Dictionary error: Ambiguous reference to member '+' [duplicate]

Answer 1

As others have commented, this appears to be a bug. However, it seems like you are unlikely to encounter this, because it is quite unsafe to force unwrap a dictionary element like that. This works fine:

let dict = ["A": 1, "B": 2, "C": 3]

if
  let a = dict["A"],
  let b = dict["B"],
  let c = dict["C"]
{
  let sum = a + b + c
}

Answer 2

Another workaround:

let dict = ["A": 1, "B": 2, "C": 3]
let sum = 0 + dict["A"]! + dict["B"]! + dict["C"]!

Answer 3

This code has been compiled successfully:

let dict = ["A": 1, "B": 2, "C": 3]
let one = dict["A"]!
let two = dict["B"]!
let three = dict["C"]!
let sum = one + two + three

I guess, this problem related to complex expressions. You can read more about build time optimisation in this article.

Answer 4

You can resolve the error by wrapping dict["A"] with Int.

This will cast the value of the key "A" to an Int,allowing us to add properly.

let dict = ["A": 1, "B": 2, "C": 3]
let sum = Int(dict["A"]!) + Int(dict["B"]!) + Int(dict["C"]!)