How to filter array of items by another array of items in swift

Question

I have a model named Item and Tag. Item has multi tags. I need to filter array of items by another array of tags. Tags to be used for filter are given by array of string.

I googled but couldn't find answer to solve my situation.

struct Tag {
    let id: Int
    let name: String
}

struct Item {
    let id: Int
    let tags: [Tag]
}

func filter(items: [Item], contains tags: [String]) -> [Item] {
    // Need to implement filter
}

goat_herd · Accepted Answer · 2021-03-29 01:58:51Z

3

Chose 1 in 2 option of return:

     func filter(items: [Item], contains tags: [String]) -> [Item] {
        items.filter { (item) -> Bool in
            let tagNames = item.tags.map({ $0.name })
            return tags.allSatisfy(tagNames.contains)
            return Set(tags).isSubset(of: Set(tagNames))
        }
    }

answered Mar 29, 2021 at 1:58

goat_herd

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6 Comments

Alexander Over a year ago

The map is wasteful. You can just do: tags.allSatisfy { tag in item.tags.contains(tag) }

goat_herd Over a year ago

@Alexander the tags is [String], but item.tags is [Tag]

Alexander Over a year ago

so then: tags.allSatisfy { tag in item.tags.contains(where: { $0.name == tag.name } }

goat_herd Over a year ago

@Alexander Thank you, but it should be: tags.allSatisfy { tag in item.tags.contains(where: { $0.name == tag })}. And if writing like this i think the onwner of this question will hard to understand

Alexander Over a year ago

Yeah, I would extract that predicate into a named function like hasTag, so it could read like tags.allSatisfy(item.hasTag)

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