相当于NSDictionary的objectsForKeys for Swift词典

Question

对于Swift词典，是否有相当于NSDictionary的objectsForKeys:notFoundMarker:？

Answer 1

事实上，Martin R建议使用map()是一个很好的方法，而且非常好！

myKeys.map({ myDict[$0] })

将返回一组可选项！

Answer 2

extension Dictionary {
  public subscript(k1: Key, k2: Key, ks: Key...) -> [Value?] {
    get { return ([k1, k2] + ks).map { k in self[k] } }
    set { for (k, v) in zip([k1, k2] + ks, newValue) { self[k] = v } }
  }
}

let dict = [1:"a", 2:"b", 4:"d"]

dict[1, 2, 3, 4] // ["a", "b", nil, "d"]