Kotlin - Rob Kerr's Blog

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Kotlin

A collection of 9 posts

Filtering Collections in Swift, Kotlin and JavaScript

Extracting members of a collection that match some filtering predicate is a common pattern in programming. Traditionally we would iterate over all members (e.g. with a for or foreach loop), and save each member matching some condition. Most programming languages now provide some single step filter function to eliminate

Awaiting Kotlin suspend functions in serial, parallel and lazy startup modes

Kotlin allows a thread of execution to be suspended until some other asynchronous function completes and returns a result. Suspend functions are most commonly used when a response from an external resource is needed to complete the suspend function.

REPL Tool Reference

It's helpful to experiment with language syntax in a REPL tool before pasting code into your editor. REPL is an acryonym for Read, Evaluate, Print, Loop. REPL tools are simple interactive programming environments primarily used to validate syntax and algorithms. Swift The main Swift REPL tool is the Playground feature

Using Firebase Auth claims with Swift, Kotlin and JavaScript

Firebase Authentication supports built-in and custom user claims that allow us to conditionally expose functionality to users based on authorization groups. This post demonstrates the syntax to add custom claims in a Firebase backend, and read claims from mobile apps. What are Claims? In identity systems, a "Claim" is is

Async/Await Syntax in Swift, Kotlin and JavaScript

Most modern languages support the ability for asynchronous function calls to be called from synchronous code blocks. This language feature is usually called async/await. This post is a brief syntax scratchpad comparing async/await in different languages. Swift In Swift, an await-able async function is created by adding the

Android Jetpack Compose View Model Eventing Architecture

A common Android architectural pattern is to consume events in a UI View that are triggered from asynchronous web service code in a View Model. While there are many approaches to solving this problem, I wanted to share the approach I often use. You may have another approach that works

ForEach Syntax in Swift, Kotlin and JavaScript

ForEach is a common pattern in programming modern programming languages. Prior to ForEach, the standard approach to iterating over an array of objects was to use a for loop stepping from the first index to the last. ForEach syntax has extra utility in languages that support many types of collections:

Checking for Google Play Services with Kotlin

In many countries we can assume Android users use devices that have Google Play Services pre-installed, but not every Android device in the world actually does. It's possible that code written with the assumption that Play Services is available may crash--something we certainly don't want. What we do want is

Jetpack Compose

Adding a dropdown menu to a Jetpack Compose TopAppBar

Adding a dropdown menu to a Jetpack ComposeTopAppBar is quite easy, but simple examples aren't so easy to find! This post has a canonical example to use as a basis for your dropdown menu. Add a Scaffold that Includes a TopAppBar The first step is to create the Compose view