GK Grid Path Finding issue

import GameplayKit

var nodes = [GKGridGraphNode]()

let maxSize = 3

//Here I'm filling the elements of the grid
for i in 0..<maxSize {
  for j in 0..<maxSize {

    let node = GKGridGraphNode(gridPosition: vector_int2(Int32(i), Int32(j)))
    nodes.append(node)
  }
}

let graph = GKGridGraph(nodes)
let start = GKGridGraphNode(gridPosition: vector_int2(0,0))
let end = GKGridGraphNode(gridPosition: vector_int2(2,2))

let path = graph.findPath(from: start, to: end) //It returns an empty array
print(path)