How to use local variable observers
Swift version: 5.10
You should already be familiar with the concept of property observers in Swift – those willSet and didSet blocks you can attach to property on classes and structs. Well, those same blocks can be attached to local and global variables as well, allowing you to respond to changes easily.
The syntax is identical: create your variable, give it an initial value, then provide willSet and/or didSet closures inside braces, like this:
var name = "Taylor Swift" {
didSet {
print("Name changed to \(name)!")
}
}
name = "Justin Bieber"That will print “Name changed to Justin Bieber!” when run.
SPONSORED Get accurate app localizations in minutes using AI. Choose your languages & receive translations for 40+ markets!
Sponsor Hacking with Swift and reach the world's largest Swift community!
Available from iOS 8.0
Similar solutions…
- What’s the difference between a static variable and a class variable?
- How to create and use task local values
- What are property observers?
- How to set local alerts using UNNotificationCenter
- What’s the difference between @ObservedObject, @State, and @EnvironmentObject?
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
