Adrian Hall

Adrian Hall

Microsoft Program Manager by day; Mobile Developer by night

Recent posts

Deploy an AWS AppSync GraphQL API with CloudFormation

April 17, 2018  15 minute read  

There are lots of tutorials about creating an AWS AppSync API from the ground up using the console. However, sooner or later, you are going to want to create an API for production. You could, just as simply, point-and-click your way around the console to produce the same API. However, that is fraught with problems. You can’t check that API into source code control, nor can you repeatedly deploy the API. Ultimately, you’ll want to automate your deployments. This article is about how you can ...

Easy EditText content validation with Kotlin

April 11, 2018  3 minute read  

One of the things that I always deal with in my apps is the need to validate the input fields of a form. I can easily do this with this sample fragment of code (for example, for a length check): field.addTextChangeListener(object: TextWatcher { override fun afterTextChanged(s: Editable?) { val content = s?.text.toString() s?.error = if (content.length >= 6) null else "Minimum length = 6" } override fun beforeTextChanged(s: Editable?) { } override fun onTextChanged(s: Edita...

Using dependency injection with Koin

April 06, 2018  6 minute read  

In a recent post, I described how I can do app analytics by using the AWS Mobile SDK and an AWS Mobile Hub project. This is a great way to get usage analytics for your app, but it requires a tight coupling between the provider (the AWS Provider and AnalyticsClient) and the app. You need to initialize the provider early on (preferably in the Application wrapper or the first activity). That causes a tight linkage between the activities where it is used and the client object. This has several i...

Lessons in Kotlin: Toolbar Icons and Reflection

April 01, 2018  5 minute read  

There are many tutorials online on how to produce an Android app bar with an options menu — so much so that it can be boiled down to a few steps, and I’ll reproduce them here: Step 1: Create resources You actually need two resources. The first is a menu: <?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"> <item android:id="@+id/mainActionCamera" an...

Lessons in Kotlin Threading: An Animated Splash Screen

March 29, 2018  2 minute read  

I find quite a lot of Android apps have splash screens. Some splash screens are for showing off the logo; others for hiding the extensive data load times. Whatever the reason, it’s a way for a little bit of creativity to shine through. My first effort My new app needs a splash screen. Splash screens aren’t hard until you need to do something that takes some time, and there are many tutorials on how to produce one out on the Internet. I’m going to focus on the one problem I had. Let’s take a...