Better Swift array sorting method?

Question

I'm trying to sort an int array inside of Swift from greatest to least. The code I used is:

Array(data.keys).sorted(by: { $0 > $1 })

The array given is an array with integers 1 through 1,000. The results are:

999, 998, 997 ... 991, 990, 99, 989 ... 802, 801, 800, 80, 8, 799, 798 ...

The results I want are:

999, 998, 997 ... 991, 990, 989 ... 802, 801, 800, 799, 798 ...

You don't have an array of integers. You have an array of strings. — rmaddy
– rmaddy, Commented Jul 11, 2018 at 2:39

Leo Dabus · Accepted Answer · 2018-07-11 02:50:05Z

3

Your dictionary keys are strings not integers. You can sort them comparing those keys using numeric options as follow:

let sorted = data.keys.sorted { 
    $0.compare($1, options: .numeric) == .orderedDescending 
}

edited Jul 11, 2018 at 2:50

answered Jul 11, 2018 at 2:42

Leo Dabus

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2 Comments

Alexander Over a year ago

How does this compare (performance-wise) to mapping to int first, then sorting? (Assuming an [Int] is acceptable final result type)

TheLukeGuy Over a year ago

Gosh I feel dumb, sorry for wasting your time haha

Mark · Accepted Answer · 2018-07-11 02:32:37Z

-2

The sort is calculating based on ASCII String Values,

Type Coersion to Int....

answered Jul 11, 2018 at 2:32

Mark

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2 Comments

Alexander Over a year ago

Swift doesn't coerce Strings/Characters to ASCII (for one, because they're utf encoded (8/16/32, I don't remember), and it doesn't do almost any coercions implicitly, in general.

Mark Over a year ago

Poor use of language by me... I was just pointing out that the sort was occurring based on String/character rather than Int sort which is what the correct solution does....

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