qsort

qsort.m

#import <Foundation/Foundation.h>

int stringComp(const void *a, const void *b) {
    NSString *aO = *(NSString *__autoreleasing*)a;
    NSString *bO = *(NSString *__autoreleasing*)b;
    
    return [aO caseInsensitiveCompare:bO];
}


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSString * __autoreleasing *array;
        array = (NSString* __autoreleasing*) malloc(sizeof(NSString*)*20);
        
        for(int i = 0; i < 20; i++) {
            array[i] = [NSString stringWithFormat:@"%d", arc4random() % 100];
        }
        
        qsort(array, 20, sizeof(NSString*), stringComp);
        
        NSArray* result = [NSArray arrayWithObjects:array count:20];
        free(array);

        NSLog(@"%@", result);
    }
    return 0;
}

qsort.swift

import Foundation

extension Comparable {
    static func compare(l: UnsafePointer<Void>, r: UnsafePointer<Void>) -> Int32 {
        let leftPointer: Self = UnsafePointer(l).memory
        let rightPointer: Self = UnsafePointer(r).memory
        if leftPointer < rightPointer { return -1 }
        if leftPointer == rightPointer { return 0 }
        return 1
    }
    
}

func cmp(thunk: UnsafeMutablePointer<Void>, l: UnsafePointer<Void>, r: UnsafePointer<Void>) -> Int32 {
    let comparisonFunction: (UnsafePointer<Void>, UnsafePointer<Void>) -> Int32 = UnsafePointer(thunk).memory
    return comparisonFunction(l,r)
}

func quickSort<A: Comparable>(var array: [A]) -> [A] {
    var myFunc = A.compare
    qsort_r(&array, array.count, strideof(A), &myFunc, cmp)
    return array
}


let myArray = ["Hello", "ABC", "world", "abc"]
print(quickSort(myArray))
print(myArray)