I want to run Pyodide in an iOS offline environment.

[otmb]

I want to run Pyodide in an iOS offline environment.
HTTP Request worked fine online from WKWebView, but I get an error when fetching wasm with an offline local path.
Unhandled Promise Rejection: TypeError: Unexpected response MIME type. Expected 'application/wasm'

After some trial and error, I found that I could call wasm from XMLHttpRequest.
As a compromise, Overwrite fetch with XMLHttpRequest.

async function fetch(filename) {
    const promise = new Promise((resolve, reject) => {
        const xhr = new XMLHttpRequest();
        xhr.open('GET', filename);
        xhr.responseType = 'arraybuffer';
        xhr.addEventListener('load', (e) => resolve(xhr.response));
        xhr.send();
    });

    const response = new Response(await promise.then(), {headers: new Headers([['Content-Type', 'application/wasm']])});

    return response;
}

Is there any other good way?
Thanks.

Here is the code used for the evaluation.
https://gist.github.com/otmb/2eefc9249d347103469741542f135f5c

[rth]

with an offline local path

Normally browsers will not allow loading .wasm files from local paths see FAQ. I see you have

        let config = WKWebViewConfiguration()
        config.preferences.setValue(true, forKey: "allowFileAccessFromFileURLs")

but I'm not sure if that is enough to bypass this restriction.

In your case, I would start with launching a local HTTP server to serve Pyodide assets to make sure that works with WKWebView and Swift. Then once this works, try to get rid of the HTTP server to load files directly from local URLs, but I'm not sure that this would be technically possible.

[otmb]

Thank you for answering.

The specification that the local path cannot be read is helpful.
Even if I set allowFileAccessFromFileURLs, it seems that some files can be fetched and some cannot be read.
As it is said, it seems appropriate to have an HTTP server.
The XMLHttpRequest I've tried isn't mainstream as it can be blocked when the version changes.

[Klaus-Pete]

This one solved the problem for me:
-> add a configuration to the info.plist in the iOS project:
ionic-team/capacitor@7c0d58c