How to use Swift struct implicit initializer?

Question

Here is the code I have:

struct Algorithm {
    let category: String = ""
    let title: String = ""
    let fileName: String = ""
}

let a = Algorithm(

The autocomplete shows the only valid initializer:

But I was expecting to use the implicit initializer like

Algorithm(category: "", title: "", fileName: "")

This gives the error:

Argument passed to call that takes no arguments

There are even screenshots on another issue that shows this call being successfully used.

What am I doing wrong?

matt · Accepted Answer · 2016-07-07 15:57:50Z

6

The problem is the let. If you declare your properties with var, you'll get the memberwise initializer:

struct Algorithm {
    var category: String = ""
    var title: String = ""
    var fileName: String = ""
}
let alg = Algorithm(category: "", title: "", fileName: "")

But since you supplied default values for all the properties, you don't get the memberwise initializer for let properties. The rule is that you get the implicit memberwise initializer for stored properties without a default value and for var properties (provided you have no explicit declared initializer).

answered Jul 7, 2016 at 15:57

matt

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Greg · Accepted Answer · 2016-07-07 15:46:12Z

5

You provided the default values for the properties that's why compiler won't add the default initialiser. When you remove the default values you will get what you are expecting:

struct Algorithm {
    let category: String
    let title: String
    let fileName: String
}

answered Jul 7, 2016 at 15:46

Greg

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Comments

user3441734 · Accepted Answer · 2016-07-07 15:57:26Z

1

use

struct Algorithm {
    var category: String = ""
    var title: String = ""
    var fileName: String = ""
}

and autocomplete will show you both possibilities

answered Jul 7, 2016 at 15:57

user3441734

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