SortedMerged.swift

struct Item: Identifiable {
  let id: String
  let date: Date
}

let referenceDate = Date(timeIntervalSince1970: 1711282131)
let original: [Item] = [
  Item(id: "1", date: referenceDate.addingTimeInterval(1.0)),
  Item(id: "2", date: referenceDate.addingTimeInterval(2.0)),
  Item(id: "3", date: referenceDate.addingTimeInterval(3.0)),
  Item(id: "4", date: referenceDate.addingTimeInterval(4.0)),
  Item(id: "5", date: referenceDate.addingTimeInterval(5.0)),
]
let other: [Item] = [
  Item(id: "3", date: referenceDate.addingTimeInterval(1.5)),
  Item(id: "7", date: referenceDate.addingTimeInterval(2.5)),
  Item(id: "4", date: referenceDate.addingTimeInterval(4.0)),
  Item(id: "5", date: referenceDate.addingTimeInterval(5.5)),
  Item(id: "6", date: referenceDate.addingTimeInterval(8.0)),
]
let result = original.sortedMerged(with: other, areInIncreasingOrder: { $0.date < $1.date })
result.forEach { item in
  print("\(item.id) - \(item.date.timeIntervalSince(referenceDate))")
}
// 1 - 1.0
// 3 - 1.5
// 2 - 2.0
// 7 - 2.5
// 4 - 4.0
// 5 - 5.5
// 6 - 8.0