Swift: unwrapping cause swift compile slowly

Question

In func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell!{

this line of code makes swift compile

Answer 1

You need to do unwrapping when your types are declared as optionals. In swift an optional type is a type that may or may not have a value. For example i could declare a string as:

var collegeName : String?

The "?" at the end of type declaration shows that the collegeName may or may not have a value and in order to get that value you will have to unwrap it in order to get its value by using ! operator.

As far as i can tell in your case the name field is declared as a string while year , make and model are declared as optional strings that is why you need to unwrap those fields to get the value out of them.

You can also declared a type using "!" operator like:

var collegeName : String!

This means that this is an optional string but it is automatically unwrapped for you so you don't need to use the "!" afterwards to unwrap this optional.