Flatten an Array of Arrays in Swift

Is there a counterpart in Swift to flatten in Scala, Xtend, Groovy, Ruby and co?

var aofa = [[1,2,3],[4],[5,6,7,8,9]]
aofa.flatten() // shall deliver [1,2,3,4,5,6,7,8,9] 

of course i could use reduce for that but that kinda sucks

var flattened = aofa.reduce(Int[]()){
    a,i in var b : Int[] = a
    b.extend(i)
    return b
}