我知道最近在 iphone sdk 中引入了一些缓存类，并且还有一个来自three20 的库的 TTURLRequest，可以让您缓存对 URL 的请求。但是，因为我是通过调用 UIWebView 的 loadRequest 在 UIWebView 中加载网页，所以这些技术并不真正适用。
有什么想法可以保存网页，以便在下一次应用启动时，我不必再次从网络上获取整个页面？页面本身已经有一些自动更新自身部分的 ajax 机制。
【问题讨论】：
标签： html ios iphone url uiwebview
您可以将 HTML 保存在文档目录中，并在启动时直接从文档目录加载页面。
要保存 webview 内容： Reading HTML content from a UIWebView
加载：
NSString* path = [[NSBundle mainBundle] pathForResource:@"about" ofType:@"html"];
NSURL* url = [NSURL fileURLWithPath:path];
NSURLRequest* request = [NSURLRequest requestWithURL:url];
[webView loadRequest:request];
【讨论】：
如果页面已经有 AJAX，为什么不将 JavaScript/HTML 存储在应用程序包中以启动，而不是在第一次启动时下载它？然后使用 Corey 在下面给出的代码加载页面，让 AJAX 处理访问网络以获取页面的更新部分。
【讨论】：
关于 UIWebView 的缓存工作方式的文章有很多，总体感觉是，即使某些机制在 MacOS X 下似乎可以正常工作，但相同的方法在 iPhone 下可能会有奇怪的行为。
但是，我正在通过使用由任何NSURLConnection、UIWebView 访问的全局缓存来做到这一点。 就我而言，它有效;)。
你需要了解的是全局流：
loadRequest UIWebView
NSURLCache 询问“是否为此请求缓存了某些内容？”：- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request从那以后，这是我在磁盘上处理缓存的方法，在我这边，以加快 UIWebView 的加载：
NSURLCache 并覆盖对 -(NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request 选择器的 get 控制现在是代码：
@interface MyCache : NSURLCache {
}
@end
@implementation MyCache
-(NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSLog(@"CACHE REQUEST S%@", request);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSArray* tokens = [request.URL.relativePath componentsSeparatedByString:@"/"];
if (tokens==nil) {
NSLog(@"ignoring cache for %@", request);
return nil;
}
NSString* pathWithoutRessourceName=@"";
for (int i=0; i<[tokens count]-1; i++) {
pathWithoutRessourceName = [pathWithoutRessourceName stringByAppendingString:[NSString stringWithFormat:@"%@%@", [tokens objectAtIndex:i], @"/"]];
}
NSString* absolutePath = [NSString stringWithFormat:@"%@%@", documentsDirectory, pathWithoutRessourceName];
NSString* absolutePathWithRessourceName = [NSString stringWithFormat:@"%@%@", documentsDirectory, request.URL.relativePath];
NSString* ressourceName = [absolutePathWithRessourceName stringByReplacingOccurrencesOfString:absolutePath withString:@""];
NSCachedURLResponse* cacheResponse = nil;
//we're only caching .png, .js, .cgz, .jgz
if (
[ressourceName rangeOfString:@".png"].location!=NSNotFound ||
[ressourceName rangeOfString:@".js"].location!=NSNotFound ||
[ressourceName rangeOfString:@".cgz"].location!=NSNotFound ||
[ressourceName rangeOfString:@".jgz"].location!=NSNotFound) {
NSString* storagePath = [NSString stringWithFormat:@"%@/myCache%@", documentsDirectory, request.URL.relativePath];
//this ressource is candidate for cache.
NSData* content;
NSError* error = nil;
//is it already cached ?
if ([[NSFileManager defaultManager] fileExistsAtPath:storagePath]) {
//NSLog(@"CACHE FOUND for %@", request.URL.relativePath);
content = [[NSData dataWithContentsOfFile:storagePath] retain];
NSURLResponse* response = [[NSURLResponse alloc] initWithURL:request.URL MIMEType:@"" expectedContentLength:[content length] textEncodingName:nil];
cacheResponse = [[NSCachedURLResponse alloc] initWithResponse:response data:content];
} else {
//trick here : if no cache, populate it asynchronously and return nil
[NSThread detachNewThreadSelector:@selector(populateCacheFor:) toTarget:self withObject:request];
}
} else {
NSLog(@"ignoring cache for %@", request);
}
return cacheResponse;
}
-(void)populateCacheFor:(NSURLRequest*)request {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
//NSLog(@"PATH S%@", paths);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSArray* tokens = [request.URL.relativePath componentsSeparatedByString:@"/"];
NSString* pathWithoutRessourceName=@"";
for (int i=0; i<[tokens count]-1; i++) {
pathWithoutRessourceName = [pathWithoutRessourceName stringByAppendingString:[NSString stringWithFormat:@"%@%@", [tokens objectAtIndex:i], @"/"]];
}
NSString* absolutePath = [NSString stringWithFormat:@"%@/myCache%@", documentsDirectory, pathWithoutRessourceName];
//NSString* absolutePathWithRessourceName = [NSString stringWithFormat:@"%@%@", documentsDirectory, request.URL.relativePath];
//NSString* ressourceName = [absolutePathWithRessourceName stringByReplacingOccurrencesOfString:absolutePath withString:@""];
NSString* storagePath = [NSString stringWithFormat:@"%@/myCache%@", documentsDirectory, request.URL.relativePath];
NSData* content;
NSError* error = nil;
NSCachedURLResponse* cacheResponse = nil;
NSLog(@"NO CACHE FOUND for %@", request.URL);
//NSLog(@"retrieving content (timeout=%f) for %@ ...", [request timeoutInterval], request.URL);
content = [NSData dataWithContentsOfURL:request.URL options:1 error:&error];
//NSLog(@"content retrieved for %@ / error:%@", request.URL, error);
if (error!=nil) {
NSLog(@"ERROR %@ info:%@", error, error.userInfo);
NSLog(@"Cache not populated for %@", request.URL);
} else {
NSURLResponse* response = [[NSURLResponse alloc] initWithURL:request.URL MIMEType:@"" expectedContentLength:[content length] textEncodingName:nil];
cacheResponse = [[NSCachedURLResponse alloc] initWithResponse:response data:content];
//the store is invoked automatically.
[[NSFileManager defaultManager] createDirectoryAtPath:absolutePath withIntermediateDirectories:YES attributes:nil error:&error];
BOOL ok;// = [[NSFileManager defaultManager] createDirectoryAtPath:absolutePath withIntermediateDirectories:YES attributes:nil error:&error];
ok = [content writeToFile:storagePath atomically:YES];
NSLog(@"Caching %@ : %@", storagePath , ok?@"OK":@"KO");
}
[pool release];
}
@end
以及在您的应用程序中使用它：
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* documentsDirectory = [paths objectAtIndex:0];
NSString* diskCachePath = [NSString stringWithFormat:@"%@/%@", documentsDirectory, @"myCache"];
NSError* error;
[[NSFileManager defaultManager] createDirectoryAtPath:diskCachePath withIntermediateDirectories:YES attributes:nil error:&error];
MyCache* cacheMngr = [[MyCache alloc] initWithMemoryCapacity:10000 diskCapacity:100000000 diskPath:diskCachePath];
[NSURLCache setSharedURLCache:cacheMngr];
这段代码值得大量清理。但主要的东西应该在那里。我在完成这项工作时遇到了很多麻烦，希望这会有所帮助。
【讨论】：
我最近在 github 下发现了这个项目： http://github.com/rs/SDURLCache 该方法与我之前在此处描述的答案 How to save the content in UIWebView for faster loading on next launch? 完全相同，但代码看起来更精致，所以尝试一下可能是有意义的。
【讨论】：