gistfile1.txt

extension Array {
  func toDict<K,V>(map: (Element) -> (K, V)?) -> [K: V] {
    var dict = [K: V]()
    for element in self {
      if let (key, value) = map(element) {
        dict[key] = value
      }
    }
    return dict
  }
}

// to use
let t = [(name: "tom", age: 23),(name: "jim", age: 32),(name:"bill", age: 45)]
let g = t.toDict { ($0.name, $0.age) }
// ["tom": 23, "jim": 32, "bill": 45]