Swift: Calling a function with parameters that may be nil - ios

Question

I'm trying to figure out if there is any shorter syntax in Swift for the last line here:
var startPosition: CLLocationCoordinate2D?
var latitude: Double?
var longitude: Double?
// ...
// Here I have skipped some code which may or may not assign values
// to "latitude" and "longitude".
// ...
if latitude != nil && longitude != nil {
startPosition = CLLocationCoordinate2DMake(latitude!, longitude!)
}
As you can see, I want to set the "startPosition" based on "latitude" and "longitude", if those values have been assigned. Otherwise, I accept that the "startPosition" will not be initialized.
I guess this must be possible with "if let" or something similar, but I have failed to figure out how. (I'm experienced in Objective-C, but have just started to learn Swift.)

Answer 1

This is not shorter, but you can simply do
if let latitude = latitude, let longitude = longitude {
startPosition = CLLocationCoordinate2D(latitude: latitude,
longitude: longitude)
}
Notice I used just CLLocationCoordinate2D, not CLLocationCoordinate2DMake. Swift provides constructors without the "make" to most common objects, so you shouldn't usually have to use "make" in constructors.

Answer 2

If you don't want to execute any code after if they are nil use a guard.
var startPosition: CLLocationCoordinate2D?
var latitude: Double?
var longitude: Double?
guard let latitude = latitude && longitude = longitude else {
return
}
startPosition = CLLocationCoordinate2DMake(latitude, longitude)

Answer 3

Clear way
if let latitude = latitude, longitude = longitude {
startPosition = CLLocationCoordinate2D(latitude: latitude,
longitude: longitude)
}
CLLocationCoordinate2D is a struct, it's better if you use the struct initializer. Notice there is only one "let" needed in the if statement.

Answer 4

If i understood the question correctly, you could say
var startPosition: CLLocationCoordinate2D?
var latitude: Double?
var longitude: Double?
if latitude != nil && longitude != nil {
startPosition = CLLocationCoordinate2DMake(latitude!, longitude!)
} else {
startPosition = nil
}