How to automatically create an initializer for a Swift class?

Question

UPDATE: Use structs and not classes. Struct is better in many ways has got an initializer of its own.

This is my model class. Is it possible to create the init method automatically? Everytime I have to initialize all the variables one by one and it costs a lot of time.

class Profile {

    var id: String
    var name: String
    var image: String

    init(id: String, name: String, image: String) {
        self.id = id
        self.name = name
        self.image = image
    }
}

I want self.id = id and other variables to initialize automatically.

Solution 1

Update As of Xcode 11.4

You can refactor (right-click mouse menu) to generate the memberwise initializer for class and struct.

Note that struct automatic initializers are internal. You may want to generate memberwise initializer when defining a module to make it public.

Right-click > Refactor > 'Generate Memberwise Initializer'

For older Xcode

There are handy plugins:

https://github.com/rjoudrey/swift-init-generator https://github.com/Bouke/SwiftInitializerGenerator

Solution 2

Given the following class (or for structs if temporarily change the keyword struct to class and after refactor set back to struct):

class MyClass {
    let myIntProperty: Int
    let myStringProperty: String
    let myOptionalStringProperty: String?
    let myForcedUnwrappedOptionalStringProperty: String!
}

Go to Xcode and:

1. Double click the class name
2. Right click
3. Refactor
4. Generate Member-wise Initializer

Above steps look like this:

Just a tiny second later, Xcode generates this initializer:

internal init(myIntProperty: Int, myStringProperty: String, myOptionalStringProperty: String?, myForcedUnwrappedOptionalStringProperty: String?) {
    self.myIntProperty = myIntProperty
    self.myStringProperty = myStringProperty
    self.myOptionalStringProperty = myOptionalStringProperty
    self.myForcedUnwrappedOptionalStringProperty = myForcedUnwrappedOptionalStringProperty
}

Solution 3

No, there is no such feature for classes. But, if you design this as a struct, you get an memberwise initializer for free — assuming you don't define others initializers yourself.

For instance:

struct Point {
    var x: Float
    var y: Float
}
...
var p = Point(x: 1, y: 2)

From The Swift Programming Language book:

Structure types automatically receive a memberwise initializer if they do not define any of their own custom initializers. Unlike a default initializer, the structure receives a memberwise initializer even if it has stored properties that do not have default values.

The memberwise initializer is a shorthand way to initialize the member properties of new structure instances. Initial values for the properties of the new instance can be passed to the memberwise initializer by name.

Comments

[David P]

Kinda bizarre this doesn't exist...

[Bhavuk Jain]

@Chicken You should use structs. They have so many benefits as compared to classes.

[David P]

I also need Objective-C compatibility.

[Tomte]

Now that some time went by, I'm facing another issue with this when using structs: If you have some default values assigned the internal initializer works well on Swift 5+. But on Swift 4 and below you have to add an initializer manually. So the accepted answer is gold. just quickly change from class to struct, do the refactor thingy, change it back to struct and no hassle. Note: Just for downwards compatibility necessary.

[Paulo Mattos]

@BhavukJain If my answer solved your question, pls be sure to mark it as the accepted answer when you get a chance... thanks man!

[Bhavuk Jain]

I'll upvote it because you mentioned something I didn't know. But still, I'm looking for an answer by how classes can achieve this. Maybe someone has created a tool for it so it can be used directly. There must be a way!

[Paulo Mattos]

@BhavukJain The answer, circa Swift 3.1, is simply no, there isn't such feature for classes :( And peeking into the future it seems no such capability is in the roadmap either (this one was close but it was postponed). Of course, you could always use a code generator for this but it seems too much trouble if you ask me ;)

[Christian Wolf Alves Hess]

swiftinitializergenerator worked perfectly for me, thank you

[Rudedog]

This works well, but note that it only works for class declarations, not struct declarations.

[Daniel Wood]

Unfortunately this doesn't work if you want to make the struct accessible from another module as the memberwise initialisers are set to internal access and require you to recreate the memberwise initialiser by hand (or the tools listed above).

[tyoc213]

Well, indeed doesnt work for structs, but you can change for a moment struct to class, generate the intializer and make it again a struct ;).

[Moris Kramer]

@TangMonk 13.3.1 is an operating system. You mean Xcode 11.3, Yes only in 11.4 for structs and classes. Below that only for aclass. You can use plugins or rename struct to class temporly.

[TangMonk]

I an using Version 11.3.1 (11C504) for Xcode, the 11.4 seems in beta

[Justin]

What a cool feature. It is really handy for adding initializers for view models. It helps to get rid of this boring task. Thanks for your hint.

[Zorayr]

Do you know what could make the refactor options be blurred out? I right click on the class > Refactor > all options are blurred out 😢 my code compiles, I am on Xcode 11.4.

[Burgler-dev]

This one saves me a lot off time, didn't know you had to click on the class/struct name first.

[Aetherna]

Doesn't work for me sadly. My xCode does "boop" sound and nothing happens..