Category Archives: iOS

Cordova, Ionic, iOS, Phonegap, SASS

Remove Windows Phone CSS in Ionic 2/3 to save space

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Lets face it, no-one uses Window Phone any more. However, in Ionic 3 there are several skins which are built in to the CSS to emulate the display of the platform that the app is running on. These are ios (iOS, apple devices), md (Material Design – Android devices and Ionic default skin) and wp (window phone). As each of these is different and affects almost all widgets, they are each responsible for roughly 25% of the CSS size of ionic (which can be big – 250kb or so).

So, as no-one uses windows phone and we don’t want to have to test multiple platforms we can easily remove it from the CSS build to save time, space and complexity.

Firstly, copy the SASS config into our custom config directory; we will use this to override the default Ionic SASS config:

mkdir config
cp ./node_modules/@ionic/app-scripts/config/sass.config.js config

Then edit your package.json file and create or add a config dictionary to it like:

    "config": {
        "ionic_sass": "./config/sass.config.js"
    },

Finally, open up config/sass.config.js, find the excludeFiles section and add the following:

  excludeFiles: [
      /\.(wp).(scss)$/i
  ],

If you don’t want to match different platforms with different Ionic themes/skins (which while nice takes quite a bit of time to fully test), you can choose to use eg the Material Design skin only by doing something like:

  excludeFiles: [
      /\.(ios|wp).(scss)$/i
  ],

Apache, Cordova, iOS, Linux, Phonegap, Web Apps

Apache configuration for WkWebView API service (CORS)

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Switching from UIWebView to WKWebView is great, but as it performs stricter CORS checks than standard Cordova/Phonegap it can seem at first that remote API calls are broken in your app.

Basically, before WKWebView does any AJAX request, it first sends a HTTP OPTIONS query and looks at the Access-Control-* headers that are returned to determine if it is able to access the service. Most browsers can be made to allow all AJAX requests via a simple “Access-Control-Allow-Origin: *” header, however WKWebView is more picky. It requires that you expose which methods (GET, POST, etc); and which headers are allowed (eg if you are using JSON AJAX requests you probably need to use a “Content-Type: application/json” header in your main request).

Rather than having to update your API service, you can work around this in a general way using the following Apache config:

    # Required configuration for iOS WkWEBVIEW

    # Allow any location to access this service
    Header always set Access-Control-Allow-Origin "*"

    # Allow the following headers in requests (X-Auth is a custom header, also allow Content-Type to be specified)
    Header always set Access-Control-Allow-Headers "X-Auth, content-type, origin"
    Header always set Access-Control-Expose-Headers "X-Auth"

    # Allow the following methods to be used
    Header always set Access-Control-Allow-Methods "GET, POST, OPTIONS"

    # WkWebView sends OPTIONS requests to get CORS details. Don't tie up the API service with them;
    # just answer them via apache itself
    RewriteEngine On
    RewriteCond %{REQUEST_METHOD} =OPTIONS
    RewriteRule .* - [R=204,END]

Note the last line answers any HTTP OPTIONS request with blank content and returns it straight away. Most API services would cause a lot of CPU processing just to handle a single request whether it is a true request or an OPTIONS query, so we just answer this straight from Apache without bothering to send it through to the API. The R=204 is a trick to specify that we don’t return any content (HTTP 204 code means “Success, but no content”). Otherwise if we used something like R=200 it would return a page talking about internal server error, but with a 200 response which is more bandwidth, more processing and more confusing for any users.

Cordova, Ionic, iOS, Phonegap

Using Ionic’s WKWebView Engine with standard cordova/phonegap projects

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The guys at ionic have created a branch of phonegap’s WKWebView Engine (for iOS) with a number of improvements such as local AJAX request ability. This is great for ionic projects, however I wanted to see if it could be used in a standard phonegap project for which the standard WKWebView plugin wouldn’t work.

For those who don’t know, older versions of iOS had an implementation of webview which was called UIWebView. This had a number of bugs and performance issues, however because cordova/phonegap strive to maintain backwards-compatibility, it is still the default within phonegap projects. WKWebView is faster, more stable and has newer features such as IndexedDB, however it has some additional security restrictions (especially with CORS and local file loading) meaning it is not simply a drop-in replacement for UIWebView.

Installation is simple, more details can be found on the github project page, however basically just run:

cordova plugin add https://github.com/ionic-team/cordova-plugin-wkwebview-engine.git --save

and it will be included in your iOS project. Make sure that your app works (and detects it’s being run from within cordova) when the window.location is set to 'http://localhost:8080/' rather than the usual file:// path. Then, add the necessary configuration into config.xml:

<platform name="ios">
    <access origin="http://localhost:8080/*" />
    <allow-navigation href="http://localhost:8080/*" />
    <feature name="CDVWKWebViewEngine">
        <param name="ios-package" value="CDVWKWebViewEngine" />
    </feature>
    <preference name="CordovaWebViewEngine" value="CDVWKWebViewEngine" />
</platform>

However, even if you do this, when you open the test app you’ll find that you are for some strange reason unable to scroll! This is because the ionic framework doesn’t use body scrolling, it has subelements with overflow: auto set on them. However for most non-ionic apps you probably want body scrolling. Simply change add the following into the ios platform configuration section in config.xml:

    <preference name="ScrollEnabled" value="true" />

If you are accessing remote API services, you’ll also need to modify some CORS settings on your server. In my post tomorrow I’ll show you how to do this easily without increasing the load on your API service.