Removing from array during enumeration in Swift?

In Swift 2 this is quite easy using enumerate and reverse.

var a = [1,2,3,4,5,6]for (i,num) in a.enumerate().reverse() {    a.removeAtIndex(i)}print(a)

You might consider filter way:

var theStrings = ["foo", "bar", "zxy"]// Filter only strings that begins with "b"theStrings = theStrings.filter { $0.hasPrefix("b") }

The parameter of filter is just a closure that takes an array type instance (in this case String) and returns a Bool. When the result is true it keeps the element, otherwise the element is filtered out.

In Swift 3 and 4, this would be:

With numbers, according to Johnston's answer:

var a = [1,2,3,4,5,6]for (i,num) in a.enumerated().reversed() {   a.remove(at: i)}print(a)

With strings as the OP's question:

var b = ["a", "b", "c", "d", "e", "f"]for (i,str) in b.enumerated().reversed(){    if str == "c"    {        b.remove(at: i)    }}print(b)

However, now in Swift 4.2 or later, there is even a better, faster way that was recommended by Apple in WWDC2018:

var c = ["a", "b", "c", "d", "e", "f"]c.removeAll(where: {$0 == "c"})print(c)

This new way has several advantages:

1. It is faster than implementations with filter.
2. It does away with the need of reversing arrays.
3. It removes items in-place, and thus it updates the original array instead of allocating and returning a new array.