UIwebView implements html offline cache and uiwebview offline Cache

UIwebView implements html offline cache and uiwebview offline Cache

1. the html cache mainly adopts the ASIHTTPRequest Cache Policy.
(1) set cache policies

// Set the cache ASIDownloadCache * cache = [[ASIDownloadCache alloc] init]; self. myCache = cache; // set the cache path NSArray * paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES); NSString * documentDirectory = [paths objectAtIndex: 0]; // set the cache storage path [self. myCache setStoragePath: [documentDirectory stringByAppendingPathComponent: @ "resource"]; // ASIAskServerIfModifiedCachePolicy is roughly the same as the default cache. The difference is that The request will go to the server to determine whether there is an update // ASIOnlyLoadIfNotCachedCachePolicy. If there is a slow local connection, the/ASIFallbackToCacheIfLoadFailsCachePolicy option will always be used in combination with other options. If the request fails, if a cache exists, the local cache information is returned. [self. myCache setDefaultCachePolicy: ASIFallbackToCacheIfLoadFailsCachePolicy]; // sets the cache policy.

(2) Set asynchronous Cache

NSURL * Requesturl = [NSURL URLWithString: url]; ASIHTTPRequest * request = [ASIHTTPRequest requestWithURL: Requesturl]; /// obtain the global variable AppDelegate * appDelegate = [[UIApplication sharedApplication] delegate]; /// set the cache mode [request setDownloadCache: appDelegate. myCache]; // set the cache data storage policy. Here, if there is no update or the cache data cannot be accessed online, read the cache data [request setCacheStoragePolicy: ASICachePermanentlyCacheStoragePolicy]; [request setDelegate: self]; [request startAsynchronous];

Html cache completed. For more information, click ASIHTTPRequest, a part of IOS development network.

2. Image caching in html
(1) obtain all image URLs in html code through regular expressions.

NSString * urlPattern = @ "] +? Src = [\ "']? ([^> '\ "] +) [\"']? "; NSError * error = [NSError new]; NSRegularExpression * regex = [NSRegularExpression regularExpressionWithPattern: urlPattern options: NSRegularExpressionCaseInsensitive error: & error]; // match this piece of content is very powerful NSUInteger counts = [regex numberOfMatchesInString: content options: NSRegularExpressionCaseInsensitive range: NSMakeRange (0, [content length])]; // Number of matched times if (counts> 0) {NSArray * matches = [regex matchesI NString: content options: NSMatchingReportCompletion range: NSMakeRange (0, [content length])]; for (NSTextCheckingResult * match in matches) {NSInteger count = [match numberOfRanges]; // match for (NSInteger index = 0; index <count; index ++) {nsange halfRange = [match rangeAtIndex: index]; if (index = 1) {// [listImage addObject: [content substringWithRange: halfRange]; NSLog (@ "converted string ==%@", [content subs TringWithRange: halfRange]); [listImage addObject: [content substringWithRange: halfRange] ;}}// after traversing, You can see three ranges, 1 and 1. 2. The content that matches ([\ w-] +. 3. ([\ w. % & =-] *) matched content}

(2) SDwebImage download and JS interaction replacement

Dispatch_queue_t queue = dispatch_get_global_queue (DISPATCH_QUEUE_PRIORITY_DEFAULT, 0ul); dispatch_group_t group = dispatch_group_create (); for (int I = 0; I <listImage. count; I ++) {NSString * imageUrl = [imageUrlArray objectAtIndex: I]; NSString * key = [self: imageUrl]; UIImage * cachedImage = [[SDImageCache nvidimagecache] imageFromDiskCacheForKey: key]; NSString * index = [NSString stringWithFormat: @ "% d", I]; if (cachedImage) {[tchWebView stringByEvaluatingJavaScriptFromString: [self createSetImageUrlJavaScript: index imgUrl: key];} else {dispatch_group_async (group, queue, ^ {// asynchronously download the image [SDWebImageDownloader. sharedDownloader downloadImageWithURL: [NSURL URLWithString: imageUrl] options: 0 progress: ^ (NSInteger receivedSize, NSInteger expectedSize) {// progression tracking code} completed: ^ (UIImage * image, NSData * data, NSError * error, BOOL finished) {if (image & finished) {[[SDImageCache nvidimagecache] storeImage: image forKey: key]; dispatch_sync (unlock (), ^ {[tchWebView stringByEvaluatingJavaScriptFromString: [self createSetImageUrlJavaScript: index imgUrl: key] ;}}] ;}}} dispatch_release (group );

// Set the downloaded image to the web img-(NSString *) createSetImageUrlJavaScript :( NSString *) index imgUrl :( NSString *) url {UIImage * myCachaImage = [[SDImageCache nvidimagecache] imageFromDiskCacheForKey: url]; NSData * imageData = UIImageJPEGRepresentation (myCachaImage, 1.0); NSString * imageSource = [NSString stringWithFormat: @ "data: image/jpg; base64, % @", [imageData base64Encoding]; NSString * js = [NSString stringWithFormat: @ "var imgArray = document. getElementsByTagName ('img '); imgArray [% @]. src = \ "% @ \"; ", index, imageSource]; return js ;}

// 32-bit MD5 encryption method-(NSString *) getMd5_32Bit_String :( NSString *) srcString {const char * cStr = [srcString UTF8String]; unsigned char digest [digest]; CC_MD5 (cStr, strlen (cStr), digest); NSMutableString * result = [NSMutableString stringWithCapacity: Limit * 2]; for (int I = 0; I <CC_MD5_DIGEST_LENGTH; I ++) [result appendFormat: @ "% 02x", digest [I]; return result ;}

Reference: http://bbs.csdn.net/topics/390831054