Caching Images in Memory

Image Caching in Swift

We added the ability to cancel image requests in the previous episode. This and the next episode focus on caching images. We start simple by caching images in memory.

in Networking

Cancelling Image Requests

Image Caching in Swift

Most applications display images in some way, shape, or form. Those images are often fetched from a remote server, introducing a number of interesting challenges. Performing a request to a remote server takes time and it requires resources. It is therefore important to consider solutions to minimize the number of requests an application makes.

in Networking

Failable Initializers

Swift Patterns

If you are new to Swift, then you may be wondering what a failable initializer is and why you would ever use one. In this episode, I show you how to create a failable initializer and I hope I can convince you of their benefits. I use failable initializers in every project I work on and you may be surprised when I say that you do too.

in Patterns

Recovering from Errors

Building Reactive Applications With Combine

Cloudy shows the user an error if it isn't able to fetch weather data from the weather API. We map any errors that are thrown to WeatherDataError in the RootViewModel class. This solution works fine and it is a fitting implementation for the weather application we are building. In this episode, I show you three other options to handle errors.

in Programming

Handling Errors

Building Reactive Applications With Combine

Even though we successfully used the Combine framework to fetch data from the weather API, the implementation is incomplete. We ignored error handling up until now and it is time to take a closer look at errors and how to handle them.

in Programming

Networking and Schedulers

Building Reactive Applications With Combine

Earlier in this series, you learned that reactive programming can be defined as working with asynchronous streams of data. A network request is an asynchronous operation and that makes reactive programming an excellent match for networking.

in Programming

Adding Type Safety to User Defaults with Extensions

The interface of the UserDefaults class is easy to use, but it lacks type safety. If you want to store and retrieve an enum, for example, you need to jump through a few hoops. Let me show you an example from Cloudy, the application we build in Mastering MVVM With Swift.

in Foundation

Builders

Swift Patterns

The builder pattern isn't a common pattern in Swift and Cocoa development and you don't find it in any of Apple's frameworks. It is one of the Gang of Four design patterns and widely used in Java development.

in Patterns

Subscribing to Settings Changes

Building Reactive Applications With Combine

In this episode, we fix the settings view using the Combine framework. We no longer rely on the delegation pattern to propagate settings changes. In the previous episode, we created a view model for the settings view controller. The settings view model exposes a publisher for each setting. Objects interested in settings changes can subscribe to these publishers. Let me show you how that works.

in Programming

Driving Table View Cells with Combine

Building Reactive Applications With Combine

Earlier in this series, we broke the settings view. The root view controller acts as the delegate of the settings view controller, but nothing happens when the user updates a setting in the settings view. In this and the next episode, we fix what we broke and reactify the application's settings view.

in Programming

Initializer Injection with View Controllers, Storyboards, and Segues

Initializer Injection with View Controllers

In the previous episode, you learned that it is possible to use initializer injection in combination with storyboards as of iOS 13 and tvOS 13. We didn't cover segues in that episode, though. That is the focus of this episode. Let's take a look at an example.

in Storyboards

Initializer Injection with View Controllers and Storyboards

Initializer Injection with View Controllers

Storyboards have many benefits, but they also have a number of significant downsides. Not being able to control the initialization of a view controller is one of them, especially if you want to use initializer injection. As of iOS 13 and tvOS 13, that is no longer a problem. In this episode, I show you how to use initializer injection in combination with storyboards.

in Storyboards