Actually, it’s quite simple with Swift. As mentioned in the Apple’s doc, you can initialize an array with the same repeated value like this:
With old Swift version:
var threeDoubles = [Double](count: 3, repeatedValue: 0.0)
Since Swift 3.0:
var threeDoubles = [Double](repeating: 0.0, count: 3)
which would give:
[0.0, 0.0, 0.0]