How to use swift flatMap to filter out optionals from an array

Question

I\'m a little confused around flatMap (added to Swift 1.2)

Say I have an array of some optional type e.g.

let possibles:[Int?] = [nil, 1, 2, 3, nil, nil         


        

Answer 1

Since this is something I seem to end up doing quite a lot I'm exploring a generic function to do this.

I tried to add an extension to Array so I could do something like possibles.unwraped but couldn't figure out how to make an extension on an Array. Instead used a custom operator -- hardest part here was trying to figure out which operator to choose. In the end I chose >! to show that the array is being filtered > and then unwrapped !.

let possibles:[Int?] = [nil, 1, 2, 3, nil, nil, 4, 5]

postfix operator >! {}

postfix func >! (array: Array) -> Array {
    return array.filter({ $0 != nil }).map({ $0! })
}

possibles>!
// [1, 2, 3, 4, 5]