How to avoid force downcasting and unwrapping optionals without nested loops in Swift?

Question

I'm having a difficult time trying not to write nested loops whenever I avoid force downcasting and unwrapping optionals. Is there a way to do this?

Example:

var customers = [Customer]()
if response.result.isSuccess, let jsonDictionary = response.result.value as? NSDictionary {
    if let usersJSON = jsonDictionary.object(forKey: "users") as? [NSDictionary] {
        for customerJSON in usersJSON {
            if let customer = Customer.from(customerJSON) {
                customers.append(customer)
            }
        }
    }
}

completionHandler(customers)

Where are you using nested loops? There are no nested loops in the code you posted. — rmaddy, Apr 13 '17 at 22:23
And this is Swift. Why are you using `NSDictionary` instead of a Swift dictionary? — rmaddy, Apr 13 '17 at 22:24
Btw, if you really experiencing pain in parsing JSON, i would recommend looking into what this library does https://github.com/JohnSundell/Unbox — Zapko, Apr 13 '17 at 22:25

score 0 · Answer 1 · answered Apr 13 '17 at 22:16

You can also write like this:

guard response.result.isSuccess, 
   let jsonDictionary = response.result.value as? NSDictionary,
   let usersJSON = jsonDictionary.object(forKey: "users") as? [NSDictionary] else { completionHandler([]) }

completionHandler(usersJSON.flatMap(Customer.from))

How to avoid force downcasting and unwrapping optionals without nested loops in Swift?

1 Answers1