Many apps rely on push notifications to inform their users about interesting updates, important events, or interactions on social media that a user probably wants to know about. It's the perfect way to grab your users' attention and inform them about information they are likely interested in. To send push notifications, a lot of companies and developers make use of third-party services like Firebase, Amazon, Pusher, and others. Today, I would like to show you a simple way to send push notifications without needing any of these services. Personally, I like to use this approach in the early stages of...

On iOS, there are several ways to send notifications to users. And typically every method of sending push notifications has a different goal. For example, when you're sending a remote push notification to a user, you will typically do this because something interesting happened outside of the user's device. Somebody might have sent them a message for example, or something exciting happened during a sports game. However, when we schedule notifications on the device locally, we typically do this as a reminder, or in response to a user action. Like, for example, entering or exiting a geofence. In today's post,...

iOS 14 introduced a new way to build apps where you no longer need an App- and SceneDelegate for SwiftUI apps. Learn how to handle deeplinks for these apps in this article. On iOS, it's possible to send users from one app to the next or to send them from a webpage into an app. A link that's used to send a user to an app is typically called a deeplink. Often, there is more than one way for a deeplink to be passed to your app. Because of this, it's not always trivial to handle deeplinks. In today's article,...

One of the features that got screen time at WWDC 2018 but never really took off is the signposting API, also known as os_signpost. Built on top of Apple’s unified logging system, signposts are a fantastic way for you to gain insight into how your code behaves during certain operations. In this post, I will show you how to add signpost logging to your app, and how you can analyze the signpost output using Instruments. Adding signposts to your code If you’re familiar with OSLog and already use it in your app, adding signpost logging should be fairly simple for...

There are many reasons for code to function suboptimally. In a post, I have shown you how to use the Time Profiler to measure the time spent in each method in your code, and how to analyze the results. While a lot of performance-related problems can be discovered, analyzed and fixed using these tools, memory usage must often be debugged slightly differently. Especially if it's related to memory leaks. In today's post, I will show you how to use the Memory Graph tool in Xcode to analyze the objects that are kept in memory for your app, and how to...

Every once in a while we run into performance problems. One thing you can do when this happens is to measure how long certain things in your code take. You can do this using signposts. However, there are times when we need deeper insights in our code. More specifically, sometimes you simply want to know exactly how long each function in your code takes to execute. You can gain these insights using the Time Profiler Instrument. In today's article, I will show you how you can use the Time Profiler to analyze your code, and how you can optimize its...

Whenever we write code, we want our code to be well-designed. We want it to be flexible, elegant and safe. We want to make sure that Swift’s type system and the compiler catch as many of our mistakes as possible. It’s especially interesting how Swift’s type system can help us avoid obvious errors. For example, Swift won’t allow you to assign an Int to a String property like this: var anInt = 10 anInt = "Hello, World!" The Swift compiler would show you an error that explains that you can’t assign a String to an Int and you’d understand this....

Lots of iOS developers eventually run into code that calls upon DispatchQueue.main. It's often clear that this is done to update the UI, but I've seen more than a handful of cases where developers use DispatchQueue.main as an attempt to get their code to work if the UI doesn't update as they expect, or if they run into crashes they don't understand. For that reason, I would like to dedicate this post to the question "When should I use DispatchQueue.main? And Why?". Understanding what the main dispatch queue does In iOS, we use dispatch queues to perform work in parallel....

If you're working on an app that requires access to a user's location, even when your user has sent your app to the background, you might have noticed that when you ask the user for the appropriate permission, iOS 13 shows a different permissions dialog than you might expect. In iOS 12 and below, when you ask for so-called always permissions, the user can choose to allow this, allow location access only in the foreground or they can decide to now allow location access at all. In iOS 13, the user can choose to allow access once, while in use...

If you use Core Data in your apps, you might be aware that the larger and more complicated your set up becomes, the harder it is to debug. It's at this point where you might start to get frustrated with Core Data and its black-box kind of implementation. You might think that you simply have to trust that Core Data will do the ideal thing for your app. Furthermore, you might have a set up with multiple managed object contexts, each confined to its own thread. And when your app crashes sometimes, you think it's related to Core Data in...