Create NSIndexSet from integer array in Swift

Question

I converted an NSIndexSet to an [Int] array using the answer at https://mcmap.net/q/297273/-how-to-get-indexes-from-nsindexset-into-an-nsarray-in-cocoa I need to do essentially the opposite, turning the same kind of array back into an NSIndexSet.

Halfassed

Answer 1

Swift 3

IndexSet can be created directly from an array literal using init(arrayLiteral:), like so:

let indices: IndexSet = [1, 2, 3]

Original answer (Swift 2.2)

Similar to pbasdf's answer, but uses forEach(_:)

let array = [1,2,3,4,5,7,8,10]

let indexSet = NSMutableIndexSet()
array.forEach(indexSet.add) //Swift 3
//Swift 2.2: array.forEach{indexSet.addIndex($0)}

print(indexSet)

Cesta

Thanks, but if I use to reloadTableSection is it work to one section? – Disforest

@BrunoFernandes Uh... What? – Cesta

Answer 2

This will be a lot easier in Swift 3:

let array = [1,2,3,4,5,7,8,10]
let indexSet = IndexSet(array)

Wow!

Unnecessary

Even better, it can be assigned from an Integer Literal. See my answer – Cesta

@AlexanderMomchliov Excellent, that is even better. – Unnecessary

It is very annoying this can't be seen by typing IndexSet.init and using an autocomplete option. – Intelligence

Answer 3

Swift 3+

let fromRange = IndexSet(0...10)
let fromArray = IndexSet([1, 2, 3, 5, 8])

Added this answer because the fromRange option wasn't mentioned yet.

Difficulty

Answer 4

Swift 4.2

From existing array:

let arr = [1, 3, 8]
let indexSet = IndexSet(arr)

From array literal:

let indexSet: IndexSet = [1, 3, 8]

Isocracy

Answer 5

You can use a NSMutableIndexSet and its addIndex method:

let array : [Int] = [1,2,3,4,5,7,8,10]
print(array)
let indexSet = NSMutableIndexSet()
for index in array {
    indexSet.addIndex(index)
}
print(indexSet)

Geophysics