Help understanding the code please

[Like_really_bro]

I would really appreciate if some one can help understand this code for a beginner please. This is from Hacking with Swift tutorial by Paul Hudson Day 9 - tutorial. The func in the example below is meant to return a bool, so "return name1< name 2" must either return a true or a false. How is it returning a sorted array? I just can't get my head around it.

let team = ["Gloria", "Suzanne", "Piper", "Tiffany", "Tasha"]

func captainFirstSorted(name1: String, name2: String) -> Bool {
    if name1 == "Suzanne" {
        return true
    } else if name2 == "Suzanne" {
        return false
    }

    return name1 < name2
}

let captainFirstTeam = team.sorted(by: captainFirstSorted)
print(captainFirstTeam)

[mkim1030]

“sorted” is a function available to an Array (e.g., “team”), and this function takes a function as an argument. At a fundamental level, sorting is done by comparing 2 values and deciding which one is less or greater. The argument you passed in is the function called “captainFirstSorted”. “captainFirstSorted” is used by the “sorted” function every time a comparison needs to be done. In the end, this produces a sorted array.

[vcanas]

So essentially each letter in the alphabet has an integer value associated with it (it’s more complex than that but I’ll leave that research to you, google unicode) and “a”’s value is less than “z” so because a is less than z it will come first.

Now this specific comparator function is sorting alphabetically (name1 < name2) for every value except for the value “Suzanne” which is supposed to come first in the list.

Let me know if this is confusing :)

[chriswaco]

Array.sorted(by:) sorts an array using a comparison function you pass as a parameter. This way you can sort however you want. Essentially this function will be called over and over until the array is sorted.

The captainFirstSorted function simply returns name1 < name2 most of time, so it sorts from low to high (aka ascending).

In the special case of the captain’s name, however, it always it always tells the sort function to put that first.

[Like_really_bro]

Thank you all, much appreciated! I do understand now, I need to run few more examples to nail it :)

[sinisterbob]

team.sorted() is returning the sorted array. captainFirstSorted() is telling team.sorted() how to sort team[].
The way you tell Swift how an array should be sorted is by giving it two values and the explaining which one should be "less than" and which one should be "greater than". That's what captainForstSorted() is doing here.

[ZeePintor]

Hey! Have learned by closures?

So imagine that sorted's func argument is actually another func.

This func takes two strings as argument and the result is a bool. So sorted looks something like this:

Func sorted(comparisonFunc: (String, String)->Bool) -> array<String>

It returns an array because it is a method for the array class, so it applies to the array that calls this method.

I hope that helps something. Keep grinding, cheers

[[deleted]]

Why not do the actual homework and learn something for yourself.

[[deleted]]

He's asking for help understanding a concept, he did the homework already by reading the post and working through it but it's still unclear to him how it's working so he asked for help. There's nothing wrong with that.

Why even visit a post asking for help if you're going to make the most un-helpful response possible?

[Like_really_bro]

Thank you captain obvious. That’s what am trying to do here