NEW: Start my new Ultimate Portfolio App course with a free Hacking with Swift+ trial! >>

Protocols

Protocols are a way of describing what properties and methods something must have. You then tell Swift which types use that protocol – a process known as adopting or conforming to a protocol.

For example, we can write a function that accepts something with an id property, but we don’t care precisely what type of data is used. We’ll start by creating an Identifiable protocol, which will require all conforming types to have an id string that can be read (“get”) or written (“set”):

protocol Identifiable {
    var id: String { get set }
}

We can’t create instances of that protocol - it’s a description of what we want, rather than something we can create and use directly. But we can create a struct that conforms to it:

struct User: Identifiable {
    var id: String
}

Finally, we’ll write a displayID() function that accepts any Identifiable object:

func displayID(thing: Identifiable) {
    print("My ID is \(thing.id)")
}
Hacking with Swift is sponsored by Fernando Olivares

SPONSORED Would you describe yourself as knowledgeable, but struggling when you have to come up with your own code? Fernando Olivares has a new book containing iOS rules you can immediately apply to your coding habits to see dramatic improvements, while also teaching applied programming fundamentals seen in refactored code from published apps.

Try the book!

Sponsor Hacking with Swift and reach the world's largest Swift community!

BUY OUR BOOKS
Buy Pro Swift Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 3.3/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.