Sorting string arrays in Swift

Question

let names = ["Chris", "Alex", "Ewa", "Barry", "Daniella"]
func backwards(s1: String, s2: String) -> Bool {
    return s1 > s2
}
var reversed = names.sort(backwards)
print(reversed)
var ascending = names.sort({ (s1: String, s2: String) -> Bool in
    return s1 < s2
})
print(ascending)
let sortAscending = { (s1: String, s2: String) -> Bool in
    return s1 < s2
}
ascending = names.sort(sortAscending)

I am suppose to sort this code according to the number of characters they have from the most to the least. For example, Daniella has 8 characters so she will be fist in the list. The output I am suppose to get is ["Daniella", "Barry", "Chris", "Alex", "Ewa"]

Hey man, you might also want to check our sort vs sorted discussion below — I don't think your code compiles at all :( — Paulo Mattos
– Paulo Mattos, Commented Apr 28, 2017 at 2:32
i used var sorted = ascending.sort { $0.characters.count > $1.characters.count } and it works — Androlitas
– Androlitas, Commented Apr 28, 2017 at 2:42
@LeoDabus ...not okay: he is using sort and expecting a return value, makes no sense, even when in-place sorting mutable collections. BTW, does Swift returns an empty tuple (aka, Void) in such scenarios? That would explain why his code compiles... — Paulo Mattos
– Paulo Mattos, Commented Apr 28, 2017 at 2:58

Paulo Mattos · Accepted Answer · 2017-04-28 03:23:28Z

1

Try this:

let names = ["Chris", "Alex", "Ewa", "Barry", "Daniella"]
let sortedNames = names.sorted { $0.characters.count > $1.characters.count }
print(sortedNames)

Should I sort or should I sorted? Use sort to order the original array in-place, if declared as a var; if let your code won't even compile. Use sorted to leave your original array alone and return a new, properly sorted array; works on let and var.

edited Apr 28, 2017 at 3:23

answered Apr 28, 2017 at 2:18

Paulo Mattos

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7 Comments

Leo Dabus Over a year ago

names is immutable. You need to use sortedmethod

Paulo Mattos Over a year ago

I know :) Was thinking about a good name for the sorted array, but gave up haha...

Andy Ibanez Over a year ago

He means that you need to call names.sorted instead of names.sort. I don't think your current code compiles.

Leo Dabus Over a year ago

He could use sort also but he would need to declare the array as variable

Androlitas Over a year ago

ok thanks! to get my output i just have to replace names with ascending.

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