Generic function to sort array of class by properties

Question

I want to create a generic function to sort an array of classes based on a property passed.

For example, I have these classes

public class Car {
             


        

Answer 1

Expanding on @MartinR answer to allow increasing (<) or decreasing (>) sort:

---

extension MutableCollection where Self: RandomAccessCollection {
    mutating func sort(_ keyPath: KeyPath, by areInIncreasingOrder: ((T, T) -> Bool) = (<)) {
        sort(by: { areInIncreasingOrder($0[keyPath: keyPath], $1[keyPath: keyPath]) })
    }
}

---

extension Sequence {
    func sorted(_ keyPath: KeyPath, by areInIncreasingOrder: ((T,T)-> Bool) = (<)) -> [Element] {
        sorted(by: { areInIncreasingOrder($0[keyPath: keyPath], $1[keyPath: keyPath]) })
    }
}

---

people.sorted(\.age)
people.sorted(\.age, by: >)

cars.sorted(\.manufacturer)
cars.sorted(\.manufacturer, by: >)

edit/update:

To suport sorting a custom object by an optional property that conforms to Comparable protocol:

---

extension MutableCollection where Self: RandomAccessCollection {
    mutating func sort(_ keyPath: KeyPath>, by areInIncreasingOrder: ((T, T) -> Bool) = (<)) {
        sort(by: {
            switch ($0[keyPath: keyPath], $1[keyPath: keyPath]) {
            case let (lhs?, rhs?): return areInIncreasingOrder(lhs, rhs)
            case (.none, _): return false
            case (_, .none): return true
            }
        })
    }
}

---

extension Sequence {
    func sorted(_ keyPath: KeyPath>, by areInIncreasingOrder: ((T,T)-> Bool) = (<)) -> [Element]  {
        sorted(by: {
            switch ($0[keyPath: keyPath], $1[keyPath: keyPath]) {
            case let (lhs?, rhs?): return areInIncreasingOrder(lhs, rhs)
            case (.none, _): return false
            case (_, .none): return true
            }
        })
    }
}

---

Usage:

array.sort(\.optionalStringProperty) {
    $0.localizedStandardCompare($1) == .orderedAscending
}
print(array)