Swift

Writing Core Data code with performance in mind helps to prepare your app for the future. Your database might be small in the beginning but can easily grow, resulting in slow queries and decreased experience for the user. Since I started writing the Collect by WeTransfer app in 2017 I've ...

Expressible literals allow you to initialize types by making use of literals. There are multiple protocols available in the Swift standard library and chances are big that you've already been using one of those. An example is the ExpressibleByStringLiteral allowing us to initialize a String using surrounding double quotes instead ...

Swift 5 introduced a decent version of string interpolation with SE-228 and updated the old version of the ExpressibleByStringInterpolation protocol that has been deprecated since Swift 3. The new version of this protocol allows us to write powerful extensions to existing types that define how objects interact when used within ...

Custom debug descriptions can help you debug your own custom objects, structs, errors, and other types. Whenever you print out an object you might end up with basic information that doesn't really help you solve your issue. Printing out a struct shows you all the values while you might only ...

URLs are everywhere in an app we built. We reference local files using bundle paths, we fetch data from a path pointing to our API, and we fetch images to display visuals. While working with URLs we often need to verify things like making sure that it's pointing to a ...

Custom operators in Swift can make your code easier to read and simpler to maintain. Code can be written less lines of code while keeping it clear what is happening. Custom operators are also known as advanced operators and allow you to combine two instances with a self-chosen infix, prefix, ...

Custom subscripts in Swift allow you to write shortcuts to elements from collections or sequences and can be defined within classes, structures, and enumerations. You can use subscripts to set and retrieve values without exposing the inner details of a certain instance. An instance can define multiple subscripts and a ...

Apple provides us with great classes like the NSFetchedResultsController to interact with Core Data databases in our apps. The API evolved over the years with additions like support for the new NSDiffableDataSource. However, there are still scenarios where the default API is not helping enough. At WeTransfer, we heavily make ...

Testing private methods and variables is often something we run into when writing tests for our applications. You could think that it's needed to fully verify that your code is working as expected and it helps you to get to that 100% code coverage. If you're new to unit testing ...

Mocking data requests that are triggered by either Alamofire or URLSession is something we all run into when we start writing tests for our networking layer. When writing tests, it's important that we don't actually run the requests so we don't mess up our backend database with dummy data. Also, ...

A command-line tool can be very useful for automating common tasks to boost developer productivity. While developing iOS applications we often make use of command-line tools like Fastlane and CocoaPods but it's less common to write your own command-line tools for daily use. The Swift Package Manager makes it a ...

With more than 30k stars on Github, you can tell that Alamofire is a popular framework to use for iOS and Mac projects. It makes network implementations easy to do and it makes certain hard things easier, like retrying a request, authentication layers, or certificate pinning. Alamofire 5 was released ...