Question

I’m loading a remote webpage into an iOS webview which relies on js and css assets. To improve the performance particularly on 3G networks, I’m hoping to call these assets from files local to the iOS device.

The website backing the iOS app is also used by mobile phone browsers, not just the iOS app, so subclassing NSURLRequest to register my own URL prefix (myurl://) is not ideal.

I already have code that launches mobileSafari for URLs outside of my domain:

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
    NSURL *url = [request URL];
    NSString *hostname = [url host];

    if (![hostname hasSuffix:@".mysite.com"] && navigationType == UIWebViewNavigationTypeLinkClicked) {
        [[UIApplication sharedApplication] openURL:url];
        return NO;
    }
    return YES;
}

This method is called from the same controller implementation with code like this:

- (void)viewDidLoad {
    [super viewDidLoad];
    // ...
    webView.delegate = self;

    // ...

        NSURL *url = [[NSURL alloc] initWithString:([path length] > 0 ? path : @"http://mysite.com/mobile/index")];
        NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
        [webView loadRequest:request];

    // ...

}

I’ve reviewed several other questions ( How to use an iPhone webView with an external HTML that references local images? , Dynamically loading javascript files in UIWebView with local cache not working, iOS WebView remote html with local image files, Using local resources in an iPhone webview ) but they all seem to miss a key element to my problem.

The first link has the start of something promising:

if ([url isEqualToString:@"http://path-to-cdn.com/jquery-1.8.2.min.js"]) {
    fileToLoad = [[NSBundle mainBundle] pathForResource:@"jquery-1.8.2.min" ofType:@"js"];
}

If that’s a sensible approach, I’m stuck on how to get from passing that fileToLoad NSBundle into the webView’s loadRequest, since that’s expecting a URL.

Answer 1

I think I’m on the right path after realizing that I could use the output of stringByAppendingPathComponent as a URL, like so…

if (![hostname hasSuffix:@".mysite.com"] && navigationType == UIWebViewNavigationTypeLinkClicked) {

    NSString *urlString = [url absoluteString];
    if ([urlString isEqualToString:@"http://path-to-cdn.com/jquery-1.8.2.min.js"]) {
        NSString *tempurl = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"js/jquery-1.8.2.min.js"];
        [webView loadRequest:[NSMutableURLRequest requestWithURL:tempurl]];
    } else {
        [[UIApplication sharedApplication] openURL:url];
    }
    return NO;
}
return YES;

I don’t have it working yet (it’s still loading the remote URL) but I think I’m on the right path.