Abstract Classes

Swift Patterns

The title of this episode is a bit misleading because the Swift programming language has no support for abstract classes. There are a few workarounds, though. In this episode, we take a look at two alternatives to the abstract class pattern in Swift.

in Patterns

Namespaces

Swift Patterns

Types need to have a unique name. In Objective-C, naming collisions with other libraries and frameworks are avoided by adding a prefix to a type. That is why we use UIView instead of View and CGRect instead of Rect.

in Patterns

Five Xcode Tips To Speed Up Your Development

Xcode is a pretty complex piece of software and it changes with every major release. Apple's IDE (Integrated Development Environment) has dozens and dozens of tiny secrets, which you only discover the more you use it. In this episode, I share five tips that I use every day and could not do without.

in Tips and Tricks

Combine and Diffable Data Sources

Building Reactive Applications With Combine

In 2019, Apple introduced another powerful API alongside the Combine framework, diffable data sources. Diffable data sources make it almost trivial to build performant table and collection views. In this episode, I show you why diffable data sources work well with the Combine framework. I won't cover diffable data sources in detail in this series, but the API is straightforward and easy to pick up.

in Programming

Reactifying the Week View Controller

Building Reactive Applications With Combine

In this and the next episode, we shift focus to the week view controller. Populating the week view requires a different approach. It contains a table view and the week view model manages an array of WeahterDayData objects. Even though the approach is different, the patterns we apply are similar.

in Programming

Combining Publishers with Zip and Combine Latest

Building Reactive Applications With Combine

The Combine framework defines a range of operators to combine publishers. Combining publishers is a common pattern in reactive programming. In this episode, we improve the efficiency of the RootViewModel class by combining multiple publishers using the zip and combineLatest operators.

in Programming

Reducing State with Subjects

Building Reactive Applications With Combine

We ran into several issues in the previous episode. The assign(to:on) and sink(receiveValue:) methods are convenient, but they don't always cut it. We need a solution that is robust and scales with the complexity of the project.

in Programming

Reducing Complexity and Code Duplication

Building Reactive Applications With Combine

In this episode, we optimize the implementation of the day view controller and the day view model. There are a few details we need to take care of. First, the day view controller should display an error message when its view model emits an error. Second, the day view controller should only display its activity indicator view if it has no weather data to display. Let's tackle these problems one by one.

in Programming

Bridging Imperative and Reactive Programming

Building Reactive Applications With Combine

There are a few user interface issues we need to address in this episode. The day view controller no longer shows its activity indicator view while it is waiting for weather data and the user interface elements that show the weather data should only be shown when there is weather data to display. Let's find out how we can resolve these issues.

in Programming

Driving the User Interface with Publishers

Building Reactive Applications With Combine

In the previous episode, we put the foundation in place to reactify the DayViewController class. In this episode, you learn how to use publishers to drive the user interface of an application.

in Programming

Hiding Implementation Details with Type Erasure

Building Reactive Applications With Combine

The root view controller displays the weather data the publisher emits. Every time the publisher emits weather data, the child view controllers of the root view controller receive the weather data and display it to the user. This works fine, but we can make it more reactive.

in Programming

Using Publishers to Push Data

Building Reactive Applications With Combine

We made good progress in the previous episodes, but we need to make some changes to the RootViewController and RootViewModel classes. We address three issues in this episode. First, the RootViewController class shouldn't be aware of CLLocation objects. Second, the RootViewModel class should expose a publisher that emits weather data. Third, we need to restore the pull-to-refresh feature. Let's get started.

in Programming