You've done all the work to build your app, your UI looks amazing, animations are smooth and you're ready to put your app in the hands of other people. Maybe you're even ready to start offering your app on the App Store! This is a huge achievement if you are currently at this stage in your development cycle, I would like to congratulate you. Being ready to ship your app is a huge accomplishment, especially if it's your first App. I still remember the excitement when I submitted my first app to the App Review team in App Store Connect...

For years I have had a bit of a love and hate relationship with Storyboards. I love how easy they make it for me to set up my AutoLayout constraints, but they can quickly grow unwieldy and for large projects with multiple developers Storyboards are hard to use because of merge conflicts that occur when multiple developers update the UI. For personal projects, however, my Storyboards tend to be small enough to manage. And since I'm the only developer working on them I never have merge conflicts. Yet still, I've never been completely happy with them. The main reason for...

Ever since iOS 6, developers have been able to use collection views and to build interesting custom layouts by subclassing the UICollectionViewLayout or UICollectionViewFlowLayout classes. I even wrote an article about building custom collection view layouts a while ago. Today, I would like to introduce you to a new way of defining collection view layouts called compositional layouts. We're going to build the two layouts shown in the following image: I will first show you how to build a simple grid layout, and from there we'll continue working our way towards the end result. Building a grid layout A very...

At WWDC 2019 Apple announced a couple of really cool features for table views and collection views. One of these cool features comes in the form of UITableViewDiffableDataSource and its counterpart UICollectionViewDiffableDataSource. These new diffable data source classes allow us to define data sources for collection- and table views in terms of snapshots that represent the current state of the underlying models. The diffable data source will then compare the new snapshot to the old snapshot and it will automatically apply any insertions, deletions, and reordering of its contents. In today's article, I will show you how to use UITableViewDiffableDataSource...

One of the topics that I could write dozens of posts on is networking. Making calls to a remote API to retrieve or persist data is something that is a key feature in many apps that are currently in the App Store. Some apps make extensive use of the network while others only need the network to retrieve data periodically. No matter how extensively your app uses the network, the patterns for using the network in a clean and appropriate manner are often (roughly) the same. I have written several posts on networking in the past: Architecting a robust networking...

Both networking and protocols are topics that I could write dozens of posts on, and I would still have more ideas and examples left in my head. In today's article, I would like to combine the topics of networking and protocols and explain how you can design a robust networking layer for your app, that's 100% testable and mockable because everything down to the URLRequest is abstracted behind a protocol. Defining our goals Any time you're getting ready to write code, you should define your goals first. What are you writing? What problems are you trying to solve? This is...

As a developer that uses Xcode on a daily basis for multiple projects, you sometimes need to use different versions of Xcode depending on the project you’re working on. Or maybe you want to try out the latest Xcode beta, for example right after Apple announced it after WWDC. One way to manage is to go to the Apple developer portal, searching for the version you need and download it. You download the .xip file, expand it (eventually, it takes a while) and then you can finally open Xcode. But then you realize you also have to rename it before...

When you're designing a new component for your codebase, you will usually only think of the component itself, and the objects that it interacts with directly. If you're designing a component that authenticates a user, you will typically only consider objects directly related to the authentication flow. You'll take into account that there's probably a network call, and maybe a central current user storage object. You don't want to spend time thinking about objects that are related to that network object since that's not something the component you're designing should care about. For example, if the network object caches responses...

When you're building apps, there are times when you need to perform certain tasks before executing the next task. Imagine a scenario where you need to make a couple of API calls to a webserver to retrieve information before you can begin processing the information that's fetched by all preceding API calls, so it can be used in your app. Usually, you want to perform this work as efficiently as possible. In the example I just outlined, this might mean that you want to fire off your API calls to retrieve information all at once, and begin processing immediately when...

As apps grow larger and larger, their complexity tends to increase too. And quite often, the problems you're solving become more specific and niche over time as well. If you're working on an app like this, it's likely that at some point, you will notice that there are parts of your app that you know on the back of your hand, and other parts you may have never seen before. Moreover, these parts might end up somehow talking to each other even though that seems to make no sense. As teams and apps grow, boundaries in a codebase begin to...