‘mutating’ in Swift
2 min readMar 29, 2019
As we all know, Classes are reference type whereas Structures and Enumerations are of a value type in swift. What does that mean is that a class object shares a single instance of the object and passes the same reference if passed to any function or new object whereas the value type is the one which creates a copy of it and passes only the value.
This post was originally posted at https://agrawalsuneet.github.io/blogs/mutating-in-swift/ and reposted on Medium on 29th Mar 2019.If we try to change any variable inside a class it’s straight forward.
class Employee {
var name : String
var teamName : Stringinit(name: String, teamName: String) {
self.name = name
self.teamName = teamName
}func changeTeam(newTeamName : String){
self.teamName = newTeamName
}
}var emp1 = Employee(name : "Suneet", teamName:"Engineering")print(emp1.teamName) //Engineering
emp1.changeTeam(newTeamName : "Product")
print(emp1.teamName) //Product
Whereas if you try to do the same in any value type, it will show us a compilation error,
struct Employee {
var name : String
var teamName : Stringinit(name: String, teamName: String) {
self.name = name
self.teamName = teamName
}func changeTeam(newTeamName : String){
self.teamName = newTeamName
//cannot assign to property: 'self' is immutable }
}
It will show us the below error
cannot assign to property: 'self' is immutable