Set a subset of an array to the same value in swift

Question

Swift 5, iOS 13

I got this code... which is awful.

var horizonalOpacity = [Bool](repeating: false, count: 24)

self.horizonalOpacity[0] = true
self.horizonalOpacity[1] = true
self.horizonalOpacity[2] = true
self.horizonalOpacity[3] = true
self.horizonalOpacity[4] = true
self.horizonalOpacity[5] = true
self.horizonalOpacity[6] = true
self.horizonalOpacity[7] = true
self.horizonalOpacity[8] = true
self.horizonalOpacity[9] = true
self.horizonalOpacity[10] = true
self.horizonalOpacity[11] = true

I can replace with this code, which is ok.

for loop in 0...11 {
   self.horizonalOpacity[loop] = true
}

But can I do better? Can I use map perhaps? or an array slice perhaps?

I have deleted my answer because an identical solution has been given before: https://stackoverflow.com/a/61889091/1187415 — Martin R, Jun 12 '20 at 18:15

score 1 · Answer 1 · answered Jun 12 '20 at 18:08

1

What about

var horizonalOpacity = [Bool](repeating: true, count: 12) + 
                       [Bool](repeating: false, count: 12)

answered Jun 12 '20 at 18:08

Asperi

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This is good, but the answer using replacingSubrange was better, but it disappeared :( before I could vote it up? – user3069232 Jun 12 '20 at 18:15
https://stackoverflow.com/a/48369550/2303865 – Leo Dabus Jun 12 '20 at 18:16

score 1 · Answer 2 · answered Jun 12 '20 at 18:11

1

You can also try to use mapInPlace extension proposed here:

extension MutableCollection {
    mutating func mapInPlace(_ x: (inout Element) -> ()) {
        for i in indices {
            x(&self[i])
        }
    }
}

Then you'd just write:

horizonalOpacity.mapInPlace { $0 = true }

answered Jun 12 '20 at 18:11

pawello2222

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https://stackoverflow.com/a/48369550/2303865 – Leo Dabus Jun 12 '20 at 18:15

Set a subset of an array to the same value in swift

2 Answers2