Category: Mobile

Injecting Custom Files into Ionic Build

This post is about including custom .html, .css and .js files in an Ionic 3.x+ project so that they get copied from /src to /www during the build process. Basically, we are talking about files that are handled separately from the webpack compiler process, but you want them to be swept into the test or production build when they get updated.

Step 1: Modify your projects main package.json file in the root directory to override the copying process in ionic:build and ionic:serve. In this example we are referencing a custom library called ionic-config-override.js that controls what we want to copy, and this library lives in the root directory, as well.

{
     . . .
     “scripts”: {
          . . .
          "ionic:build": "ionic-app-scripts build --copy ionic-config-override.js",
          “ionic:serve”: "ionic-app-scripts serve --copy ionic-config-override.js"
     }
     . . .
}

Step 2: Create a JavaScript file of the same name you referenced in package.json for example ionic-config-override.js. In this new JavaScript library use the node.js fs-extra file utility to copy the files you want when the build process is run. Here’s one example:

var fs = require(‘fs-extra’);
fs.copy(‘src/special.html’,’www/special.html’);

Step 3: To test locally instead of using ionic serve, run this new script using the command line command npm run ionic:serve. Or, if you are ready to test on a device run the script using npm run ionic:build android and then when that is completed successfully use ionic cordova run android.

References:
Ionic –copy command

The Copy command source code can be found in your project path @ionic/app-scripts/config/copy.config.js

Additional information can be found on the Ionic forums.

Do I need Ionic’s Geolocation Plugin?

Most likely not. As described in the Cordova documentation and Ionic documentation, the plugin is for devices that don’t already provide an implementation. The vast majority of modern smartphones natively support the WebView Geolocation API. Also, cellphone enabled tablets typically have a GPS. However, WiFi only tablets may be limited to using non-GPS, WiFi-based geolocation, but the Geolocation API will still work although it will be less accurate.

Skipping the plugin simplifies installation and implementation. You don’t have to install it and that eliminates any possible conflicts and provides a minor reduction in application size. You also don’t have to import the plugin into your application components and that simplifies your code. You can simply use navigator.geolocation like you would in any regular JavaScript app:


watchId = navigator.geolocation.watchPosition(success[, error[, options]])

Sample application: https://github.com/andygup/ionic2-esri-map

Using High Accuracy GPS with Mobile Apps

There are times when the built-in GPS simply isn’t good enough for your Android or iOS app. Built-in GPS is good for finding a general location of a geographic feature such as a pond, field, or parking lot. If you need to locate a specific parking space, or a geographic feature within a field, or an inlet to a pond then you’ll need much greater precision of a commercial GPS unit.

Examples. Here is a more specific example to illustrate the concept. Let’s say the application users are mapping insect infected trees in a densely forested urban park. If you are using a smartphone GPS, with an average accuracy of 30+ meters when standing under the tree cover, the latitude/longitude coordinates may end up being unusable for future follow-up because there are dozens of trees within a 30+ meter radius. If you are using a commercial GPS with sub-meter accuracy you can have a much higher degree of certainty that someone will be able to locate that exact tree again.

I’ve seen entire days’ worth of data collection get thrown out the window because of significant location inaccuracies caused by using smartphones and dedicated hand-held consumer GPS units that are well known to outdoor recreational folks. I’ve accidentally sent a backcountry trail maintenance crew to a totally wrong location (they got really mad). All I had was a smartphone GPS and my location coordinate was over a thousand meters off even though the Android Location API returned an “accuracy” value of less than 50 meters. Oops — that’s the difference between precision and accuracy.

Good news. The good excellent news is there are small, handheld commercial GPS units that you can tether to your smartphone via Bluetooth such as the Trimble R1. Units like the R1 are able to override the onboard GPS and when configured correctly work just fine with the browser’s JavaScript-based Geolocation API or native iOS/Android geolocation.

The only downside can be cost. Some of these commercial units cost several thousand dollars and that may be outside the budget of many organizations.

Surprise, Surprise. I spend a ton of time talking to customers about this topic. Many people are very surprised because they regularly use GPS fitness tracker apps or Google Maps and the location information almost always seems very close to reality. The hidden trick is these apps use proprietary software algorithms that attempt to slightly improve accuracy, minimize location fluctuations or even intelligently snap your location to geographic features such as roadways, buildings or trails.

When you are building a custom mobile application, you will be forced to deal with raw, unfiltered geolocation data. And the coordinate data is coming from consumer-grade GPS units mass produced at the lowest possible cost. The antennas are tiny and usually on the back of the device rather than pointed towards the sky. The chipsets are designed to minimize battery usage, because GPS can be extremely battery intensive and generates a lot of heat. They have minimal ability to resolve communication difficulties between your device and GPS satellites, and GPS signals are already relatively weak.

Decisions, decisions. If your budget can’t handle several thousand dollars for a commercial GPS and you only have short term needs you can always look into renting a bluetooth unit. Just make sure to ask if it overrides the onboard GPS chip. You can find GPS rental companies online. There are also consumer-grade Bluetooth GPS units that only cost several hundred dollars. The consumer Bluetooth units aren’t nearly as accurate as commercial units; however, they offer a significant improvement over built-in GPS.