converting String to Int failure [duplicate]

Question

I've two variables number and number2 with String value, I want to convert those Strings to Int and add to each other,but the compiler returns error: Binary operator '+' cannot be applied to two 'Int?' operands.

var n1 = "6"
var number = n1 + "5"
Int(number)

var n2 = "3"
var number2 = n2 + "5"
var finalNumber = Int(number2) + Int(number)
print(finalNumber)

I want summary of Int numbers and not strings. expected result: 19

Answer 1

Because converting a String to an Int can be a failing operation, say converting A into an Int, you are using a failable initializer.

This means that you are getting Int? as a result. In your first example, you get a result of Optional(65) when printed. In playgrounds, the optional's value, of just 65, is shown instead.

The problem arrises that you can't add Int? together with the + operator, only two Ints.

You can fix the problem by providing a default value if the conversion failed and the result is nil:

var finalNumber = Int(number2) ?? 0 + (Int(number) ?? 0)