When would you use self in a method?

Paul Hudson    @twostraws    November 8th 2021

Updated for Xcode 14.2

Inside a method, Swift lets us refer to the current instance of a struct using self, but broadly speaking you don’t want to unless you specifically need to distinguish what you mean.

By far the most common reason for using self is inside an initializer, where you’re likely to want parameter names that match the property names of your type, like this:

struct Student {
    var name: String
    var bestFriend: String

    init(name: String, bestFriend: String) {
        print("Enrolling \(name) in class…")
        self.name = name
        self.bestFriend = bestFriend
    }
}

You don’t have to use that, of course, but it gets a little clumsy adding some sort of prefix to the parameter names:

struct Student {
    var name: String
    var bestFriend: String

    init(name studentName: String, bestFriend studentBestFriend: String) {
        print("Enrolling \(studentName) in class…")
        name = studentName
        bestFriend = studentBestFriend
    }
}

Outside of initializers, the main reason for using self is because we’re in a closure and Swift requires it so we’re clear we understand what’s happening. This is only needed when accessing self from inside a closure that belongs to a class, and Swift will refuse to build your code unless you add it.

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