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:
- (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:
MYURLCache *cache = [[MYURLCache alloc] init];
[NSURLCache setSharedURLCache:cache];
OK,搞定了,试试webView加载图片吧~