139,7 +139,7 @@ typedef SDHTTPHeadersDictionary * _Nullable (^SDWebImageDownloaderHeadersFilterB
 @property (nonatomic, assign, readonly) NSUInteger currentDownloadCount;
 
 /**
- *  Returns the global shared downloader instance. Which use the `SDWebImageDownloaderConfig.defaultDownloaderConfiguration` config.
+ *  Returns the global shared downloader instance. Which use the `SDWebImageDownloaderConfig.defaultDownloaderConfig` config.
  */
 @property (nonatomic, class, readonly, nonnull) SDWebImageDownloader *sharedDownloader;
 

SDWebImage/SDWebImageDownloader.m

@@ -15,20 +15,10 @@
 
 @interface SDWebImageDownloadToken ()
 
+@property (nonatomic, strong, nullable, readwrite) NSURL *url;
+@property (nonatomic, strong, nullable, readwrite) id downloadOperationCancelToken;
 @property (nonatomic, weak, nullable) NSOperation<SDWebImageDownloaderOperation> *downloadOperation;
-
-@end
-
-@implementation SDWebImageDownloadToken
-
-- (void)cancel {
-    if (self.downloadOperation) {
-        SDWebImageDownloadToken *cancelToken = self.downloadOperationCancelToken;
-        if (cancelToken) {
-            [self.downloadOperation cancel:cancelToken];
-        }
-    }
-}
+@property (nonatomic, weak, nullable) SDWebImageDownloader *downloader;
 
 @end
 
@@ -284,6 +274,7 @@
     token.downloadOperation = operation;
     token.url = url;
     token.downloadOperationCancelToken = downloadOperationCancelToken;
+    token.downloader = self;
 
     return token;
 }
@@ -398,3 +389,23 @@ didReceiveResponse:(NSURLResponse *)response
 }
 
 @end
+
+@implementation SDWebImageDownloadToken
+
+- (void)cancel {
+    @synchronized (self) {
+        if (!self.downloadOperationCancelToken) {
+            return;
+        }
+        if (self.downloader) {
+            // Downloader is alive, cancel token
+            [self.downloader cancel:self];
+        } else {
+            // Downloader is dealloced, only cancel download operation
+            [self.downloadOperation cancel:self.downloadOperationCancelToken];
+        }
+        self.downloadOperationCancelToken = nil;
+    }
+}
+
+@end

SDWebImage/SDWebImageDownloaderConfig.h

@@ -24,7 +24,8 @@ typedef NS_ENUM(NSInteger, SDWebImageDownloaderExecutionOrder) {
 @interface SDWebImageDownloaderConfig : NSObject <NSCopying>
 
 /**
- Gets/Sets the default downloader config.
+ Gets/Sets the default downloader config used for shared instance or initialization when it does not provide any downloader config. Such as `SDWebImageDownloader.sharedDownloader`.
+ @note You should not pass nil to this value.
  */
 @property (nonatomic, class, nonnull) SDWebImageDownloaderConfig *defaultDownloaderConfig;
 
@@ -35,46 +36,54 @@ typedef NS_ENUM(NSInteger, SDWebImageDownloaderExecutionOrder) {
 @property (nonatomic, assign) BOOL shouldDecompressImages;
 
 /**
- *  The maximum number of concurrent downloads
+ * The maximum number of concurrent downloads.
+ * Defaults to 6.
  */
 @property (nonatomic, assign) NSInteger maxConcurrentDownloads;
 
 /**
- *  The timeout value (in seconds) for the download operation. Default: 15.0.
+ * The timeout value (in seconds) for the download operation.
+ * Defaults to 15.0.
  */
 @property (nonatomic, assign) NSTimeInterval downloadTimeout;
 
 /**
- * The custom session configuration in use by NSURLSession.
+ * The custom session configuration in use by NSURLSession. If you don't provide one, we will use `defaultSessionConfiguration` instead.
+ * Defatuls to nil.
+ * @note The `timeoutIntervalForRequest` will be override by `downloadTimeout` config.
  */
-@property (nonatomic, strong, nonnull) NSURLSessionConfiguration *sessionConfiguration;
+@property (nonatomic, strong, nullable) NSURLSessionConfiguration *sessionConfiguration;
 
 /**
  * Gets/Sets a subclass of `SDWebImageDownloaderOperation` as the default
  * `NSOperation` to be used each time SDWebImage constructs a request
  * operation to download an image.
- *
+ * Defaults to nil.
  * @note Passing `NSOperation<SDWebImageDownloaderOperation>` to set as default. Passing `nil` will revert to `SDWebImageDownloaderOperation`.
  */
 @property (nonatomic, assign, nullable) Class operationClass;
 
 /**
- * Changes download operations execution order. Default value is `SDWebImageDownloaderFIFOExecutionOrder`.
+ * Changes download operations execution order.
+ * Defaults to `SDWebImageDownloaderFIFOExecutionOrder`.
  */
 @property (nonatomic, assign) SDWebImageDownloaderExecutionOrder executionOrder;
 
 /**
- *  Set the default URL credential to be set for request operations.
+ * Set the default URL credential to be set for request operations.
+ * Defaults to nil.
  */
 @property (nonatomic, strong, nullable) NSURLCredential *urlCredential;
 
 /**
- * Set username
+ * Set username using for HTTP Basic authentication.
+ * Defaults to nil.
  */
 @property (nonatomic, copy, nullable) NSString *username;
 
 /**
- * Set password
+ * Set password using for HTTP Basic authentication.
+ * Defautls to nil.
  */
 @property (nonatomic, copy, nullable) NSString *password;
 

SDWebImage/SDWebImageDownloaderConfig.m

@@ -29,7 +29,7 @@ static SDWebImageDownloaderConfig * _defaultDownloaderConfig;
     self = [super init];
     if (self) {
         _shouldDecompressImages = YES;
-        _maxConcurrentDownloads = 3;
+        _maxConcurrentDownloads = 6;
         _downloadTimeout = 15.0;
         _executionOrder = SDWebImageDownloaderFIFOExecutionOrder;
     }