How to create Dictionary that can hold anything in Key? or all the possible type it capable to hold

Question

I want to create a Dictionary that does not limit the key type (like NSDictionary)

So I tried

var dict = Dictionary

        

Answer 1

Hashable is just a protocol so you can't specify it directly as a type for the Key value. What you really need is a way of expressing "any type T, such that T implements Hashable. This is handled by type constraints in Swift:

func makeDict(arr: T[]) {
  let x = Dictionary()
}

This code compiles.

AFAIK, you can only use type constraints on generic functions and classes.