Better way of iterating through array of custom struct

Question

This is my custom data struct:

struct Absence {
    var type: String
    var date: TimeInterval
}

I have an array of this data struct like this:

var absences: [Absence]

I would like a function to return all the types of an absence. I have written this:

func types() -> [String] {
    var types = [String]()
    for absence in self.absences {
        if !types.contains(absence.type) {
            types.append(absence.type)
        }
    }
    return types
}

I was wondering if there was a better way of iterating through using either map, compactMap or flatMap. I am new to mapping arrays. Any help much appreciated.

Start with `absences.map { $0.type }`. Use a `Set` to get rid of duplicates. — Martin R, Sep 04 '20 at 19:36

score 1 · Accepted Answer · answered Sep 04 '20 at 19:44

1

You could just do the following:

var types = absences.map { $0.type }

If you would like to filter the types:

var types = absences.map { $0.type }.filter { $0.contains("-") }

Or if you simply want to remove all duplicates:

var types = Array(Set(absences.map { $0.type }))

answered Sep 04 '20 at 19:44

finebel

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2

Swift 5.2 or later you can use KeyPath `map(\.type)` – Leo Dabus Sep 04 '20 at 19:56
2

@LeoDabus Was actually writing the same :) – pawello2222 Sep 04 '20 at 19:56
1

Note that using a set like this you will discard the array original order. If you would like to preserve the original order of the elements check this post https://stackoverflow.com/a/34712330/2303865 – Leo Dabus Sep 04 '20 at 19:59
Thank you everyone for your solutions - much appreciated! – Tahmid Azam Sep 05 '20 at 06:39

Better way of iterating through array of custom struct

1 Answers1