本博客的原则是：不发则已，要发就发牛逼的。不指望上推荐，只希望发些精髓的东西，与业界的朋友共同成长。
相信不少朋友用过UI
webView，webView下载的图片一般比较大，这个要能缓存就好了，可以大幅度提高加载速度，同时为用户节省流量。本文就是讲如何完美解决webView缓存的问题。
实际上，UIWebView自己是有缓存的，但容量有限，清理时间我们也不好掌握，那它是用什么做的缓存呢？是NSURLCache。看到它有几个方法:
+ ([backcolor=transparent]void)setSharedURLCache:([backcolor=transparent]NSURLCache *)cache;
- ([backcolor=transparent]NSCachedURLResponse *)cachedResponseForRequest:([backcolor=transparent]NSURLRequest *)request;
- ([backcolor=transparent]void)storeCachedResponse:([backcolor=transparent]NSCachedURLResponse *)cachedResponse forRequest:([backcolor=transparent]NSURLRequest *)request;
太好了，我们只要写一个子类继承NSURLCache，实现后两个方法，再让这个子类对象成为sharedURLCache，就可以操控webView的请求和缓存了。抛个砖吧：
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[align=right !important][backcolor=white !important]28 [backcolor=initial !important][backcolor=white !important]- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request {
[backcolor=white !important]
[backcolor=white !important] NSString *pathString = [[request URL] absoluteString];
[backcolor=white !important]
[backcolor=white !important] if (![pathString hasSuffix:@".jpg"]) {
[backcolor=white !important] return [super cachedResponseForRequest:request];
[backcolor=white !important] }
[backcolor=white !important]
[backcolor=white !important] if ([[MYURLCache sharedCache] hasDataForURL:pathString]) {
[backcolor=white !important] NSData *data = [[MYURLCache sharedCache] dataForURL:pathString];
[backcolor=white !important] NSURLResponse *response = [[[NSURLResponse alloc] initWithURL:[request URL]
[backcolor=white !important] MIMEType:@"image/jpg"
[backcolor=white !important] expectedContentLength:[data length]
[backcolor=white !important] textEncodingName:nil] autorelease];
[backcolor=white !important] return [[[NSCachedURLResponse alloc] initWithResponse:response data:data] autorelease];
[backcolor=white !important] }
[backcolor=white !important] return [super cachedResponseForRequest:request];
[backcolor=white !important]}
[backcolor=white !important]
[backcolor=white !important]- (void)storeCachedResponse:(NSCachedURLResponse *)cachedResponse forRequest:(NSURLRequest *)request {
[backcolor=white !important] NSString *pathString = [[request URL] absoluteString];
[backcolor=white !important] if (![pathString hasSuffix:@".jpg"]) {
[backcolor=white !important] [super storeCachedResponse:cachedResponse forRequest:request];
[backcolor=white !important] return;
[backcolor=white !important] }
[backcolor=white !important]
[backcolor=white !important] [[MYURLCache sharedCache] storeData:cachedResponse.data forURL:pathString];
[backcolor=white !important]}
上面的代码[backcolor=transparent]是专门用来搞定webView中的jpg图片的，其中MYURLCache提供了把data读、写入文件的功能，这个不是本文的重点，请各位自己实现吧。
在程序启动的时候，加入以下代码：
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[align=right !important][backcolor=white !important]2 [backcolor=initial !important][backcolor=white !important]MYURLCache *cache = [[MYURLCache alloc] init];
[backcolor=white !important][NSURLCache setSharedURLCache:cache];
OK，搞定了，试试webView加载图片吧~
