SDWebImage源码解析之SDWebImageManager的注解(sdwebimage,sdwebimagemanager,注解,移动开发)

/**ThisfileispartoftheSDWebImagepackage.*(c)OlivierPoitrey**Forthefullcopyrightandlicenseinformation,pleaseviewtheLICENSE*filethatwasdistributedwiththissourcecode.*/#import"SDWebImageCompat.h"#import"SDWebImageOperation.h"#import"SDWebImageDownloader.h"#import"SDImageCache.h"typedefNS_OPTIONS(NSUInteger,SDWebImageOptions){/***Bydefault,whenaURLfailtobedownloaded,theURLisblacklistedsothelibrarywon'tkeeptrying.*Thisflagdisablethisblacklisting.*//***默认情况下,如果一个url在下载的时候失败了,那么这个url会被加入黑名单并且library不会尝试再次下载,这个flag会阻止library把失败的url加入黑名单(简单来说如果选择了这个flag,那么即使某个url下载失败了,sdwebimage还是会尝试再次下载他.)*/SDWebImageRetryFailed=1<<0,/***Bydefault,imagedownloadsarestartedduringUIinteractions,thisflagsdisablethisfeature,*leadingtodelayeddownloadonUIScrollViewdecelerationforinstance.*//***默认情况下,图片会在交互发生的时候下载(例如你滑动tableview的时候),这个flag会禁止这个特性,导致的结果就是在scrollview减速的时候*才会开始下载(也就是你滑动的时候scrollview不下载,你手从屏幕上移走,scrollview开始减速的时候才会开始下载图片)*/SDWebImageLowPriority=1<<1,/***Thisflagdisableson-diskcaching*//**这个flag禁止磁盘缓存,只有内存缓存*/SDWebImageCacheMemoryOnly=1<<2,/***Thisflagenablesprogressivedownload,theimageisdisplayedprogressivelyduringdownloadasabrowserwoulddo.*Bydefault,theimageisonlydisplayedoncecompletelydownloaded.*//**这个flag会在图片下载的时候就显示(就像你用浏览器浏览网页的时候那种图片下载,一截一截的显示(待确认))**/SDWebImageProgressiveDownload=1<<3,/***Eveniftheimageiscached,respecttheHTTPresponsecachecontrol,andrefreshtheimagefromremotelocationifneeded.*ThediskcachingwillbehandledbyNSURLCacheinsteadofSDWebImageleadingtoslightperformancedegradation.*ThisoptionhelpsdealwithimageschangingbehindthesamerequestURL,e.g.Facebookgraphapiprofilepics.*Ifacachedimageisrefreshed,thecompletionblockiscalledoncewiththecachedimageandagainwiththefinalimage.**Usethisflagonlyifyoucan'tmakeyourURLsstaticwithembededcachebustingparameter.*//**这个选项的意思看的不是很懂,大意是即使一个图片缓存了,还是会重新请求.并且缓存侧略依据NSURLCache而不是SDWebImage.**/SDWebImageRefreshCached=1<<4,/***IniOS4+,continuethedownloadoftheimageiftheappgoestobackground.Thisisachievedbyaskingthesystemfor*extratimeinbackgroundtolettherequestfinish.Ifthebackgroundtaskexpirestheoperationwillbecancelled.*//**启动后台下载,加入你进入一个页面,有一张图片正在下载这时候你让app进入后台,图片还是会继续下载(这个估计要开backgroundfetch才有用)*/SDWebImageContinueInBackground=1<<5,/***HandlescookiesstoredinNSHTTPCookieStorebysetting*NSMutableURLRequest.HTTPShouldHandleCookies=YES;*//**可以控制存在NSHTTPCookieStore的cookies.(我没用过,等用过的人过来解释一下)*/SDWebImageHandleCookies=1<<6,/***EnabletoallowuntrustedSSLceriticates.*Usefulfortestingpurposes.Usewithcautioninproduction.*//**允许不安全的SSL证书,在正式环境中慎用*/SDWebImageAllowInvalidSSLCertificates=1<<7,/***Bydefault,imageareloadedintheordertheywerequeued.Thisflagmovethemto*thefrontofthequeueandisloadedimmediatelyinsteadofwaitingforthecurrentqueuetobeloaded(which*couldtakeawhile).*//**默认情况下,image在装载的时候是按照他们在队列中的顺序装载的(就是先进先出).这个flag会把他们移动到队列的前端,并且立刻装载*而不是等到当前队列装载的时候再装载.*/SDWebImageHighPriority=1<<8,/***Bydefault,placeholderimagesareloadedwhiletheimageisloading.Thisflagwilldelaytheloading*oftheplaceholderimageuntilaftertheimagehasfinishedloading.*//**默认情况下,占位图会在图片下载的时候显示.这个flag开启会延迟占位图显示的时间,等到图片下载完成之后才会显示占位图.(等图片显示完了我干嘛还显示占位图?或许是我理解错了?)*/SDWebImageDelayPlaceholder=1<<9,/***Weusuallydon'tcalltransformDownloadedImagedelegatemethodonanimatedimages,*asmosttransformationcodewouldmangleit.*Usethisflagtotransformthemanyway.*//**是否transform图片(没用过,还要再看,但是据我估计,是否是图片有可能方向不对需要调整方向,例如采用iPhone拍摄的照片如果不纠正方向,那么图片是向左旋转90度的.可能很多人不知道iPhone的摄像头并不是竖直的,而是向左偏了90度.具体请google.)*/SDWebImageTransformAnimatedImage=1<<10,};typedefvoid(^SDWebImageCompletionBlock)(UIImage*image,NSError*error,SDImageCacheTypecacheType,NSURL*imageURL);typedefvoid(^SDWebImageCompletionWithFinishedBlock)(UIImage*image,NSError*error,SDImageCacheTypecacheType,BOOLfinished,NSURL*imageURL);typedefNSString*(^SDWebImageCacheKeyFilterBlock)(NSURL*url);@classSDWebImageManager;@protocolSDWebImageManagerDelegate@optional/***Controlswhichimageshouldbedownloadedwhentheimageisnotfoundinthecache.**@paramimageManagerThecurrent`SDWebImageManager`*@paramimageURLTheurloftheimagetobedownloaded**@returnReturnNOtopreventthedownloadingoftheimageoncachemisses.Ifnotimplemented,YESisimplied.*//**主要作用是当缓存里没有发现某张图片的缓存时,是否选择下载这张图片(默认是yes),可以选择no,那么sdwebimage在缓存中没有找到这张图片的时候不会选择下载*/-(BOOL)imageManager:(SDWebImageManager*)imageManagershouldDownloadImageForURL:(NSURL*)imageURL;/***Allowstotransformtheimageimmediatelyafterithasbeendownloadedandjustbeforetocacheitondiskandmemory.*NOTE:Thismethodiscalledfromaglobalqueueinordertonottoblockthemainthread.**@paramimageManagerThecurrent`SDWebImageManager`*@paramimageTheimagetotransform*@paramimageURLTheurloftheimagetotransform**@returnThetransformedimageobject.*//***在图片下载完成并且还没有加入磁盘缓存或者内存缓存的时候就transform这个图片.这个方法是在异步线程执行的,防治阻塞主线程.*至于为什么在异步执行很简单,对一张图片纠正方向(也就是transform)是很耗资源的,一张2M大小的图片纠正方向你可以用instrument测试一下耗时.*很恐怖*/-(UIImage*)imageManager:(SDWebImageManager*)imageManagertransformDownloadedImage:(UIImage*)imagewithURL:(NSURL*)imageURL;@end/***TheSDWebImageManageristheclassbehindtheUIImageView+WebCachecategoryandlikes.*Ittiestheasynchronousdownloader(SDWebImageDownloader)withtheimagecachestore(SDImageCache).*Youcanusethisclassdirectlytobenefitfromwebimagedownloadingwithcachinginanothercontextthan*aUIView.**HereisasimpleexampleofhowtouseSDWebImageManager:**@codeSDWebImageManager*manager=[SDWebImageManagersharedManager];[managerdownloadImageWithURL:imageURLoptions:0progress:nilcompleted:^(UIImage*image,NSError*error,SDImageCacheTypecacheType,BOOLfinished,NSURL*imageURL){if(image){//dosomethingwithimage}}];*@endcode*//**这一段是阐述SDWebImageManager是干嘛的.其实UIImageView+WebCache这个category背后执行操作的就是这个SDWebImageManager.他会绑定一个下载器也就是SDWebImageDownloader和一个缓存SDImageCache.后面的大意应该是讲你可以直接使用一个其他上下文环境的SDWebImageManager,而不是仅仅限于一个UIView.*/@interfaceSDWebImageManager:NSObject@property(weak,nonatomic)iddelegate;/***如同上文所说,一个SDWebImageManager会绑定一个imageCache和一个下载器.*/@property(strong,nonatomic,readonly)SDImageCache*imageCache;@property(strong,nonatomic,readonly)SDWebImageDownloader*imageDownloader;/***ThecachefilterisablockusedeachtimeSDWebImageManagerneedtoconvertanURLintoacachekey.Thiscan*beusedtoremovedynamicpartofanimageURL.**Thefollowingexamplesetsafilterintheapplicationdelegatethatwillremoveanyquery-stringfromthe*URLbeforetouseitasacachekey:**@code[[SDWebImageManagersharedManager]setCacheKeyFilter:^(NSURL*url){url=[[NSURLalloc]initWithScheme:url.schemehost:url.hostpath:url.path];return[urlabsoluteString];}];*@endcode*//**这个cacheKeyFilter是干嘛的呢?很简单.1他是一个block.2.这个block的作用就是生成一个image的key.因为sdwebimage的缓存原理你可以当成是一个字典,每一个字典的value就是一张image,那么这个value对应的key是什么呢?就是cacheKeyFilter根据某个规则对这个图片的url做一些操作生成的.上面的示例就显示了怎么利用这个block把image的url重新组合生成一个key.以后当sdwebimage检测到你*/@property(nonatomic,copy)SDWebImageCacheKeyFilterBlockcacheKeyFilter;/***ReturnsglobalSDWebImageManagerinstance.**@returnSDWebImageManagersharedinstance*//**这个不用我解释了吧,生成一个SDWebImagemanager的单例.*/+(SDWebImageManager*)sharedManager;/***DownloadstheimageatthegivenURLifnotpresentincacheorreturnthecachedversionotherwise.*从给定的URL中下载一个之前没有被缓存的Image.**@paramurlTheURLtotheimage*@paramoptionsAmasktospecifyoptionstouseforthisrequest*@paramprogressBlockAblockcalledwhileimageisdownloading*@paramcompletedBlockAblockcalledwhenoperationhasbeencompleted.**Thisparameterisrequired.**ThisblockhasnoreturnvalueandtakestherequestedUIImageasfirstparameter.*IncaseoferrortheimageparameterisnilandthesecondparametermaycontainanNSError.**Thethirdparameterisan`SDImageCacheType`enumindicatingiftheimagewasretrivedfromthelocalcache*orfromthememorycacheorfromthenetwork.**ThelastparameterissettoNOwhentheSDWebImageProgressiveDownloadoptionisusedandtheimageis*downloading.Thisblockisthuscalledrepetidlywithapartialimage.Whenimageisfullydownloaded,the*blockiscalledalasttimewiththefullimageandthelastparametersettoYES.**@returnReturnsanNSObjectconformingtoSDWebImageOperation.ShouldbeaninstanceofSDWebImageDownloaderOperation*//**这个方法主要就是SDWebImage下载图片的方法了.*第一个参数是必须要的,就是image的url*第二个参数就是我们上面的Options,你可以定制化各种各样的操作.详情参上.*第三个参数是一个回调block,用于图片在下载过程中的回调.(英文注释应该是有问题的.)*第四个参数是一个下载完成的回调.会在图片下载完成后回调.*返回值是一个NSObject类,并且这个NSObject类是conforming一个协议这个协议叫做SDWebImageOperation,这个协议很简单,就是一个cancel掉operation的协议.*/-(id)downloadImageWithURL:(NSURL*)urloptions:(SDWebImageOptions)optionsprogress:(SDWebImageDownloaderProgressBlock)progressBlockcompleted:(SDWebImageCompletionWithFinishedBlock)completedBlock;/***SavesimagetocacheforgivenURL**@paramimageTheimagetocache*@paramurlTheURLtotheimage**//**将图片存入cache的方法,类似于字典的setValue:forKey:*/-(void)saveImageToCache:(UIImage*)imageforURL:(NSURL*)url;/***Cancelallcurrentopreations*//**取消掉当前所有的下载图片的operation*/-(void)cancelAll;/***Checkoneormoreoperationsrunning*//**check一下是否有一个或者多个operation正在执行(简单来说就是check是否有图片在下载)*/-(BOOL)isRunning;/***Checkifimagehasalreadybeencached**@paramurlimageurl**@returniftheimagewasalreadycached*//**通过一个image的url是否已经存在,如果存在返回yes,否则返回no*/-(BOOL)cachedImageExistsForURL:(NSURL*)url;/***Checkifimagehasalreadybeencachedondiskonly**@paramurlimageurl**@returniftheimagewasalreadycached(diskonly)*//**检测一个image是否已经被缓存到磁盘(是否存且仅存在disk里).*/-(BOOL)diskImageExistsForURL:(NSURL*)url;/***Asynccheckifimagehasalreadybeencached**@paramurlimageurl*@paramcompletionBlocktheblocktobeexecutedwhenthecheckisfinished**@notethecompletionblockisalwaysexecutedonthemainqueue*//**如果检测到图片已经被缓存,那么执行回调block.这个block会永远执行在主线程.也就是你可以在这个回调block里更新ui.*/-(void)cachedImageExistsForURL:(NSURL*)urlcompletion:(SDWebImageCheckCacheCompletionBlock)completionBlock;/***Asynccheckifimagehasalreadybeencachedondiskonly**@paramurlimageurl*@paramcompletionBlocktheblocktobeexecutedwhenthecheckisfinished**@notethecompletionblockisalwaysexecutedonthemainqueue*//**如果检测到图片已经被缓存在磁盘(存且仅存在disk),那么执行回调block.这个block会永远执行在主线程.也就是你可以在这个回调block里更新ui.*/-(void)diskImageExistsForURL:(NSURL*)urlcompletion:(SDWebImageCheckCacheCompletionBlock)completionBlock;/***ReturnthecachekeyforagivenURL*//**通过image的url返回image存在缓存里的key.有人会问了,为什么不直接把图片的url当做image的key来使用呢?而是非要对url做一些处理才能当做key.我的解释是,我也不太清楚.可能为了防止重复吧.*/-(NSString*)cacheKeyForURL:(NSURL*)url;@end#pragmamark-Deprecatedtypedefvoid(^SDWebImageCompletedBlock)(UIImage*image,NSError*error,SDImageCacheTypecacheType)__deprecated_msg("Blocktypedeprecated.Use`SDWebImageCompletionBlock`");typedefvoid(^SDWebImageCompletedWithFinishedBlock)(UIImage*image,NSError*error,SDImageCacheTypecacheType,BOOLfinished)__deprecated_msg("Blocktypedeprecated.Use`SDWebImageCompletionWithFinishedBlock`");//已被废弃@interfaceSDWebImageManager(Deprecated)/***DownloadstheimageatthegivenURLifnotpresentincacheorreturnthecachedversionotherwise.**@deprecatedThismethodhasbeendeprecated.Use`downloadImageWithURL:options:progress:completed:`*/-(id)downloadWithURL:(NSURL*)urloptions:(SDWebImageOptions)optionsprogress:(SDWebImageDownloaderProgressBlock)progressBlockcompleted:(SDWebImageCompletedWithFinishedBlock)completedBlock__deprecated_msg("Methoddeprecated.Use`downloadImageWithURL:options:progress:completed:`");@end

/**ThisfileispartoftheSDWebImagepackage.*(c)OlivierPoitrey**Forthefullcopyrightandlicenseinformation,pleaseviewtheLICENSE*filethatwasdistributedwiththissourcecode.*/#import"SDWebImageManager.h"#import//内部类.@interfaceSDWebImageCombinedOperation:NSObject@property(assign,nonatomic,getter=isCancelled)BOOLcancelled;@property(copy,nonatomic)SDWebImageNoParamsBlockcancelBlock;@property(strong,nonatomic)NSOperation*cacheOperation;@end@interfaceSDWebImageManager()@property(strong,nonatomic,readwrite)SDImageCache*imageCache;@property(strong,nonatomic,readwrite)SDWebImageDownloader*imageDownloader;@property(strong,nonatomic)NSMutableSet*failedURLs;@property(strong,nonatomic)NSMutableArray*runningOperations;@end@implementationSDWebImageManager//利用disptach_once特性生成一个单例,用烂了的方法.不赘述.+(id)sharedManager{staticdispatch_once_tonce;staticidinstance;dispatch_once(&once,^{instance=[selfnew];});returninstance;}//初始化方法.//1.获得一个SDImageCache的单例.2.获取一个SDWebImageDownloader的单例.3.新建一个MutableSet来存储下载失败的url.//4.新建一个用来存储下载operation的可变数组.//为什么不用MutableArray储存下载失败的URL?//因为NSSet类有一个特性,就是Hash.实际上NSSet是一个哈希表,哈希表比数组优秀的地方是什么呢?就是查找速度快.查找同样一个元素,哈希表只需要通过key//即可取到,而数组至少需要遍历依次.因为SDWebImage里有关失败URL的业务需求是,一个失败的URL只需要储存一次.这样的话Set自然比Array更合适.-(id)init{if((self=[superinit])){_imageCache=[selfcreateCache];_imageDownloader=[SDWebImageDownloadersharedDownloader];_failedURLs=[NSMutableSetnew];_runningOperations=[NSMutableArraynew];}returnself;}//获取一个cache的单例-(SDImageCache*)createCache{return[SDImageCachesharedImageCache];}//利用Image的URL生成一个缓存时需要的key.//这里有两种情况,第一种是如果检测到cacheKeyFilter不为空时,利用cacheKeyFilter来处理URL生成一个key.//如果为空,那么直接返回URL的string内容,当做key.-(NSString*)cacheKeyForURL:(NSURL*)url{if(self.cacheKeyFilter){returnself.cacheKeyFilter(url);}else{return[urlabsoluteString];}}//检测一张图片是否已被缓存.//首先检测内存缓存是否存在这张图片,如果已有,直接返回yes.//如果内存缓存里没有这张图片,那么调用diskImageExistsWithKey这个方法去硬盘缓存里找-(BOOL)cachedImageExistsForURL:(NSURL*)url{NSString*key=[selfcacheKeyForURL:url];if([self.imageCacheimageFromMemoryCacheForKey:key]!=nil)returnYES;return[self.imageCachediskImageExistsWithKey:key];}//检测硬盘里是否缓存了图片-(BOOL)diskImageExistsForURL:(NSURL*)url{NSString*key=[selfcacheKeyForURL:url];return[self.imageCachediskImageExistsWithKey:key];}//首先生成一个用来cache住Image的key(利用key的url生成)//然后检测内存缓存里是否已经有这张图片//如果已经被缓存,那么再主线程里回调block//如果没有检测到,那么调用diskImageExistsWithKey,这个方法会在异步线程里,将图片存到硬盘,当然在存图之前也会检测是否已在硬盘缓存图片.-(void)cachedImageExistsForURL:(NSURL*)urlcompletion:(SDWebImageCheckCacheCompletionBlock)completionBlock{NSString*key=[selfcacheKeyForURL:url];BOOLisInMemoryCache=([self.imageCacheimageFromMemoryCacheForKey:key]!=nil);if(isInMemoryCache){//makingsurewecallthecompletionblockonthemainqueuedispatch_async(dispatch_get_main_queue(),^{if(completionBlock){completionBlock(YES);}});return;}[self.imageCachediskImageExistsWithKey:keycompletion:^(BOOLisInDiskCache){//thecompletionblockofcheckDiskCacheForImageWithKey:completion:isalwayscalledonthemainqueue,noneedtofurtherdispatchif(completionBlock){completionBlock(isInDiskCache);}}];}//将图片存入硬盘-(void)diskImageExistsForURL:(NSURL*)urlcompletion:(SDWebImageCheckCacheCompletionBlock)completionBlock{NSString*key=[selfcacheKeyForURL:url];[self.imageCachediskImageExistsWithKey:keycompletion:^(BOOLisInDiskCache){//thecompletionblockofcheckDiskCacheForImageWithKey:completion:isalwayscalledonthemainqueue,noneedtofurtherdispatchif(completionBlock){completionBlock(isInDiskCache);}}];}//通过url建立一个operation用来下载图片.-(id)downloadImageWithURL:(NSURL*)urloptions:(SDWebImageOptions)optionsprogress:(SDWebImageDownloaderProgressBlock)progressBlockcompleted:(SDWebImageCompletionWithFinishedBlock)completedBlock{//InvokingthismethodwithoutacompletedBlockispointlessNSAssert(completedBlock!=nil,@"Ifyoumeantoprefetchtheimage,use-[SDWebImagePrefetcherprefetchURLs]instead");//VerycommonmistakeistosendtheURLusingNSStringobjectinsteadofNSURL.Forsomestrangereason,XCodewon't//throwanywarningforthistypemismatch.HerewefailsafethiserrorbyallowingURLstobepassedasNSString.if([urlisKindOfClass:NSString.class]){url=[NSURLURLWithString:(NSString*)url];}//PreventsappcrashingonargumenttypeerrorlikesendingNSNullinsteadofNSURLif(![urlisKindOfClass:NSURL.class]){url=nil;}__blockSDWebImageCombinedOperation*operation=[SDWebImageCombinedOperationnew];__weakSDWebImageCombinedOperation*weakOperation=operation;BOOLisFailedUrl=NO;//创建一个互斥锁防止现在有别的线程修改failedURLs.//判断这个url是否是fail过的.如果urlfailed过的那么isFailedUrl就是true@synchronized(self.failedURLs){isFailedUrl=[self.failedURLscontainsObject:url];}//如果url不存在那么直接返回一个block,如果url存在.那么继续进行判断.//options与SDWebImageRetryFailed这个option进行按位与操作.判断用户的options里是否有retry这个option.//如果用户的options里没有retry这个选项并且isFaileUrl是true.那么就回调一个error的block.if(!url||(!(options&SDWebImageRetryFailed)&&isFailedUrl)){dispatch_main_sync_safe(^{NSError*error=[NSErrorerrorWithDomain:NSURLErrorDomaincode:NSURLErrorFileDoesNotExistuserInfo:nil];completedBlock(nil,error,SDImageCacheTypeNone,YES,url);});returnoperation;}//创建一个互斥锁防止现在有别的线程修改runningOperations.@synchronized(self.runningOperations){[self.runningOperationsaddObject:operation];}NSString*key=[selfcacheKeyForURL:url];//cacheOperation应该是一个用来下载图片并且缓存的operationoperation.cacheOperation=[self.imageCachequeryDiskCacheForKey:keydone:^(UIImage*image,SDImageCacheTypecacheType){//判断operation这时候有没有执行cancel操作,如果cancel掉了就把这个operation从我们的operation数组里remove掉然后returnif(operation.isCancelled){@synchronized(self.runningOperations){[self.runningOperationsremoveObject:operation];}return;}if((!image||options&SDWebImageRefreshCached)&&(![self.delegaterespondsToSelector:@selector(imageManager:shouldDownloadImageForURL:)]||[self.delegateimageManager:selfshouldDownloadImageForURL:url])){if(image&&options&SDWebImageRefreshCached){dispatch_main_sync_safe(^{//IfimagewasfoundinthecachebugSDWebImageRefreshCachedisprovided,notifyaboutthecachedimage//ANDtrytore-downloaditinordertoletachancetoNSURLCachetorefreshitfromserver.completedBlock(image,nil,cacheType,YES,url);});}//downloadifnoimageorrequestedtorefreshanyway,anddownloadallowedbydelegate//下面都是判断我们的options里包含哪些SDWebImageOptions,然后给我们的downloaderOptions相应的添加对应的SDWebImageDownloaderOptions.downloaderOptions|=SDWebImageDownloaderLowPriority这种表达式的意思等同于//downloaderOptions=downloaderOptions|SDWebImageDownloaderLowPrioritySDWebImageDownloaderOptionsdownloaderOptions=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(image&&options&SDWebImageRefreshCached){//forceprogressiveoffifimagealreadycachedbutforcedrefreshingdownloaderOptions&=~SDWebImageDownloaderProgressiveDownload;//ignoreimagereadfromNSURLCacheifimageifcachedbutforcerefreshingdownloaderOptions|=SDWebImageDownloaderIgnoreCachedResponse;}//调用imageDownloader去下载image并且返回执行这个request的download的operationidsubOperation=[self.imageDownloaderdownloadImageWithURL:urloptions:downloaderOptionsprogress:progressBlockcompleted:^(UIImage*downloadedImage,NSData*data,NSError*error,BOOLfinished){if(weakOperation.isCancelled){//Donothingiftheoperationwascancelled//See#699formoredetails//ifwewouldcallthecompletedBlock,therecouldbearaceconditionbetweenthisblockandanothercompletedBlockforthesameobject,soifthisoneiscalledsecond,wewilloverwritethenewdata}elseif(error){dispatch_main_sync_safe(^{if(!weakOperation.isCancelled){completedBlock(nil,error,SDImageCacheTypeNone,finished,url);}});if(error.code!=NSURLErrorNotConnectedToInternet&&error.code!=NSURLErrorCancelled&&error.code!=NSURLErrorTimedOut){@synchronized(self.failedURLs){[self.failedURLsaddObject:url];}}}else{if((options&SDWebImageRetryFailed)){@synchronized(self.failedURLs){[self.failedURLsremoveObject:url];}}BOOLcacheOnDisk=!(options&SDWebImageCacheMemoryOnly);if(options&SDWebImageRefreshCached&&image&&!downloadedImage){//ImagerefreshhittheNSURLCachecache,donotcallthecompletionblock}elseif(downloadedImage&&(!downloadedImage.images||(options&SDWebImageTransformAnimatedImage))&&[self.delegaterespondsToSelector:@selector(imageManager:transformDownloadedImage:withURL:)]){dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,0),^{UIImage*transformedImage=[self.delegateimageManager:selftransformDownloadedImage:downloadedImagewithURL:url];if(transformedImage&&finished){BOOLimageWasTransformed=![transformedImageisEqual:downloadedImage];[self.imageCachestoreImage:transformedImagerecalculateFromImage:imageWasTransformedimageData:dataforKey:keytoDisk:cacheOnDisk];}dispatch_main_sync_safe(^{if(!weakOperation.isCancelled){completedBlock(transformedImage,nil,SDImageCacheTypeNone,finished,url);}});});}else{if(downloadedImage&&finished){[self.imageCachestoreImage:downloadedImagerecalculateFromImage:NOimageData:dataforKey:keytoDisk:cacheOnDisk];}dispatch_main_sync_safe(^{if(!weakOperation.isCancelled){completedBlock(downloadedImage,nil,SDImageCacheTypeNone,finished,url);}});}}if(finished){@synchronized(self.runningOperations){[self.runningOperationsremoveObject:operation];}}}];operation.cancelBlock=^{[subOperationcancel];@synchronized(self.runningOperations){[self.runningOperationsremoveObject:weakOperation];}};}elseif(image){dispatch_main_sync_safe(^{if(!weakOperation.isCancelled){completedBlock(image,nil,cacheType,YES,url);}});@synchronized(self.runningOperations){[self.runningOperationsremoveObject:operation];}}else{//Imagenotincacheanddownloaddisallowedbydelegatedispatch_main_sync_safe(^{if(!weakOperation.isCancelled){completedBlock(nil,nil,SDImageCacheTypeNone,YES,url);}});@synchronized(self.runningOperations){[self.runningOperationsremoveObject:operation];}}}];returnoperation;}-(void)saveImageToCache:(UIImage*)imageforURL:(NSURL*)url{if(image&&url){NSString*key=[selfcacheKeyForURL:url];[self.imageCachestoreImage:imageforKey:keytoDisk:YES];}}//cancel掉所有正在执行的operation-(void)cancelAll{@synchronized(self.runningOperations){NSArray*copiedOperations=[self.runningOperationscopy];[copiedOperationsmakeObjectsPerformSelector:@selector(cancel)];[self.runningOperationsremoveObjectsInArray:copiedOperations];}}//判断是否有正在运行的operation-(BOOL)isRunning{returnself.runningOperations.count>0;}@end@implementationSDWebImageCombinedOperation-(void)setCancelBlock:(SDWebImageNoParamsBlock)cancelBlock{//checkiftheoperationisalreadycancelled,thenwejustcallthecancelBlockif(self.isCancelled){if(cancelBlock){cancelBlock();}_cancelBlock=nil;//don'tforgettonilthecancelBlock,otherwisewewillgetcrashes}else{_cancelBlock=[cancelBlockcopy];}}-(void)cancel{self.cancelled=YES;if(self.cacheOperation){[self.cacheOperationcancel];self.cacheOperation=nil;}if(self.cancelBlock){self.cancelBlock();//TODO:thisisatemporaryfixto#809.//Untilwecanfiguretheexactcauseofthecrash,goingwiththeivarinsteadofthesetter//self.cancelBlock=nil;_cancelBlock=nil;}}@end@implementationSDWebImageManager(Deprecated)//deprecatedmethod,usesthenondeprecatedmethod//adapterforthecompletionblock-(id)downloadWithURL:(NSURL*)urloptions:(SDWebImageOptions)optionsprogress:(SDWebImageDownloaderProgressBlock)progressBlockcompleted:(SDWebImageCompletedWithFinishedBlock)completedBlock{return[selfdownloadImageWithURL:urloptions:optionsprogress:progressBlockcompleted:^(UIImage*image,NSError*error,SDImageCacheTypecacheType,BOOLfinished,NSURL*imageURL){if(completedBlock){completedBlock(image,error,cacheType,finished);}}];}@end

typedefNS_ENUM(NSInteger,UIViewAnimationTransition){UIViewAnimationTransitionNone,UIViewAnimationTransitionFlipFromLeft,UIViewAnimationTransitionFlipFromRight,UIViewAnimationTransitionCurlUp,UIViewAnimationTransitionCurlDown,};

typedefNS_OPTIONS(NSUInteger,UIViewAutoresizing){UIViewAutoresizingNone=0,UIViewAutoresizingFlexibleLeftMargin=1<<0,UIViewAutoresizingFlexibleWidth=1<<1,UIViewAutoresizingFlexibleRightMargin=1<<2,UIViewAutoresizingFlexibleTopMargin=1<<3,UIViewAutoresizingFlexibleHeight=1<<4,UIViewAutoresizingFlexibleBottomMargin=1<<5};

UIViewAutoresizingFlexibleLeftMargin=00000001UIViewAutoresizingFlexibleWidth=00000010UIViewAutoresizingFlexibleRightMargin=00000100所以根据上面的表达式,我们的autoResizings=00000111.

00000111&00000001结果就是00000001,为true.表示含有这个选项.

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