How to find the index of an item in a multidimensional array swiftily?

Question

Let\'s say I have this array:

let a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

Now I want something like this:

public func indices         


        

Answer 1

Version accepting a closure, similar to index(where:), so there it is usable on the array of any elements, not only Equatable

extension Array where Element : Collection, Element.Index == Int {
  func indices(where predicate: (Element.Iterator.Element) -> Bool) -> (Int, Int)? {
    for (i, row) in self.enumerated() {
      if let j = row.index(where: predicate) {
        return (i, j)
      }
    }
    return nil
  }
}

Use like this:

let testArray = [[1,2,3], [4,5,6], [7,8]]

let testNumber = 6

print(testArray.indices(of: testNumber))
print(testArray.indices{$0 == testNumber})

Optional((1, 2))
Optional((1, 2))

Also, it can be used with IndexPath:

extension Array where Element : Collection, Element.Index == Int {
  func indexPath(where predicate: (Element.Iterator.Element) -> Bool) -> IndexPath? {
    for (i, row) in self.enumerated() {
      if let j = row.index(where: predicate) {
        return IndexPath(indexes: [i, j])
      }
    }
    return nil
  }
}