Unit Testing Dispatch Queues With Dependency Injection

September 30, 2018 | Swift, Networking, Unit Testing, iOS, macOS, tvOS, watchOS

We write asynchronous code when we know a task will take time to complete, whether because it's computationally expensive or we're making a network request. Testing this code can be difficult, especially when the asynchronous logic is internal. For example, let's say we're making a fire and forget request to load an image into an image view? We would likely make the request on a background queue and . . .

Convenient Sorting With Swift Key Paths

September 30, 2018 | Swift, iOS, macOS, tvOS, watchOS

Key paths were introduced in Swift 4 and allow you to reference a type's properties without evaluating them. In this tutorial, we'll use key paths to write a generic array extension that makes sorting more convenient with code that is easier to read.

Using Switch Statements And Case Let for Type Checking in Swift

September 8, 2018 | Swift, Control Flow, iOS, macOS, tvOS, watchOS

One thing that bothers many developers about using if statements for type checking in Objective-C is that it suggests a specific order of importance. For example, here's how you might use type checking in an Objective-C `prepareForSegue` method. This Swift version is much more concise, but we still have . . .

Downloading, Caching & Decoding Images Asynchronously with Alamofire: Part 2 (Swift 4)

August 11, 2018 | Swift, Alamofire, Networking, iOS, macOS

In Part 1 of this tutorial, I explained how to use the Alamofire and AlamofireImage libraries to asynchronously download and cache images to be displayed in a UICollectionView. At the end of that project, we still had a performance problem. UIImage by default waits until right before display to decode . . .

Downloading, Caching & Decoding Images Asynchronously with Alamofire: Part 1 (Swift 4)