Cannot invoke initializer for type 'Double' with an argument list of type '(String?)'

Question

I have two issues:

let amount:String? = amountTF.text

1. amount?.characters.count <= 0

It\'s giving error

Answer 1

Your string is optional because it had a '?", means it could be nil, means further methods would not work. You have to make sure that optional amount exists then use it:

WAY 1:

// If amount is not nil, you can use it inside this if block.

if let amount = amount as? String {

    let am = Double(amount)
}

WAY 2:

// If amount is nil, compiler won't go further from this point.

guard let amount = amount as? String else { return }

let am = Double(amount)