Why is jQuery Ajax not working in Cordova iOS app

Question

I am building a Cordova app that uses jQuery Ajax to upload images to our server. The uploads were working for a while on both Android and iOS, then after a while they suddenly stopped working on iOS. Now, after a few seconds of trying to access a website, the request fails and I get an error message, which isn't much help. The error is like the following:

readyState: 0
status: 0
statusText: "error"

My code is:

    $.ajax("http://testapi.com/api", {
        data: submission,
        processData: false,
        contentType: false,
        method: "POST",
        // submission was successful
        success(data) {
          if (JSON.parse(data).success) {
            // backend validated and accepted submission
          } else {
            // backend rejected submission due to validation errors
          }
        },
        // submission failed
        // eslint-disable-next-line no-unused-vars
        error(xhr, text, error) {
          alert(
            JSON.stringify(xhr) + "  " + text + " " + JSON.stringify(error)
          );
        }
      });

My Content Security Policy, in index.html is:

<meta http-equiv="Content-Security-Policy" content="default-src * blob: gap://* file: http: https: ; style-src 'self' 'unsafe-inline'; script-src * blob: file: 'unsafe-inline' 'unsafe-eval' http: https: ; img-src 'self' data: blob: file: ; media-src * blob: file:  http: https: ;"

And config.xml is: `

    <config-file parent="NSCameraUsageDescription" target="*-Info.plist">
        <string>World Bee Count needs access to your camera and photo library</string>
    </config-file>
    <edit-config file="*-Info.plist" overwrite="true" target="NSLocationWhenInUseUsageDescription">
        <string>need location access to find things nearby</string>
    </edit-config>
    <edit-config file="*-Info.plist" overwrite="true" target="NSLocationAlwaysAndWhenInUseUsageDescription">
        <string>need location access to find things nearby</string>
    </edit-config>
    <string file="*-Info.plist" overwrite="true" target="NSLocationAlwaysUsageDescription">
        <string>need location access to find things nearby</string>
    </string>
    <config-file parent="NSPhotoLibraryUsageDescription" target="*-Info.plist">
        <string>World Bee Count needs access to your camera and photo library</string>
    </config-file>
    <preference name="StatusBarOverlaysWebView" value="false" />
    <preference name="StatusBarBackgroundColor" value="#2D81C1" />
    <preference name="Fullscreen" value="true" />
    <feature name="CDVWKWebViewEngine">
        <param name="ios-package" value="CDVWKWebViewEngine" />
    </feature>
    <preference name="CordovaWebViewEngine" value="CDVWKWebViewEngine" />
    <preference name="WKWebViewOnly" value="true" />
</platform>
<engine name="ios" spec="5.1.0" />
<plugin name="cordova-plugin-geolocation" />
<plugin name="cordova-plugin-device" />
<plugin name="cordova-plugin-file" />
<plugin name="cordova-plugin-filepath" />
<plugin name="cordova-plugin-whitelist" />
<plugin name="cordova-plugin-add-swift-support" />
<plugin name="com.subitolabs.android.cordova.galleryapi" spec="https://github.com/Collaborne/cordova-gallery-api.git"></plugin>
<plugin name="cordova.plugins.diagnostic" />
<plugin name="cordova-plugin-android-permissions" />
<plugin name="cordova-plugin-splashscreen" source="npm" />
<plugin name="cordova-plugin-camera-preview"></plugin>
<plugin name="cordova-plugin-wkwebview-engine" spec="~1.2.1" />
<plugin name="cordova-plugin-screen-orientation" spec="~3.0.2" />`

<access origin="*" />
<allow-intent href="*" />
<allow-navigation href="*" />

I am running this on iOS 13 and using PhoneGap build

My problem is most similar to this Ajax Not working in IOS 9.0 Cordova

I tried updating my config.xml according to this question But it doesn't seem to be working

Any help is would be very much appreciated, I've been working on this for hours and can't seem to get anywhere

Answer 1

OK, I found the problem was because of a recent update from UIWebView to WKWebView, which was breaking the Ajax code. I added the cordova-plugin-wkwebview-file-xhr plugin to my project as described in the documentation. I also removed the version spec on the WKWebView engine plugin. My config.xml was edited to include the following:

<plugin name="cordova-plugin-wkwebview-engine" />
<plugin name="cordova-plugin-wkwebview-file-xhr" spec="~2.1.4" />

And under

<platform name="ios">
....
<preference name="AllowUntrustedCerts" value="on" />
<preference name="InterceptRemoteRequests" value="all" />
<preference name="NativeXHRLogging" value="full" />

I tried various combinations of the preferences, but only this combination worked. However, NativeXHRLogging could be disabled as it didn't seem to matter. After this everything started working once again

Answer 2

I had the same problem when building with Cordova IOS 6.1.1.

I tried above solution but got build errors with -engine as mentioned.

I removed -engine and just used the latest file-xhr and it worked.

Just use the following plugin, worked with or without the above mentioned preferences.

<plugin name="cordova-plugin-wkwebview-file-xhr" source="npm" version="3.0.0" />