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Inout Parameters in Swift

with 5 Practical Swift Implementations!

Last Updated: August 29, 2024

Okay, let’s be honest,inout parameters in iOS aren't exactly the talk of the town in most production environments, and you won't find them everywhere.

So, why should you stick around? Great question! You're in the right place if you're all about squeezing out extra performance from your apps.

Before we get rolling, make sure you’re on top of these basics:

• Basic Knowledge of Swift Functions: Know how to define functions and how parameters work.
• Pass by Reference vs. Pass by Value: It’s super important to get this difference for inout to make sense.

Now that we’ve covered the groundwork. Let’s dive in and explore this together!

What is inout Parameter?

In Swift, an inout parameter allows you to pass a variable to a function so that the function can modify the variable’s value, and those changes persist after the function call has returned.

Usually, function parameters are constants in Swift, so if you try to modify them, you’ll get a compile-time error. With keyword inout, you can bypass this restriction.

When to Use inout Parameter?