Dynamically loading javascript files in UIWebView with local cache not working

Question

I\'m trying to write an application which uses a lot of java script inside a UIWebView. And some of this java script is loaded dynamically (with jquery) when it is needed.

Answer 1

After some more more work I found the solution to my problem. And answer here with what I found.

The solution is to to create a custom NSURLProtocol implementation and register this in the application as handler for the http protocol. The code looks like this (I've omitted some error handling in the code):

#import "MyHttpURLProtocol.h"

@implementation MyHttpURLProtocol

+ (BOOL)canInitWithRequest:(NSURLRequest *)request {
    return [[[request URL] scheme] isEqualToString:@"http"]; // we handle http requests
}

+ (NSURLRequest *)canonicalRequestForRequest:(NSURLRequest *)request {
    return request;
}

- (void) startLoading {
    id<NSURLProtocolClient> client = [self client];
    NSURLRequest* request = [self request];
    NSString *pathString = [[request URL] absoluteString];

    NSString* fileToLoad = nil;
    if ([pathString isEqualToString:@"http://example.com/index.html"]) {
        fileToLoad = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];
    }
    else if ([pathString hasPrefix:@"http://example.com/code.js"]) {
        fileToLoad = [[NSBundle mainBundle] pathForResource:@"code" ofType:@"js"];
    }
    else if ([pathString isEqualToString:@"http://example.com/jquery-1.6.2.min.js"]) {
        fileToLoad = [[NSBundle mainBundle] pathForResource:@"jquery-1.6.2.min" ofType:@"js"];
    }

    NSData* data = [NSData dataWithContentsOfFile:fileToLoad];

    NSHTTPURLResponse* response = [[NSHTTPURLResponse alloc] initWithURL:[request URL] statusCode:200 HTTPVersion:@"HTTP/1.1" headerFields:[NSDictionary dictionary]];

    [client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
    [client URLProtocol:self didLoadData:data];
    [client URLProtocolDidFinishLoading:self];
}

- (void) stopLoading {}

@end

This code allows now to load the index.html file be accessing the following code:

[_webview loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://example.com/index.html"]]];

And don't forget to register the custom protocol in your app delegate:

[NSURLProtocol registerClass:[TOHttpURLProtocol class]];

[NSURLProtocol registerClass:[MyHttpURLProtocol class]];

It's amazing how simple the solution can be after your found it. Here is the link to the updated example project: http://dl.dropbox.com/u/5426092/LocalCacheJsInjectTest-working.zip

And for completeness sake here is the link to the blog post which helped me in finding the solution: http://www.infinite-loop.dk/blog/2011/09/using-nsurlprotocol-for-injecting-test-data/