How is optional binding used in swift?

Question

In swift the following syntax is allowed for flow control

if let constantName = someOptional {
    statements
}

In this context what are the semantics of the truth value context ?

Is expression chaining (like below) permitted ?

if let constantName = someOptional &&  constantName2 = someOptional2 {
    statements
}

If so, does the boolean expression short circuit ?

Answer 1

First someOptional is checked to see if it's nil or has data. If it's nil, the if-statement just doesn't get executed. If there's data, the data gets unwrapped and assigned to constantName for the scope of the if-statement. Then the code inside the braces is executed.

if let constantName = someOptional {
    statements
}

There's no way to chain this functionality in one if-statement. let constantName = someOptional does not directly evaluate to a boolean. It's best to think of "if let" as a special keyword.