SDImageCache和SDWebImageDownloader是SDWebImage库的最重要的两个部件,它们一起为SDWebImageManager提供服务,来完成图片的加载。SDImageCache提供了对图片的内存缓存、异步磁盘缓存、图片缓存查询等功能,下载过的图片会被缓存到内存,也可选择保存到本地磁盘,当再次请求相同图片时直接从缓存中读取图片,从而大大提高了加载速度。在SDImageCache中,内存缓存是通过 NSCache的子类
AutoPurgeCache来实现的;磁盘缓存是通过 NSFileManager
来实现文件的存储(默认路径为/Library/Caches/default/com.hackemist.SDWebImageCache.default),是异步实现的。
下面我们还是一步步来分析它的源码结构。
1.SDImageCacheType枚举类型
/** 缓存类型 */ typedef NS_ENUM(NSInteger, SDImageCacheType) { /** * The image wasn‘t available the SDWebImage caches, but was downloaded from the web. */ SDImageCacheTypeNone, //不使用 SDWebImage 缓存,从网络下载 /** * The image was obtained from the disk cache. */ SDImageCacheTypeDisk, //使用磁盘缓存 /** * The image was obtained from the memory cache. */ SDImageCacheTypeMemory //使用内存缓存 };
2.Block定义
/** 查询回调Block @param image 图片 @param data 图片数据 @param cacheType 缓存类型 */ typedef void(^SDCacheQueryCompletedBlock)(UIImage * _Nullable image, NSData * _Nullable data, SDImageCacheType cacheType); /** 磁盘缓存检查回调 @param isInCache 是否在缓存中 */ typedef void(^SDWebImageCheckCacheCompletionBlock)(BOOL isInCache); /** 磁盘缓存空间大小计算回调Block @param fileCount 文件数量 @param totalSize 总大小 */ typedef void(^SDWebImageCalculateSizeBlock)(NSUInteger fileCount, NSUInteger totalSize);
3.SDImageCache的属性
//SDImageCacheConfig.h @property (assign, nonatomic) BOOL shouldDecompressImages; //!<是否在缓存之前解压图片,此项操作可以提升性能,但是会消耗较多的内存,默认是YES。注意:如果内存不足,可以置为NO @property (assign, nonatomic) BOOL shouldDisableiCloud; //!<是否禁止iCloud备份,默认是YES @property (assign, nonatomic) BOOL shouldCacheImagesInMemory; //!<是否启用内存缓存 默认是YES @property (assign, nonatomic) NSInteger maxCacheAge; //!<磁盘缓存保留的最长时间,默认为1周 @property (assign, nonatomic) NSUInteger maxCacheSize; //!<磁盘缓存最大容量,以字节为单位,默认为0,表示不做限制 //SDImageCache.h @property (nonatomic, nonnull, readonly) SDImageCacheConfig *config; //!<SDImageCacheConfig @property (assign, nonatomic) NSUInteger maxMemoryCost; //!<内存最大容量 @property (assign, nonatomic) NSUInteger maxMemoryCountLimit; //!<缓存中可以存放缓存的最大数量,与NSCache相关 //SDImageCache.m @property (strong, nonatomic, nonnull) NSCache *memCache; //!<内存缓存 @property (strong, nonatomic, nonnull) NSString *diskCachePath; //!<磁盘缓存路径 @property (strong, nonatomic, nullable) NSMutableArray<NSString *> *customPaths; //!<自定义的缓存路径 @property (SDDispatchQueueSetterSementics, nonatomic, nullable) dispatch_queue_t ioQueue; //!<磁盘缓存操作的串行队列
4.SDImageCache的方法
从源码表面来看,SDImageCache提供的方法很多,但其方法主要围绕着图片缓存的添加、删除、查询等,只不过每个功能可能有多种实现方式,但本质上是一样的。
4.1初始化
/** 单例方法,返回一个全局的缓存实例 @return 缓存实例 */ + (nonnull instancetype)sharedImageCache { static dispatch_once_t once; static id instance; dispatch_once(&once, ^{ instance = [self new]; }); return instance; } - (instancetype)init { return [self initWithNamespace:@"default"]; } /** 使用指定的命名空间实例化一个新的缓存存储 @param ns 命名空间 @return 缓存实例 */ - (nonnull instancetype)initWithNamespace:(nonnull NSString *)ns { NSString *path = [self makeDiskCachePath:ns]; return [self initWithNamespace:ns diskCacheDirectory:path]; } /** 使用指定的命名空间实例化一个新的缓存存储和目录 @param ns 命名空间 @param directory 缓存所在目录 @return 缓存实例 */ - (nonnull instancetype)initWithNamespace:(nonnull NSString *)ns diskCacheDirectory:(nonnull NSString *)directory { if ((self = [super init])) { NSString *fullNamespace = [@"com.hackemist.SDWebImageCache." stringByAppendingString:ns]; // Create IO serial queue _ioQueue = dispatch_queue_create("com.hackemist.SDWebImageCache", DISPATCH_QUEUE_SERIAL); //初始化缓存策略配置对象 _config = [[SDImageCacheConfig alloc] init]; // Init the memory cache // 初始化内存缓存对象 _memCache = [[AutoPurgeCache alloc] init]; _memCache.name = fullNamespace; // 初始化磁盘缓存路径 if (directory != nil) { _diskCachePath = [directory stringByAppendingPathComponent:fullNamespace]; } else { NSString *path = [self makeDiskCachePath:ns]; _diskCachePath = path; } dispatch_sync(_ioQueue, ^{ _fileManager = [NSFileManager new]; }); #if SD_UIKIT // Subscribe to app events //当应用收到内存警告的时候,清除内存缓存 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(clearMemory) name:UIApplicationDidReceiveMemoryWarningNotification object:nil]; //当应用终止的时候,清除老数据 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deleteOldFiles) name:UIApplicationWillTerminateNotification object:nil]; //当应用进入后台的时候,在后台删除老数据 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(backgroundDeleteOldFiles) name:UIApplicationDidEnterBackgroundNotification object:nil]; #endif } return self; }
上面就是SDImageCache的初始化过程,主要是初始化内存缓存对象和初始化磁盘缓存目录,以及对一些默认参数的赋值。
4.2缓存图片
/** 以key为键值将图片image存储到缓存中 @param image 图片 @param key key @param completionBlock 回调Block */ - (void)storeImage:(nullable UIImage *)image forKey:(nullable NSString *)key completion:(nullable SDWebImageNoParamsBlock)completionBlock { [self storeImage:image imageData:nil forKey:key toDisk:YES completion:completionBlock]; } /** 以key为键值将图片image存储到缓存中 @param image 图片 @param key key @param toDisk 是否写入磁盘缓存 @param completionBlock 回调Block */ - (void)storeImage:(nullable UIImage *)image forKey:(nullable NSString *)key toDisk:(BOOL)toDisk completion:(nullable SDWebImageNoParamsBlock)completionBlock { [self storeImage:image imageData:nil forKey:key toDisk:toDisk completion:completionBlock]; } /** 把一张图片存入缓存的具体实现 @param image 缓存的图片对象 @param imageData 缓存的图片数据 @param key 缓存对应的key @param toDisk 是否缓存到磁盘 @param completionBlock 缓存完成回调 */ - (void)storeImage:(nullable UIImage *)image imageData:(nullable NSData *)imageData forKey:(nullable NSString *)key toDisk:(BOOL)toDisk completion:(nullable SDWebImageNoParamsBlock)completionBlock { if (!image || !key) { if (completionBlock) { completionBlock(); } return; } // if memory cache is enabled //缓存到内存 if (self.config.shouldCacheImagesInMemory) { //计算缓存数据的大小 NSUInteger cost = SDCacheCostForImage(image); //加入缓存 [self.memCache setObject:image forKey:key cost:cost]; } if (toDisk) { //在一个串行队列中做磁盘缓存操作 dispatch_async(self.ioQueue, ^{ @autoreleasepool { NSData *data = imageData; if (!data && image) { //获取图片的类型GIF/PNG等 SDImageFormat imageFormatFromData = [NSData sd_imageFormatForImageData:data]; //根据指定的SDImageFormat,把图片转换为对应的data数据 data = [image sd_imageDataAsFormat:imageFormatFromData]; } //把处理好了的数据存入磁盘 [self storeImageDataToDisk:data forKey:key]; } if (completionBlock) { dispatch_async(dispatch_get_main_queue(), ^{ completionBlock(); }); } }); } else { if (completionBlock) { completionBlock(); } } } /** 把图片资源存入磁盘 @param imageData 图片数据 @param key key */ - (void)storeImageDataToDisk:(nullable NSData *)imageData forKey:(nullable NSString *)key { if (!imageData || !key) { return; } [self checkIfQueueIsIOQueue]; //缓存目录是否已经初始化 if (![_fileManager fileExistsAtPath:_diskCachePath]) { [_fileManager createDirectoryAtPath:_diskCachePath withIntermediateDirectories:YES attributes:nil error:NULL]; } // get cache Path for image key //获取key对应的完整缓存路径 NSString *cachePathForKey = [self defaultCachePathForKey:key]; // transform to NSUrl NSURL *fileURL = [NSURL fileURLWithPath:cachePathForKey]; //把数据存入路径 [_fileManager createFileAtPath:cachePathForKey contents:imageData attributes:nil]; // disable iCloud backup if (self.config.shouldDisableiCloud) { [fileURL setResourceValue:@YES forKey:NSURLIsExcludedFromBackupKey error:nil]; } }
4.3查询图片
/** 根据key判断磁盘缓存中是否存在图片 @param key key @param completionBlock 回调Block */ - (void)diskImageExistsWithKey:(nullable NSString *)key completion:(nullable SDWebImageCheckCacheCompletionBlock)completionBlock { dispatch_async(_ioQueue, ^{ BOOL exists = [_fileManager fileExistsAtPath:[self defaultCachePathForKey:key]]; // fallback because of https://github.com/rs/SDWebImage/pull/976 that added the extension to the disk file name // checking the key with and without the extension if (!exists) { exists = [_fileManager fileExistsAtPath:[self defaultCachePathForKey:key].stringByDeletingPathExtension]; } if (completionBlock) { dispatch_async(dispatch_get_main_queue(), ^{ completionBlock(exists); }); } }); } /** 根据key获取缓存在内存中的图片 @param key key @return 缓存的图片 */ - (nullable UIImage *)imageFromMemoryCacheForKey:(nullable NSString *)key { return [self.memCache objectForKey:key]; } /** 根据key获取缓存在磁盘中的图片 @param key key @return 缓存的图片 */ - (nullable UIImage *)imageFromDiskCacheForKey:(nullable NSString *)key { UIImage *diskImage = [self diskImageForKey:key]; if (diskImage && self.config.shouldCacheImagesInMemory) { NSUInteger cost = SDCacheCostForImage(diskImage); [self.memCache setObject:diskImage forKey:key cost:cost]; } return diskImage; } /** 根据key获取缓存图片(先从内存中搜索,再去磁盘中搜索) @param key key @return 缓存的图片 */ - (nullable UIImage *)imageFromCacheForKey:(nullable NSString *)key { // First check the in-memory cache... UIImage *image = [self imageFromMemoryCacheForKey:key]; if (image) { return image; } // Second check the disk cache... image = [self imageFromDiskCacheForKey:key]; return image; } /** 根据指定的key,获取存储在磁盘上的数据 @param key 图片对应的key @return 返回图片数据 */ - (nullable NSData *)diskImageDataBySearchingAllPathsForKey:(nullable NSString *)key { //获取key对应的path NSString *defaultPath = [self defaultCachePathForKey:key]; NSData *data = [NSData dataWithContentsOfFile:defaultPath]; if (data) { return data; } // fallback because of https://github.com/rs/SDWebImage/pull/976 that added the extension to the disk file name // checking the key with and without the extension //如果key没有后缀名,则会走到这里通过这里读取 data = [NSData dataWithContentsOfFile:defaultPath.stringByDeletingPathExtension]; if (data) { return data; } //如果在默认路径没有找到图片,则在自定义路径迭代查找 NSArray<NSString *> *customPaths = [self.customPaths copy]; for (NSString *path in customPaths) { NSString *filePath = [self cachePathForKey:key inPath:path]; NSData *imageData = [NSData dataWithContentsOfFile:filePath]; if (imageData) { return imageData; } // fallback because of https://github.com/rs/SDWebImage/pull/976 that added the extension to the disk file name // checking the key with and without the extension imageData = [NSData dataWithContentsOfFile:filePath.stringByDeletingPathExtension]; if (imageData) { return imageData; } } return nil; } /** 根据指定的key获取image对象 @param key key @return image对象 */ - (nullable UIImage *)diskImageForKey:(nullable NSString *)key { //获取磁盘数据 NSData *data = [self diskImageDataBySearchingAllPathsForKey:key]; if (data) { UIImage *image = [UIImage sd_imageWithData:data]; image = [self scaledImageForKey:key image:image]; if (self.config.shouldDecompressImages) { image = [UIImage decodedImageWithImage:image]; } return image; } else { return nil; } } - (nullable UIImage *)scaledImageForKey:(nullable NSString *)key image:(nullable UIImage *)image { return SDScaledImageForKey(key, image); } /** 在缓存中查询对应key的数据 @param key 要查询的key @param doneBlock 查询结束以后的回调Block @return 返回做查询操作的NSOperation */ - (nullable NSOperation *)queryCacheOperationForKey:(nullable NSString *)key done:(nullable SDCacheQueryCompletedBlock)doneBlock { if (!key) { if (doneBlock) { doneBlock(nil, nil, SDImageCacheTypeNone); } return nil; } // First check the in-memory cache... //首先从内存中查找图片 UIImage *image = [self imageFromMemoryCacheForKey:key]; if (image) { NSData *diskData = nil; if ([image isGIF]) { diskData = [self diskImageDataBySearchingAllPathsForKey:key]; } if (doneBlock) { doneBlock(image, diskData, SDImageCacheTypeMemory); } return nil; } //新建一个NSOperation来获取磁盘图片 NSOperation *operation = [NSOperation new]; dispatch_async(self.ioQueue, ^{ if (operation.isCancelled) { // do not call the completion if cancelled return; } //在一个自动释放池中处理图片从磁盘加载 @autoreleasepool { NSData *diskData = [self diskImageDataBySearchingAllPathsForKey:key]; UIImage *diskImage = [self diskImageForKey:key]; if (diskImage && self.config.shouldCacheImagesInMemory) { NSUInteger cost = SDCacheCostForImage(diskImage); //把从磁盘取出的缓存图片加入内存缓存中 [self.memCache setObject:diskImage forKey:key cost:cost]; } //图片处理完成以后回调Block if (doneBlock) { dispatch_async(dispatch_get_main_queue(), ^{ doneBlock(diskImage, diskData, SDImageCacheTypeDisk); }); } } }); return operation; }
4.4删除图片
#pragma mark - Remove Ops /** 通过key从磁盘和内存中移除缓存 @param key key @param completion 回调Block */ - (void)removeImageForKey:(nullable NSString *)key withCompletion:(nullable SDWebImageNoParamsBlock)completion { [self removeImageForKey:key fromDisk:YES withCompletion:completion]; } /** 移除指定key对应的缓存数据 @param key key @param fromDisk 是否也清除磁盘缓存 @param completion 回调 */ - (void)removeImageForKey:(nullable NSString *)key fromDisk:(BOOL)fromDisk withCompletion:(nullable SDWebImageNoParamsBlock)completion { if (key == nil) { return; } //移除内存缓存 if (self.config.shouldCacheImagesInMemory) { [self.memCache removeObjectForKey:key]; } //移除磁盘缓存 if (fromDisk) { dispatch_async(self.ioQueue, ^{ [_fileManager removeItemAtPath:[self defaultCachePathForKey:key] error:nil]; if (completion) { dispatch_async(dispatch_get_main_queue(), ^{ completion(); }); } }); } else if (completion){ completion(); } } #pragma mark - Cache clean Ops 内存缓存清理相关操作 /** 清理当前SDImageCache对象的内存缓存 */ - (void)clearMemory { [self.memCache removeAllObjects]; } /** 移除所有的磁盘缓存图片数据 @param completion 移除完成以后回调 */ - (void)clearDiskOnCompletion:(nullable SDWebImageNoParamsBlock)completion { dispatch_async(self.ioQueue, ^{ [_fileManager removeItemAtPath:self.diskCachePath error:nil]; [_fileManager createDirectoryAtPath:self.diskCachePath withIntermediateDirectories:YES attributes:nil error:NULL]; if (completion) { dispatch_async(dispatch_get_main_queue(), ^{ completion(); }); } }); } - (void)deleteOldFiles { [self deleteOldFilesWithCompletionBlock:nil]; } /** 当应用终止或者进入后台都会调用这个方法来清除缓存图片 这里会根据图片存储时间来清理图片,默认是一周,从最老的图片开始清理。如果图片缓存空间小于一个规定值,则不考虑 @param completionBlock 清除完成以后的回调 */ - (void)deleteOldFilesWithCompletionBlock:(nullable SDWebImageNoParamsBlock)completionBlock { dispatch_async(self.ioQueue, ^{ //获取磁盘缓存的默认根目录 NSURL *diskCacheURL = [NSURL fileURLWithPath:self.diskCachePath isDirectory:YES]; NSArray<NSString *> *resourceKeys = @[NSURLIsDirectoryKey, NSURLContentModificationDateKey, NSURLTotalFileAllocatedSizeKey]; // This enumerator prefetches useful properties for our cache files. NSDirectoryEnumerator *fileEnumerator = [_fileManager enumeratorAtURL:diskCacheURL includingPropertiesForKeys:resourceKeys options:NSDirectoryEnumerationSkipsHiddenFiles errorHandler:NULL]; NSDate *expirationDate = [NSDate dateWithTimeIntervalSinceNow:-self.config.maxCacheAge]; NSMutableDictionary<NSURL *, NSDictionary<NSString *, id> *> *cacheFiles = [NSMutableDictionary dictionary]; NSUInteger currentCacheSize = 0; // Enumerate all of the files in the cache directory. This loop has two purposes: // // 1. Removing files that are older than the expiration date. // 2. Storing file attributes for the size-based cleanup pass. //迭代缓存目录。有两个目的: //1 删除比指定日期更老的图片 //2 记录文件的大小,以提供给后面删除使用 NSMutableArray<NSURL *> *urlsToDelete = [[NSMutableArray alloc] init]; for (NSURL *fileURL in fileEnumerator) { NSError *error; //获取指定url对应文件的指定三种属性的key和value NSDictionary<NSString *, id> *resourceValues = [fileURL resourceValuesForKeys:resourceKeys error:&error]; // Skip directories and errors. //如果是文件夹则返回 if (error || !resourceValues || [resourceValues[NSURLIsDirectoryKey] boolValue]) { continue; } // Remove files that are older than the expiration date; //获取指定url文件对应的修改日期 NSDate *modificationDate = resourceValues[NSURLContentModificationDateKey]; //如果修改日期大于指定日期,则加入要移除的数组里 if ([[modificationDate laterDate:expirationDate] isEqualToDate:expirationDate]) { [urlsToDelete addObject:fileURL]; continue; } // Store a reference to this file and account for its total size. //获取指定的url对应的文件的大小,并且把url与对应大小存入一个字典中 NSNumber *totalAllocatedSize = resourceValues[NSURLTotalFileAllocatedSizeKey]; currentCacheSize += totalAllocatedSize.unsignedIntegerValue; cacheFiles[fileURL] = resourceValues; } //删除所有最后修改日期大于指定日期的所有文件 for (NSURL *fileURL in urlsToDelete) { [_fileManager removeItemAtURL:fileURL error:nil]; } // If our remaining disk cache exceeds a configured maximum size, perform a second // size-based cleanup pass. We delete the oldest files first. //如果当前缓存的大小超过了默认大小,则按照日期删除,直到缓存大小<默认大小的一半 if (self.config.maxCacheSize > 0 && currentCacheSize > self.config.maxCacheSize) { // Target half of our maximum cache size for this cleanup pass. const NSUInteger desiredCacheSize = self.config.maxCacheSize / 2; // Sort the remaining cache files by their last modification time (oldest first). //根据文件创建的时间排序 NSArray<NSURL *> *sortedFiles = [cacheFiles keysSortedByValueWithOptions:NSSortConcurrent usingComparator:^NSComparisonResult(id obj1, id obj2) { return [obj1[NSURLContentModificationDateKey] compare:obj2[NSURLContentModificationDateKey]]; }]; // Delete files until we fall below our desired cache size. //迭代删除缓存,直到缓存大小是默认缓存大小的一半 for (NSURL *fileURL in sortedFiles) { if ([_fileManager removeItemAtURL:fileURL error:nil]) { NSDictionary<NSString *, id> *resourceValues = cacheFiles[fileURL]; NSNumber *totalAllocatedSize = resourceValues[NSURLTotalFileAllocatedSizeKey]; currentCacheSize -= totalAllocatedSize.unsignedIntegerValue; if (currentCacheSize < desiredCacheSize) { break; } } } } //执行完毕,主线程回调 if (completionBlock) { dispatch_async(dispatch_get_main_queue(), ^{ completionBlock(); }); } }); } #if SD_UIKIT /** 应用进入后台的时候,调用这个方法 */ - (void)backgroundDeleteOldFiles { Class UIApplicationClass = NSClassFromString(@"UIApplication"); if(!UIApplicationClass || ![UIApplicationClass respondsToSelector:@selector(sharedApplication)]) { return; } UIApplication *application = [UIApplication performSelector:@selector(sharedApplication)]; //如果backgroundTask对应的时间结束了,任务还没有处理完成,则直接终止任务 __block UIBackgroundTaskIdentifier bgTask = [application beginBackgroundTaskWithExpirationHandler:^{ // Clean up any unfinished task business by marking where you // stopped or ending the task outright. //当任务非正常终止的时候,做清理工作 [application endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; }]; // Start the long-running task and return immediately. //图片清理结束以后,处理完成 [self deleteOldFilesWithCompletionBlock:^{ //清理完成以后,终止任务 [application endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; }]; } #endif
4.5其他方法
#pragma mark - Cache paths /** 添加只读的缓存路径 @param path 路径 */ - (void)addReadOnlyCachePath:(nonnull NSString *)path { if (!self.customPaths) { self.customPaths = [NSMutableArray new]; } if (![self.customPaths containsObject:path]) { [self.customPaths addObject:path]; } } /** 获取指定key对应的完整缓存路径 @param key 对应一张图片,比如图片的名字 @param path 指定根目录 @return 完整路径 */ - (nullable NSString *)cachePathForKey:(nullable NSString *)key inPath:(nonnull NSString *)path { NSString *filename = [self cachedFileNameForKey:key]; return [path stringByAppendingPathComponent:filename]; } - (nullable NSString *)defaultCachePathForKey:(nullable NSString *)key { return [self cachePathForKey:key inPath:self.diskCachePath]; } /** MD5加密 @param key key @return 加密后的数据 */ - (nullable NSString *)cachedFileNameForKey:(nullable NSString *)key { const char *str = key.UTF8String; if (str == NULL) { str = ""; } unsigned char r[CC_MD5_DIGEST_LENGTH]; CC_MD5(str, (CC_LONG)strlen(str), r); NSString *filename = [NSString stringWithFormat:@"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%@", r[0], r[1], r[2], r[3], r[4], r[5], r[6], r[7], r[8], r[9], r[10], r[11], r[12], r[13], r[14], r[15], [key.pathExtension isEqualToString:@""] ? @"" : [NSString stringWithFormat:@".%@", key.pathExtension]]; return filename; } /** 图片缓存目录 @param fullNamespace 自定义子目录名称 @return 完整目录 */ - (nullable NSString *)makeDiskCachePath:(nonnull NSString*)fullNamespace { NSArray<NSString *> *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES); return [paths[0] stringByAppendingPathComponent:fullNamespace]; } #pragma mark - Cache Info /** 磁盘缓存使用的大小 @return 磁盘缓存的大小 */ - (NSUInteger)getSize { __block NSUInteger size = 0; dispatch_sync(self.ioQueue, ^{ NSDirectoryEnumerator *fileEnumerator = [_fileManager enumeratorAtPath:self.diskCachePath]; for (NSString *fileName in fileEnumerator) { NSString *filePath = [self.diskCachePath stringByAppendingPathComponent:fileName]; NSDictionary<NSString *, id> *attrs = [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:nil]; size += [attrs fileSize]; } }); return size; } /** 磁盘缓存的图片数量 @return 缓存的图片数量 */ - (NSUInteger)getDiskCount { __block NSUInteger count = 0; dispatch_sync(self.ioQueue, ^{ NSDirectoryEnumerator *fileEnumerator = [_fileManager enumeratorAtPath:self.diskCachePath]; count = fileEnumerator.allObjects.count; }); return count; } /** 异步计算磁盘缓存的大小 @param completionBlock 回调Block */ - (void)calculateSizeWithCompletionBlock:(nullable SDWebImageCalculateSizeBlock)completionBlock { NSURL *diskCacheURL = [NSURL fileURLWithPath:self.diskCachePath isDirectory:YES]; dispatch_async(self.ioQueue, ^{ NSUInteger fileCount = 0; NSUInteger totalSize = 0; NSDirectoryEnumerator *fileEnumerator = [_fileManager enumeratorAtURL:diskCacheURL includingPropertiesForKeys:@[NSFileSize] options:NSDirectoryEnumerationSkipsHiddenFiles errorHandler:NULL]; for (NSURL *fileURL in fileEnumerator) { NSNumber *fileSize; [fileURL getResourceValue:&fileSize forKey:NSURLFileSizeKey error:NULL]; totalSize += fileSize.unsignedIntegerValue; fileCount += 1; } if (completionBlock) { dispatch_async(dispatch_get_main_queue(), ^{ completionBlock(fileCount, totalSize); }); } }); }
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