Swift short hand for assignment of Optional values - swift

Question

I'm new to Swift and I'm wondering if there's a 'short hand' form of assigning Optional values to non-optional values without doing if nil check.
For example if I've got an Optional closure:
var onTap: (() -> Void)?
I can later on call this via
onTap?()
The ? let's me skip the nil check and force unwrap.
But I'm curious if something exists for values that are not clousre. For example
var oldTransform: CGAffineTransform?
var someTransform: CGAffineTransform //non optional
and later on, I decide to assign oldTransform to someTransform I have to
if (oldTransform != nil) {
someTransform = oldTransform!
}
Is there a pattern that's less verbose to do the above (kinda of like the ?)?

Answer 1

Yes, of course. You could use if let as below:
if let unwrappedOldTransForm = oldTransform {
someTransform = unwrappedOldTransForm
}
When you check with if let, it will unwrap the value for you and check if it can set the value of oldTransform to unwrappedOldTransForm. If the value is nil you will be able to handle the error by adding an else condition as below:
if let unwrappedOldTransForm = oldTransform {
someTransform = unwrappedOldTransForm
} else {
// handle if oldTransform is nil
}

Answer 2

In the case of a function, as you know, "calling" a nil function (like onTap?()) has no effect - but for an assignment to a non-optional type you need to supply a definite non-optional value. For that you can use the nil-coalescing operator ?? like so:
var optionalString: String?
// ... maybe set optionalString ...
var realString: String = optionalString ?? "<some default value>"
In your example, it would be
someTransform = oldTransform ?? CGAffineTransform(...) // some default - say Identity
or even, as commentator #user28434 suggests
someTransform = oldTransform ?? someTransform // assuming someTransform already initialised
which will only change someTranform if oldTransform isn't nil.
In each case, the left hand operand of ?? will be assigned if is non-nil, otherwise the right hand side operand will be assigned.