SDWebImageManager是SDWebImage的核心類。它擁有一個SDWebImageCache和一個SDWebImageDownloader屬性，分別用於圖片的緩存和下載處理。雖然是核心類，但它的源碼很簡單，這是因為相應的功能職責進行了良好的分類。下面我們來看一下它的源碼。
1.SDWebImageOptions
typedef NS_OPTIONS(NSUInteger, SDWebImageOptions) { /** * By default, when a URL fail to be downloaded, the URL is blacklisted so the library won't keep trying. * This flag disable this blacklisting. */ //默認情況下，當一個URL下載失敗的時候，這個URL會被加入黑名單列表，下次再有這個url的請求則停止請求。如果為true，這個值表示需要再嘗試請求。 SDWebImageRetryFailed = 1 << 0, /** * By default, image downloads are started during UI interactions, this flags disable this feature, * leading to delayed download on UIScrollView deceleration for instance. */ //默認情況下，當UI可以交互的時候就開始加載圖片。這個標記可以阻止這個時候加載。而是當UIScrollView開始減速滑動的時候開始加載。 SDWebImageLowPriority = 1 << 1, /** * This flag disables on-disk caching */ //這個屬性禁止磁盤緩存 SDWebImageCacheMemoryOnly = 1 << 2, /** * This flag enables progressive download, the image is displayed progressively during download as a browser would do. * By default, the image is only displayed once completely downloaded. */ //這個標記允許圖片在加載過程中顯示，就像瀏覽器那樣。默認情況下，圖片只會在加載完成以后再顯示。 SDWebImageProgressiveDownload = 1 << 3, /** * Even if the image is cached, respect the HTTP response cache control, and refresh the image from remote location if needed. * The disk caching will be handled by NSURLCache instead of SDWebImage leading to slight performance degradation. * This option helps deal with images changing behind the same request URL, e.g. Facebook graph api profile pics. * If a cached image is refreshed, the completion block is called once with the cached image and again with the final image. * * Use this flag only if you can't make your URLs static with embedded cache busting parameter. */ /* *即使本地已經緩存了圖片，但是根據HTTP的緩存策略去網絡上加載圖片。也就是說本地緩存了也不管了，嘗試從網絡上加載數據。但是具體是從代理加載、HTTP緩存加載、還是原始服務器加載這個就根據HTTP的請求頭配置。 *使用NSURLCache而不是SDWebImage來處理磁盤緩存。從而可能會導致輕微的性能損害。 *這個選項專門用於處理，url地址沒有變，但是url對應的圖片數據在服務器改變的情況。 *如果一個緩存圖片更新了，則completion這個回調會被調用兩次，一次返回緩存圖片，一次返回最終圖片。 *我們只有在不能確保URL和它對應的內容不能完全對應的時候才使用這個標記。 */ SDWebImageRefreshCached = 1 << 4, /** * In iOS 4+, continue the download of the image if the app goes to background. This is achieved by asking the system for * extra time in background to let the request finish. If the background task expires the operation will be cancelled. */ //當應用進入后台以后，圖片繼續下載。應用進入后台以后，通過向系統申請額外的時間來完成。如果時間超時，那么下載操作會被取消。 SDWebImageContinueInBackground = 1 << 5, /** * Handles cookies stored in NSHTTPCookieStore by setting * NSMutableURLRequest.HTTPShouldHandleCookies = YES; */ //處理緩存在`NSHTTPCookieStore`對象里面的cookie。通過設置`NSMutableURLRequest.HTTPShouldHandleCookies = YES`來實現的。 SDWebImageHandleCookies = 1 << 6, /** * Enable to allow untrusted SSL certificates. * Useful for testing purposes. Use with caution in production. */ //允許非信任的SSL證書請求。 //在測試的時候很有用。但是正式環境要小心使用。 SDWebImageAllowInvalidSSLCertificates = 1 << 7, /** * By default, images are loaded in the order in which they were queued. This flag moves them to * the front of the queue. */ //默認情況下，圖片加載的順序是根據加入隊列的順序加載的。但是這個標記會把任務加入隊列的最前面。 SDWebImageHighPriority = 1 << 8, /** * By default, placeholder images are loaded while the image is loading. This flag will delay the loading * of the placeholder image until after the image has finished loading. */ //默認情況下，在圖片加載的過程中，會顯示占位圖。 //但是這個標記會阻止顯示占位圖直到圖片加載完成。 SDWebImageDelayPlaceholder = 1 << 9, /** * We usually don't call transformDownloadedImage delegate method on animated images, * as most transformation code would mangle it. * Use this flag to transform them anyway. */ //默認情況下，我們不會去調用`animated images`(估計就是多張圖片循環顯示或者GIF圖片)的`transformDownloadedImage`代理方法來處理圖片。因為大部分transformation操作會對圖片做無用處理。 //用這個標記表示無論如何都要對圖片做transform處理。 SDWebImageTransformAnimatedImage = 1 << 10, /** * By default, image is added to the imageView after download. But in some cases, we want to * have the hand before setting the image (apply a filter or add it with cross-fade animation for instance) * Use this flag if you want to manually set the image in the completion when success */ //默認情況下，圖片在下載完成以后都會被自動加載到UIImageView對象上面。但是有時我們希望UIImageView加載我們手動處理以后的圖片。 //這個標記允許我們在completion這個Block中手動設置處理好以后的圖片。 SDWebImageAvoidAutoSetImage = 1 << 11, /** * By default, images are decoded respecting their original size. On iOS, this flag will scale down the * images to a size compatible with the constrained memory of devices. * If `SDWebImageProgressiveDownload` flag is set the scale down is deactivated. */ //默認情況下，圖片會按照它的原始大小來解碼顯示。根據設備的內存限制，這個屬性會調整圖片的尺寸到合適的大小再解碼。 //如果`SDWebImageProgressiveDownload`標記被設置了，則這個flag不起作用。 SDWebImageScaleDownLargeImages = 1 << 12 };
2.宏定義
/** 圖片下載完成回調Block(外部使用，一般在我們常使用的視圖分類方法中用) @param image 圖片 @param error 錯誤信息 @param cacheType 圖片獲取方式(本地緩存;內存緩存;網絡) @param imageURL 圖片URL */ typedef void(^SDExternalCompletionBlock)(UIImage * _Nullable image, NSError * _Nullable error, SDImageCacheType cacheType, NSURL * _Nullable imageURL); /** 圖片下載完成回調Block(內部使用，僅在本類中使用) @param image 圖片，如果請求出錯，那么image參數為nil @param data 圖片數據 @param error 錯誤信息 @param cacheType 圖片獲取方式(本地緩存;內存緩存;網絡) @param finished 是否下載完成 @param imageURL 圖片URL */ typedef void(^SDInternalCompletionBlock)(UIImage * _Nullable image, NSData * _Nullable data, NSError * _Nullable error, SDImageCacheType cacheType, BOOL finished, NSURL * _Nullable imageURL); /** 對URL格式做處理，在方法cacheKeyForURL:中使用 @param url URL @return 處理之后的URL */ typedef NSString * _Nullable (^SDWebImageCacheKeyFilterBlock)(NSURL * _Nullable url);
3.協議SDWebImageManagerDelegate
@protocol SDWebImageManagerDelegate <NSObject> @optional /** 在緩存中沒有找到圖片，控制是否去下載圖片 @param imageManager SDWebImageManager @param imageURL 圖片URL @return YES/NO */ - (BOOL)imageManager:(nonnull SDWebImageManager *)imageManager shouldDownloadImageForURL:(nullable NSURL *)imageURL; /** 圖片下載完成，在保存到磁盤和內存之前，對圖片進行轉換(主要是針對動態圖) @param imageManager SDWebImageManager @param image 圖片 @param imageURL 圖片URL @return 轉換之后的圖片 */ - (nullable UIImage *)imageManager:(nonnull SDWebImageManager *)imageManager transformDownloadedImage:(nullable UIImage *)image withURL:(nullable NSURL *)imageURL; @end
4.SDWebImageCombinedOperation
SDWebImageCombinedOperation是對每一個下載任務的封裝，它最重要的是提供了一個取消任務功能。
@interface SDWebImageCombinedOperation : NSObject <SDWebImageOperation> @property (assign, nonatomic, getter = isCancelled) BOOL cancelled; //!<用於判斷Operation是否已經取消 @property (copy, nonatomic, nullable) SDWebImageNoParamsBlock cancelBlock; //!<取消回調的Block @property (strong, nonatomic, nullable) NSOperation *cacheOperation; //!<NSOperation對象。可以通過這個屬性取消一個NSOperation @end @implementation SDWebImageCombinedOperation /** 取消Operation的回調Block @param cancelBlock 回調Block */ - (void)setCancelBlock:(nullable SDWebImageNoParamsBlock)cancelBlock { // check if the operation is already cancelled, then we just call the cancelBlock if (self.isCancelled) { if (cancelBlock) { cancelBlock(); } _cancelBlock = nil; // don't forget to nil the cancelBlock, otherwise we will get crashes } else { _cancelBlock = [cancelBlock copy]; } } /** 這個方法繼承自`SDWebImageOperation`協議，方法里面會調用`SDWebImageDownlaoderOperation`或者`NSOperation`的cancel方法 */ - (void)cancel { self.cancelled = YES; if (self.cacheOperation) { //調用`SDWebImageDownlaoderOperation`或者`NSOperation`的cancel方法 [self.cacheOperation cancel]; self.cacheOperation = nil; } if (self.cancelBlock) { self.cancelBlock(); // TODO: this is a temporary fix to #809. // Until we can figure the exact cause of the crash, going with the ivar instead of the setter // self.cancelBlock = nil; _cancelBlock = nil; } } @end
5.SDWebImageManager的屬性
//.h文件 @property (weak, nonatomic, nullable) id <SDWebImageManagerDelegate> delegate; //!<代理 @property (strong, nonatomic, readonly, nullable) SDImageCache *imageCache; //!<緩存對象 @property (strong, nonatomic, readonly, nullable) SDWebImageDownloader *imageDownloader; //!<下載對象 //.m文件 @property (strong, nonatomic, readwrite, nonnull) SDImageCache *imageCache; //!<重寫為可讀寫的緩存對象 @property (strong, nonatomic, readwrite, nonnull) SDWebImageDownloader *imageDownloader; //!<重寫為可讀寫的下載對象 @property (strong, nonatomic, nonnull) NSMutableSet<NSURL *> *failedURLs; //!<加載失敗的URL @property (strong, nonatomic, nonnull) NSMutableArray<SDWebImageCombinedOperation *> *runningOperations; //!<當前正在加載的任務
6.SDWebImageManager的方法
6.1初始化
+ (nonnull instancetype)sharedManager { static dispatch_once_t once; static id instance; dispatch_once(&once, ^{ instance = [self new]; }); return instance; } - (nonnull instancetype)init { SDImageCache *cache = [SDImageCache sharedImageCache]; SDWebImageDownloader *downloader = [SDWebImageDownloader sharedDownloader]; return [self initWithCache:cache downloader:downloader]; } /** 初始化 @param cache SDImageCache對象 @param downloader SDWebImageDownloader對象 @return 返回初始化結果 */ - (nonnull instancetype)initWithCache:(nonnull SDImageCache *)cache downloader:(nonnull SDWebImageDownloader *)downloader { if ((self = [super init])) { _imageCache = cache; _imageDownloader = downloader; //用於保存加載失敗的url集合 _failedURLs = [NSMutableSet new]; //用於保存當前正在加載的Operation _runningOperations = [NSMutableArray new]; } return self; }
6.2緩存查詢
/** 根據url獲取url對應的緩存key。如果有實現指定的url轉換key的Block，則用這個方式轉換為key；否則直接用url的絕對路徑作為key @param url url @return 緩存的key */ - (nullable NSString *)cacheKeyForURL:(nullable NSURL *)url { if (!url) { return @""; } if (self.cacheKeyFilter) { return self.cacheKeyFilter(url); } else { return url.absoluteString; } } /** url的緩存是否存在 @param url 緩存數據對應的url @param completionBlock 緩存結果回調 */ - (void)cachedImageExistsForURL:(nullable NSURL *)url completion:(nullable SDWebImageCheckCacheCompletionBlock)completionBlock { NSString *key = [self cacheKeyForURL:url]; //內存里面是否有key的緩存 BOOL isInMemoryCache = ([self.imageCache imageFromMemoryCacheForKey:key] != nil); //內存緩存 if (isInMemoryCache) { // making sure we call the completion block on the main queue dispatch_async(dispatch_get_main_queue(), ^{ if (completionBlock) { completionBlock(YES); } }); return; } //磁盤緩存 [self.imageCache diskImageExistsWithKey:key completion:^(BOOL isInDiskCache) { // the completion block of checkDiskCacheForImageWithKey:completion: is always called on the main queue, no need to further dispatch if (completionBlock) { completionBlock(isInDiskCache); } }]; } /** url是否有磁盤緩存數據 @param url url @param completionBlock 緩存結果回調 */ - (void)diskImageExistsForURL:(nullable NSURL *)url completion:(nullable SDWebImageCheckCacheCompletionBlock)completionBlock { NSString *key = [self cacheKeyForURL:url]; [self.imageCache diskImageExistsWithKey:key completion:^(BOOL isInDiskCache) { // the completion block of checkDiskCacheForImageWithKey:completion: is always called on the main queue, no need to further dispatch if (completionBlock) { completionBlock(isInDiskCache); } }]; }
6.3下載(SDWebImage的核心方法)
/** 核心方法。UIView、UIImageView等分類都默認通過調用這個方法來獲取數據 @param url 圖片的url地址 @param options 獲取圖片加載處理的屬性 @param progressBlock 加載進度回調 @param completedBlock 加載完成回調 @return 返回一個加載的載體對象，以便提供給后面取消刪除等 */ - (id <SDWebImageOperation>)loadImageWithURL:(nullable NSURL *)url options:(SDWebImageOptions)options progress:(nullable SDWebImageDownloaderProgressBlock)progressBlock completed:(nullable SDInternalCompletionBlock)completedBlock { // Invoking this method without a completedBlock is pointless //如果想預先下載圖片，使用[SDWebImagePrefetcher prefetchURLs]取代本方法。預下載圖片是有很多種使用場景的，當我們使用SDWebImagePrefetcher下載圖片后，之后使用該圖片時就不用從網絡上下載了。 NSAssert(completedBlock != nil, @"If you mean to prefetch the image, use -[SDWebImagePrefetcher prefetchURLs] instead"); // Very common mistake is to send the URL using NSString object instead of NSURL. For some strange reason, Xcode won't // throw any warning for this type mismatch. Here we failsafe this error by allowing URLs to be passed as NSString. //如果傳入的url是NSString格式的，則轉換為NSURL類型再處理 if ([url isKindOfClass:NSString.class]) { url = [NSURL URLWithString:(NSString *)url]; } // Prevents app crashing on argument type error like sending NSNull instead of NSURL //如果url不是NSURL類型的對象，則置為nil if (![url isKindOfClass:NSURL.class]) { url = nil; } //圖片加載獲取獲取過程中綁定一個`SDWebImageCombinedOperation`對象，以方便后續再通過這個對象對url的加載控制。 __block SDWebImageCombinedOperation *operation = [SDWebImageCombinedOperation new]; __weak SDWebImageCombinedOperation *weakOperation = operation; BOOL isFailedUrl = NO; //當前url是否在失敗url的集合里面。在圖片的下載中，會有一些下載失敗的情況，這時候會把這些下載失敗的url放到一個集合中去，也就是加入了黑名單，默認是不會再繼續下載黑名單中的url了，但是也有例外，當options被設置為SDWebImageRetryFailed的時候，會嘗試進行重新下載。 if (url) { @synchronized (self.failedURLs) { isFailedUrl = [self.failedURLs containsObject:url]; } } //如果url長度為0 或者是 失敗的url且圖片加載處理屬性不包含SDWebImageRetryFailed，則直接返回 if (url.absoluteString.length == 0 || (!(options & SDWebImageRetryFailed) && isFailedUrl)) { //構建回調Block [self callCompletionBlockForOperation:operation completion:completedBlock error:[NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorFileDoesNotExist userInfo:nil] url:url]; return operation; } //把加載圖片的operation存入runningOperations，里面是所有正在做圖片加載過程的operation的集合 @synchronized (self.runningOperations) { [self.runningOperations addObject:operation]; } //根據url獲取url對應的key NSString *key = [self cacheKeyForURL:url]; //key為空或者圖片從內存中加載，則返回的cacheOperation是nil；其他情況cacheOperation為NSOperation對象 operation.cacheOperation = [self.imageCache queryCacheOperationForKey:key done:^(UIImage *cachedImage, NSData *cachedData, SDImageCacheType cacheType) { //如果已經取消了操作，則直接返回並且移除對應的opetation對象 if (operation.isCancelled) { [self safelyRemoveOperationFromRunning:operation]; return; } //(如果未能在緩存中找到圖片||強制刷新緩存) && (代理中未實現圖片是否下載的方法||代理中圖片是否應該下載方法返回值為YES if ((!cachedImage || options & SDWebImageRefreshCached) && (![self.delegate respondsToSelector:@selector(imageManager:shouldDownloadImageForURL:)] || [self.delegate imageManager:self shouldDownloadImageForURL:url])) { //如果從緩存中獲取了圖片並且設置了SDWebImageRefreshCached來忽略緩存，則先把緩存的圖片返回 if (cachedImage && options & SDWebImageRefreshCached) { // If image was found in the cache but SDWebImageRefreshCached is provided, notify about the cached image // AND try to re-download it in order to let a chance to NSURLCache to refresh it from server. [self callCompletionBlockForOperation:weakOperation completion:completedBlock image:cachedImage data:cachedData error:nil cacheType:cacheType finished:YES url:url]; } // download if no image or requested to refresh anyway, and download allowed by delegate //把圖片加載的`SDWebImageOptions`類型枚舉轉換為圖片下載的`SDWebImageDownloaderOptions`類型的枚舉 SDWebImageDownloaderOptions downloaderOptions = 0; if (options & SDWebImageLowPriority) downloaderOptions |= SDWebImageDownloaderLowPriority; if (options & SDWebImageProgressiveDownload) downloaderOptions |= SDWebImageDownloaderProgressiveDownload; if (options & SDWebImageRefreshCached) downloaderOptions |= SDWebImageDownloaderUseNSURLCache; if (options & SDWebImageContinueInBackground) downloaderOptions |= SDWebImageDownloaderContinueInBackground; if (options & SDWebImageHandleCookies) downloaderOptions |= SDWebImageDownloaderHandleCookies; if (options & SDWebImageAllowInvalidSSLCertificates) downloaderOptions |= SDWebImageDownloaderAllowInvalidSSLCertificates; if (options & SDWebImageHighPriority) downloaderOptions |= SDWebImageDownloaderHighPriority; if (options & SDWebImageScaleDownLargeImages) downloaderOptions |= SDWebImageDownloaderScaleDownLargeImages; //如果設置了強制刷新緩存的選項。則`SDWebImageDownloaderProgressiveDownload`選項失效並且添加`SDWebImageDownloaderIgnoreCachedResponse`選項 if (cachedImage && options & SDWebImageRefreshCached) { // force progressive off if image already cached but forced refreshing downloaderOptions &= ~SDWebImageDownloaderProgressiveDownload; // ignore image read from NSURLCache if image if cached but force refreshing downloaderOptions |= SDWebImageDownloaderIgnoreCachedResponse; } //新建一個網絡下載的操作 SDWebImageDownloadToken *subOperationToken = [self.imageDownloader downloadImageWithURL:url options:downloaderOptions progress:progressBlock completed:^(UIImage *downloadedImage, NSData *downloadedData, NSError *error, BOOL finished) { __strong __typeof(weakOperation) strongOperation = weakOperation; //如果圖片下載結束以后，對應的圖片加載操作已經取消。則什么處理都不做 if (!strongOperation || strongOperation.isCancelled) { // Do nothing if the operation was cancelled // See #699 for more details // if we would call the completedBlock, there could be a race condition between this block and another completedBlock for the same object, so if this one is called second, we will overwrite the new data } else if (error) { //如果加載出錯，則直接返回回調，並且添加到failedURLs中 [self callCompletionBlockForOperation:strongOperation completion:completedBlock error:error url:url]; if ( error.code != NSURLErrorNotConnectedToInternet && error.code != NSURLErrorCancelled && error.code != NSURLErrorTimedOut && error.code != NSURLErrorInternationalRoamingOff && error.code != NSURLErrorDataNotAllowed && error.code != NSURLErrorCannotFindHost && error.code != NSURLErrorCannotConnectToHost && error.code != NSURLErrorNetworkConnectionLost) { @synchronized (self.failedURLs) { [self.failedURLs addObject:url]; } } } else { //網絡圖片下載成功 //如果有重試失敗下載的選項，則把url從failedURLS中移除 if ((options & SDWebImageRetryFailed)) { @synchronized (self.failedURLs) { [self.failedURLs removeObject:url]; } } //是否需要保存到磁盤 BOOL cacheOnDisk = !(options & SDWebImageCacheMemoryOnly); //如果設置了強制刷新緩存 && 緩存圖片存在 && 下載圖片不存在，那么直接返回，不執行回調Block if (options & SDWebImageRefreshCached && cachedImage && !downloadedImage) { // Image refresh hit the NSURLCache cache, do not call the completion block } //如果成功下載圖片 && 圖片是動態圖片 && 實現了imageManager:transformDownloadedImage:withURL:代理方法，則進行圖片的處理 else if (downloadedImage && (!downloadedImage.images || (options & SDWebImageTransformAnimatedImage)) && [self.delegate respondsToSelector:@selector(imageManager:transformDownloadedImage:withURL:)]) { dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{ //獲取transform以后的圖片 UIImage *transformedImage = [self.delegate imageManager:self transformDownloadedImage:downloadedImage withURL:url]; //存儲transform以后的的圖片 if (transformedImage && finished) { BOOL imageWasTransformed = ![transformedImage isEqual:downloadedImage]; // pass nil if the image was transformed, so we can recalculate the data from the image [self.imageCache storeImage:transformedImage imageData:(imageWasTransformed ? nil : downloadedData) forKey:key toDisk:cacheOnDisk completion:nil]; } //回調拼接 [self callCompletionBlockForOperation:strongOperation completion:completedBlock image:transformedImage data:downloadedData error:nil cacheType:SDImageCacheTypeNone finished:finished url:url]; }); } else { //如果成功下載圖片，直接緩存和回調 if (downloadedImage && finished) { [self.imageCache storeImage:downloadedImage imageData:downloadedData forKey:key toDisk:cacheOnDisk completion:nil]; } //回調拼接 [self callCompletionBlockForOperation:strongOperation completion:completedBlock image:downloadedImage data:downloadedData error:nil cacheType:SDImageCacheTypeNone finished:finished url:url]; } } //從正在加載的圖片操作集合中移除當前操作 if (finished) { [self safelyRemoveOperationFromRunning:strongOperation]; } }]; //重置cancelBlock，取消下載operation operation.cancelBlock = ^{ [self.imageDownloader cancel:subOperationToken]; __strong __typeof(weakOperation) strongOperation = weakOperation; [self safelyRemoveOperationFromRunning:strongOperation]; }; } else if (cachedImage) { //如果獲取到了緩存圖片，則直接通過緩存圖片處理 __strong __typeof(weakOperation) strongOperation = weakOperation; [self callCompletionBlockForOperation:strongOperation completion:completedBlock image:cachedImage data:cachedData error:nil cacheType:cacheType finished:YES url:url]; [self safelyRemoveOperationFromRunning:operation]; } else { //圖片沒有緩存並且圖片也沒有下載 // Image not in cache and download disallowed by delegate __strong __typeof(weakOperation) strongOperation = weakOperation; [self callCompletionBlockForOperation:strongOperation completion:completedBlock image:nil data:nil error:nil cacheType:SDImageCacheTypeNone finished:YES url:url]; [self safelyRemoveOperationFromRunning:operation]; } }]; return operation; }
6.4其他方法
/** 保存圖片到緩存 @param image 圖片 @param url URL */ - (void)saveImageToCache:(nullable UIImage *)image forURL:(nullable NSURL *)url { if (image && url) { NSString *key = [self cacheKeyForURL:url]; [self.imageCache storeImage:image forKey:key toDisk:YES completion:nil]; } } /** 取消所有的下載 */ - (void)cancelAll { @synchronized (self.runningOperations) { NSArray<SDWebImageCombinedOperation *> *copiedOperations = [self.runningOperations copy]; [copiedOperations makeObjectsPerformSelector:@selector(cancel)]; [self.runningOperations removeObjectsInArray:copiedOperations]; } } /** 查看是否正在執行任務 @return YES/NO */ - (BOOL)isRunning { BOOL isRunning = NO; @synchronized (self.runningOperations) { isRunning = (self.runningOperations.count > 0); } return isRunning; } /** 安全移除任務 @param operation 任務 */ - (void)safelyRemoveOperationFromRunning:(nullable SDWebImageCombinedOperation*)operation { @synchronized (self.runningOperations) { if (operation) { [self.runningOperations removeObject:operation]; } } } /** 拼接回調Block並進行回調 @param operation 任務 @param completionBlock 回調Block @param error error @param url URL */ - (void)callCompletionBlockForOperation:(nullable SDWebImageCombinedOperation*)operation completion:(nullable SDInternalCompletionBlock)completionBlock error:(nullable NSError *)error url:(nullable NSURL *)url { [self callCompletionBlockForOperation:operation completion:completionBlock image:nil data:nil error:error cacheType:SDImageCacheTypeNone finished:YES url:url]; } /** 拼接回調Block並進行回調 @param operation 任務 @param completionBlock 回調Block @param image 圖片 @param data 圖片數據 @param error error @param cacheType 緩存類型 @param finished 是否完成 @param url URL */ - (void)callCompletionBlockForOperation:(nullable SDWebImageCombinedOperation*)operation completion:(nullable SDInternalCompletionBlock)completionBlock image:(nullable UIImage *)image data:(nullable NSData *)data error:(nullable NSError *)error cacheType:(SDImageCacheType)cacheType finished:(BOOL)finished url:(nullable NSURL *)url { dispatch_main_async_safe(^{ if (operation && !operation.isCancelled && completionBlock) { completionBlock(image, data, error, cacheType, finished, url); } }); }