Two Sum in Swift

main.swift

func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
  var dictionary = [Int:Int]();
  
  for index in 0 ..< nums.count {
    let complement = target - nums[index];
    if dictionary.keys.contains(complement) && dictionary[complement] != index {
      return [dictionary[complement]!,index];
    }
    dictionary[nums[index]] = index
  }
  
  return [];
}