Swift chunked collection batches of fixed size

import Foundation

func chunked<C: Collection>(_ items: C, size: Int) -> [[C.Element]] {
    guard size > 0 else { return [] }
    var batches: [[C.Element]] = []
    var start = items.startIndex
    while start < items.endIndex {
        let end = items.index(start, offsetBy: size, limitedBy: items.endIndex) ?? items.endIndex
        batches.append(Array(items[start..<end]))
        start = end
    }
    return batches
}