FREE TRIAL: Accelerate your app development career with Hacking with Swift+! >>

Summary: Functions

Paul Hudson    @twostraws   

We’ve covered a lot about functions in the previous chapters, so let’s recap:

  • Functions let us reuse code easily by carving off chunks of code and giving it a name.
  • All functions start with the word func, followed by the function’s name. The function’s body is contained inside opening and closing braces.
  • We can add parameters to make our functions more flexible – list them out one by one separated by commas: the name of the parameter, then a colon, then the type of the parameter.
  • You can control how those parameter names are used externally, either by using a custom external parameter name or by using an underscore to disable the external name for that parameter.
  • If you think there are certain parameter values you’ll use repeatedly, you can make them have a default value so your function takes less code to write and does the smart thing by default.
  • Functions can return a value if you want, but if you want to return multiple pieces of data from a function you should use a tuple. These hold several named elements, but it’s limited in a way a dictionary is not – you list each element specifically, along with its type.
  • Functions can throw errors: you create an enum defining the errors you want to happen, throw those errors inside the function as needed, then use do, try, and catch to handle them at the call site.
Hacking with Swift is sponsored by Essential Developer

SPONSORED Join a FREE crash course for iOS devs who want to become complete senior developers — from October 18th to 24th. Learn how to apply iOS app architecture patterns through a series of lectures and practical coding sessions.

Learn more

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!

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.