Check if array contains a specific enum type

Question

What is the best way to determine if an array of enum types contains a specific enum type, the kicker is the enum cases have associated types

for example, with the following data structure, how would I get the first video

let sections = [OnDemandSectionViewModel]

public struct OnDemandSectionViewModel: AutoEquatable {
    public let sectionStyle: SectionHeaderStyle
    public let sectionItems: [OnDemandItemType]
    public let sectionType: SectionType
}

public enum OnDemandItemType: AutoEquatable {
    case video(VideoViewModel)
    case button(ButtonViewModel)
    case game(GameViewModel)
    case collectionGroup(CollectionGroupViewModel)
    case clip(ClipViewModel)
}

I'm trying to find the first video, currently, I'm doing the following, but was curious if there is a better way

for section in sections {
    for item in section.sectionItems {
        switch item {
        case .video(let video):
            print("This is the first video \(video)")
            return
        default: break
        }
    }

Even you can use contains array property. It is far much better than this. — 200_OK
– 200_OK, Commented Feb 8, 2018 at 13:43

David Pasztor · Accepted Answer · 2018-02-08 14:15:26Z

11

You can use Sequence.first(where:), which is pretty much like contains(where:), but instead of simply returning a bool, it returns the first element satisfying the condition in the closure or nil if there's no such element.

let firstVideo = sections.sectionItems.first(where: { item in
    if case .video = item {
        return true
    }
    return false
})

answered Feb 8, 2018 at 14:15

David Pasztor

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1 Comment

user3151675 Over a year ago

This has the advantage of working nice with associated values.

Adamsor · Accepted Answer · 2018-02-08 13:52:39Z

7

If you don't need VideoViewModel contained in enum it's enough to type

if section.sectionItems.contains(where: { item in 
    if case .video = item {
        return true
    }

    return false
}) {
    // Your section contains video
}

answered Feb 8, 2018 at 13:52

Adamsor

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Comments

4b0 · Accepted Answer · 2019-07-25 14:58:09Z

1

Using filter function example:

return section.filter({ $0.sectionType == .video }).first != nil

Or

return section.filter( { $0.sectionType == .video }).count ?? 0 > 0

edited Jul 25, 2019 at 14:58

4b0

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answered Jul 25, 2019 at 14:50

patilh

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