如何在 Swift 中按数字和字母顺序对数组进行排序

Question

Say I have an array:

var array = ["5C", "4D", "2H", "13S", "4C", "5H"]

How would I be able to sort this array so that the new array would have the last character sorted alphabetically, then the previous numerical values sorted numerically such as:

["4C", "5C", "4D", "2H", "5H", "13S"]

I am relatively new to coding in general and have a very basic grasp of syntax. Other searches have shown me how to sort numerically using the.sorted function and.ascendingOrder, but I couldn't find a solution that could sort both alphabetically and numerically.

Answer 1

You have to write your own comparator which is pretty handy in Swift.

If the last character is the same sort the string without the last character numerically otherwise sort by the last character

let array = ["5C", "4D", "2H", "13S", "4C", "5H"]

let sortedArray = array.sorted { (str1, str2) -> Bool in
    if str1.suffix(1) == str2.suffix(1) {
        return str1.dropLast().localizedStandardCompare(str2.dropLast()) == .orderedAscending
    } else {
        return str1.suffix(1) < str2.suffix(1)
    }
}

// ["4C", "5C", "4D", "2H", "5H", "13S"]

Answer 2

EDIT:

My answer shows how to use sorted() to sort an array of strings into "numeric" order. It is not quite what the OP asked.

To the OP: You should accept vadian's answer. His was the first correct answer.

However, I spend some time in my answer explaining Swift closure syntax, so I am going to leave the answer.

---

You can use the array method sorted() , which takes a closure that compares pairs of objects and returns true if the first item should come first.

Then you can use the NSString method compare(options:) to do a "numeric" string comparison, where sequences of digits are treated as numbers inside the string.

Here is a working code snippet that will sort your array:

var array = ["5C", "4D", "2H", "13S", "4C", "5H"]

let sorted = array.sorted (by: { (first: String, second: String) -> Bool in
    return first.compare(second, options: .numeric) == .orderedAscending
})

The function sorted() is a "higher order function`, or a function that takes another function as a parameter. For an array of strings, that function takes 2 strings, and returns a Bool. It actually takes a closure rather than a function, where a closure is an "anonymous function" (a function with no name.)

Adapting vadian's code that gives the CORRECT answer to my snippet, it would look like this:

var array = ["5C", "4D", "2H", "13S", "4C", "5H"]

let sorted = array.sorted (by: { (first: String, second: String) -> Bool in
    if first.suffix(1) == second.suffix(1) {
        return first.dropLast.compare(second, options: .numeric) == .orderedAscending

    } else {
        return first.suffix(1) < second.suffix(1)
    }
})

You can rewrite the above with several shortcuts:

With a "trailing closure" you skip the () that contains the closure as a parameter and just provide the closure in braces after the function name.

You can skip the declaration of the parameters and return type of the closure, and skip the return statement:

let sorted = array.sorted { $0.compare($1, options: .numeric) == .orderedAscending }

For more complex code like vadian's that gives the correct answer, I suggest not using positional parameters like that. Using local variables like first and second make the code easier to read.

I suggest studying the chapter on Closures in Apple's Swift iBooks carefully until you understand the various ways that closures can be expressed and their different shortcut syntaxes. It's confusing at first, and using closures is fundamental to using Swift.

Answer 3

Welcome to StackOverflow!

What do these numbers represent? I would create a struct to model that "thing" (I'll call it Thing for now), and function that can parse a String into a Thing , like so:

struct Thing: Equatable { // FIXME: Name me something descriptive
    let number: Int // FIXME: Name me something descriptive
    let letter: Character // FIXME: Name me something descriptive

    static func parse(from string: String) -> Thing? {
        let numberSegment = string.prefix(while: { $0.isNumber })
        guard !numberSegment.isEmpty,
            let number = Int(numberSegment) else { return nil }

        let letterSegement = string.drop(while: { $0.isNumber })
        guard letterSegement.count == 1,
            let letter = letterSegement.first else { return nil }

        return Thing(number: number, letter: letter)
    }
}

Then, you can just conform to Comparable , defining how you want things to be sorted, by defining the comparison operator < :

extension Thing: Comparable {
    static func < (lhs: Thing, rhs: Thing) -> Bool {
        return (lhs.letter, lhs.number) < (rhs.letter, rhs.number)
    }
}

From there, it's just a matter of parsing all your strings into Thing s, and sorting them:

let array = ["5C", "4D", "2H", "13S", "4C", "5H"]

let things = array.map { Thing.parse(from: $0)! }
print("Before sorting:")
things.forEach { print("\t\($0)") }

let sortedThings = things.sorted()
print("\nAfter sorting:")
sortedThings.forEach { print("\t\($0)") }

Output:

Before sorting:
    Thing(number: 5, letter: "C")
    Thing(number: 4, letter: "D")
    Thing(number: 2, letter: "H")
    Thing(number: 13, letter: "S")
    Thing(number: 4, letter: "C")
    Thing(number: 5, letter: "H")

After sorting:
    Thing(number: 4, letter: "C")
    Thing(number: 5, letter: "C")
    Thing(number: 4, letter: "D")
    Thing(number: 2, letter: "H")
    Thing(number: 5, letter: "H")
    Thing(number: 13, letter: "S")

Answer 4

Welcome to StackOverflow!

this is my solution hope it works for you, I just organize first the numbers and next comparate with the alphabeth to create a new array:

var array = ["5C", "4D", "2H", "13S", "4C", "5H"]
    array = array.sorted { $0.numbersValues < $1.numbersValues }
    let str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    var newArrray: [String] = [] 
    for letter in str {
            for value in array {
                if value.lettersValues.hasPrefix(String(letter)) {
                       newArrray.append(value)
                }
            }
    }

Don't forget include this helpers methods in your project

    extension String {

        var lettersValues: String {
            return self.components(separatedBy: CharacterSet.decimalDigits).joined()
        }

        var numbersValues: String {
            return self.filter { "0"..."9" ~= $0 }
        }
    }