Protocol Oriented Programming Advanced Swift Programming raywenderlichcom

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Swift protocols give all nominal types polymorphic behavior. This video compares class versus protocol based designs. • View the full course here: • https://videos.raywenderlich.com/cour... • --- • About www.raywenderlich.com: • raywenderlich.com is a website focused on developing high-quality programming tutorials. Our goal is to take the coolest and most challenging topics and make them easy for everyone to learn – so we can all make amazing apps. • We are also focused on developing a strong community. Our goal is to help each other reach our dreams through friendship and cooperation. As you can see below, a bunch of us have joined forces to make this happen: authors, editors, subject matter experts, app reviewers, and most importantly our amazing readers! • ---- • From: • https://www.raywenderlich.com/148448/... • Imagine you’re developing a racing game. You can drive a car, ride a motorcycle, or even fly a plane. A common approach to creating this type of application is by using object oriented design, encapsulating all of the logic inside of an object that gets inherited to all of those that share similarity. • This design approach works, but does come with some drawbacks. For example, if you add the ability to create machines that also require gas, birds that fly in the background, or anything else that may want to share game logic, there isn’t a good way to separate the functional components of vehicles into something reusable. • This scenario is where protocols really shine. • Swift has always let you specify interface guarantees on existing class, struct and enum types using protocols. This lets you interact with them generically. Swift 2 introduced a way to extend protocols and provide default implementations. Finally, Swift 3 improves operator conformance and uses these improvements for the new numeric protocols in the standard library. • Protocol are extremely powerful and can transform the way you write code. In this tutorial, you’ll explore the ways you can create and use protocols, as well as use protocol-oriented programming patterns to make your code more extensible. • You’ll also see how the Swift team was able to use protocol extensions to improve the Swift standard library itself, and how it impacts the code you write. • Why Not Base Classes? • Protocol extensions and default implementations may seem similar to using a base class or even abstract classes in other languages, but they offer a few key advantages in Swift: • Because types can conform to more than one protocol, they can be decorated with default behaviors from multiple protocols. Unlike multiple inheritance of classes which some programming languages support, protocol extensions do not introduce any additional state. • Protocols can be adopted by classes, structs and enums. Base classes and inheritance are restricted to class types. • In other words, protocol extensions provide the ability to define default behavior for value types and not just classes. • ou’ve seen the power of protocol-oriented programming by creating your own simple protocols and extending them using protocol extensions. With default implementations, you can give existing protocols common and automatic behavior, much like a base class but better since it can apply to structs and enums too. • In addition, protocol extensions can not only be used to extend your own protocols, but can extend and provide default behavior to protocols in the Swift standard library, Cocoa, Cocoa Touch, or any third party library. • To continue learning more about protocols, you should read the official Apple documentation. • You can view an excellent WWDC session on Protocol Oriented Programming on Apple’s developer portal for a more in-depth look into the theory behind it all. • The rationale for operator conformance can be found on the Swift evolution proposal. You might also want to learn more about Swift collection protocols and learn how to build your own. • Finally, as with any new programming paradigm, it is easy to get overly exuberant and use it for all the things. This interesting blog post by Chris Eidhof reminds us that we should beware of silver bullet solutions and using protocols everywhere “just because”.

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