objective-c - swift中的map()方法

Question

为什么执行次数是5times而不是4times

Answer 1

What debugging tool are you using? I changed the map’s closure:

var arr = [1,2,3,4]
let mapArr = arr.map({
  (i: Int) -> Int in
    print("a")
    return i * 2
})

Only 4 'a's are output.
My platform is: Swift on Ubuntu.