Initialize and fill array with custom object inline

Question

I have an array with 10 objects all of the same self-created class.

let myArray = [CustomObject(), CustomObject(), CustomObject(), CustomObject(), CustomObject(), CustomObject(), CustomObject(), CustomObject(), CustomObject(), CustomObject()]

I wonder if there is a shortcut for creating such an array like in Python where I would do something like

myArray = [CustomObject() for _ in range(10)]

I have seen these solutions: StackOverflow-Link but they don't seem to work with not built-in classes.

let myArray2 = (0...9).map{CustomObject()}

says "Type of expression is amiguous without more context"

Raja Kishan · Accepted Answer · 2020-12-16 17:50:14Z

3

Try this

let myArray = [CustomObject](repeating: CustomObject(), count: 10)

By using Array.init(repeating:) will invoke the CustomObject initialize only one time, and then insert that object into the array multiple times.

If you want to use Array.init(repeating:) with the different object I found one thread and extension https://forums.swift.org/t/support-repeating-initializers-with-closures-not-just-values/14666/5

If you want to use the map and for different object.

let myArray2 = (0...9).map { (_) -> CustomObject in
    CustomObject()
}

edited Dec 16, 2020 at 17:50

answered Dec 16, 2020 at 16:59

Raja Kishan

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4 Comments

Duncan C Over a year ago

Your solution using Array.init(repeating:) will invoke the CustomObject initializer only once, and then insert that object into the array multiple times. That is likely not what the OP wants or expects.

L3n95 Over a year ago

No I need 10 different objects. So the map solution would be what I need?

Raja Kishan Over a year ago

@DuncanC yes you are right. Using Array.init(repeating:) object initializer only one time. so a map is a good solution in my view.

Raja Kishan Over a year ago

If you want to use Array.init(repeating:) with the different object I found one thread and extension forums.swift.org/t/…

user652038 · Accepted Answer · 2020-12-16 18:58:20Z

0

Prefixing an AnyIterator that produces infinite Voids is my recommendation. Then you don’t need to disregard a closure parameter, allowing you to use the initializer directly as a named closure.

AnyIterator { } .prefix(10).map(CustomObject.init)

answered Dec 16, 2020 at 18:58

user652038

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