如何按数字和字母值对 swift 中的字符串数组进行排序？

Question

I'm trying to sort an array that is listed as such:

let array = ["02:00 AM", "01:00 AM", "01:00 PM", "01:01 AM", "01:01 PM", "03:00 AM"]

It's a series of times that I can add/update in my userDefaults for reminders, however I want it sorted not only by the time but by the AM/PM value. that way the array looks like this:

["01:00 AM", "01:01 AM", "02:00 AM", "03:00 AM", "01:00 PM","01:01 PM"]

How can I do this? Using .sort() on the array doesn't work since that will just sort by time, but I specifically want the AM strings before the PM strings. I have the array as a String since I thought it would be easier, but I'm seeing that this may not be be best way about it.

Answer 1

Filter by 12 & AM, then sort. Filter by 12 & PM, then sort. Then join the 2 arrays.

let array = ["12:00 AM", "12:02 PM", "02:00 AM", "01:00 AM", "01:00 PM", "01:01 AM", "01:01 PM", "03:00 AM"]

We need to consider that the #12 will impact sorting. So you need to filter out all times with 12, sort them, and place them in front.

let amc = array.filter { $0.hasPrefix("12") }.filter { $0.hasSuffix("AM") }.sorted(by: <) + array.filter { !$0.hasPrefix("12") }.filter { $0.hasSuffix("AM") }.sorted(by: <)
let pmc = array.filter { $0.hasPrefix("12") }.filter { $0.hasSuffix("PM") }.sorted(by: <) + array.filter { !$0.hasPrefix("12") }.filter { $0.hasSuffix("PM") }.sorted(by: <)
let comb = amc + pmc
print(comb) // prints ["12:00 AM", "01:00 AM", "01:01 AM", "02:00 AM", "03:00 AM", "12:02 PM", "01:00 PM", "01:01 PM"]

With this exercise, it's clear that using Date is the best approach.

Answer 2

Building on @nighttalker 's answer you could get it in one line using sorted(by: <) .

Then the code would be:

let array = ["02:00 AM", "01:00 AM", "01:00 PM", "01:01 AM", "01:01 PM", "03:00 AM"]
let sortedArray = array.filter { $0.contains("AM") }.sorted(by: <) + array.filter { $0.contains("PM") }.sorted(by: <)

but as Arkku said you probably should use the Date type and make it conform to Comparable.

(I am not yet able to comment, so had to submit it this way)

Answer 3

let morningTimes = arrayOfTimes.filter{$0.contains("AM") && !$0.contains("12:")}.sorted()
let dayTimes = arrayOfTimes.filter{$0.contains("12:") && $0.contains("AM")}.sorted() + morningTimes
let nightTimes = arrayOfTimes.filter{$0.contains("PM") && !$0.contains("12:")}.sorted()
let allTimes = dayTimes + arrayOfTimes.filter{$0.contains("12:") && $0.contains("PM")}.sorted() + nightTimes

Answer 4

You can pass sort a block and implement the comparison logic there, eg:

var array = ["02:00 AM", "01:12 AM", "01:00 PM", "01:01 AM", "01:01 PM", "03:00 AM", "12:15 AM", "12:30 AM", "12:01 PM", "12:30 PM" ]
array.sort { s1, s2 in
    let isAM1 = s1.contains("AM")
    let isAM2 = s2.contains("AM")
    return isAM1 && !isAM2 || ((isAM1 == isAM2) && s1 < s2)
}

The comparison block should return true if and only if the first argument is to be sorted before the second. This is implemented here such that either the first is AM and the second is PM, or both are the same AM/PM and the first has an earlier time.

PS You might consider using Date objects instead of strings in the first place (you can always format them back into strings as needed).

Edit : If your strings use the convention where "12:00 PM" is noon and "12:00 AM" is midnight, such times would be sorted incorrectly by the above. You can sort of fix that by testing for s1.hasPrefix("12:") and inverting the "is AM" status:

if s1.hasPrefix("12:") {
    isAM1 = !isAM1
}
if s2.hasPrefix("12:") {
    isAM2 = !isAM2
}

Even this approach sorts 12:59 AM last instead of right before 01:00 AM – you can fine-tune the comparison if this is an issue. However, I think this complexity alone is sufficient reason to use Date objects (or your own Comparable time holders) rather than strings. Assuming you are unwilling to switch to a 24-hour clock. =)