Updated for Xcode 14.2
It’s possible to modify the properties of a struct, but only if that struct is created as a variable. Of course, inside your struct there’s no way of telling whether you’ll be working with a variable struct or a constant struct, so Swift has a simple solution: any time a struct’s method tries to change any properties, you must mark it as mutating
.
You don’t need to do anything else other than mark the method as mutating
, but doing that gives Swift enough information to stop that method from being used with constant struct instances.
There are two important details you’ll find useful:
mutating
will stop the method from being called on constant structs, even if the method itself doesn’t actually change any properties. If you say it changes stuff, Swift believes you!SPONSORED From March 20th to 26th, you can join a FREE crash course for mid/senior iOS devs who want to achieve an expert level of technical and practical skills – it’s the fast track to being a complete senior developer!
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