UIWebView的离线缓存
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:
+ (void)setSharedURLCache:(NSURLCache *)cache;
- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request;
- (void)storeCachedResponse:(NSCachedURLResponse *)cachedResponse forRequest:(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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- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request { NSString *pathString = [[request URL] absoluteString]; if (![pathString hasSuffix:@ ".jpg" ]) { return [super cachedResponseForRequest:request]; } if ([[MYURLCache sharedCache] hasDataForURL:pathString]) { NSData *data = [[MYURLCache sharedCache] dataForURL:pathString]; NSURLResponse *response = [[[NSURLResponse alloc] initWithURL:[request URL] MIMEType:@ "image/jpg" expectedContentLength:[data length] textEncodingName:nil] autorelease]; return [[[NSCachedURLResponse alloc] initWithResponse:response data:data] autorelease]; } return [super cachedResponseForRequest:request]; } - ( void )storeCachedResponse:(NSCachedURLResponse *)cachedResponse forRequest:(NSURLRequest *)request { NSString *pathString = [[request URL] absoluteString]; if (![pathString hasSuffix:@ ".jpg" ]) { [super storeCachedResponse:cachedResponse forRequest:request]; return ; } [[MYURLCache sharedCache] storeData:cachedResponse.data forURL:pathString]; } |
上面的代码是专门用来搞定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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MYURLCache *cache = [[MYURLCache alloc] init]; [NSURLCache setSharedURLCache:cache]; |
OK,搞定了,试试webView加载图片吧~
posted on 2015-08-27 14:30 yucaijiang 阅读(300) 评论(0) 编辑 收藏 举报