MKAnnotationView has double optionals

Question

Created Dec ’15

Replies 3

Boosts 0

Participants 3

If I implement MKMapViewDelegate like so:

    func mapView(mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
        guard let item = view.annotation else { return }

and then I try to look at item.title, it's showing as a String?? instead of a String? in Xcode 7.1.1

If I control-click on annotation it says it's an MKAnnotation? like I'd expect. Control-clicking on that shows title defined like so, which looks correct to me. Is this a bug I need to report?

optional public var title: String? { get }

Answered by DTS Engineer in 91666022

You end up with two levels of optionality because:

within the MKAnnotation protocol, the
```
title
```
property is optional
if that property is implemented, the value it returns is optional

I’m not sure if there’s a nicer way to access

title

but the following seems to work:

if let os = item.title, let s = os {
    print(s)
}

Share and Enjoy
—
Quinn "The Eskimo!"
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Boost

Answer 1

DTS Engineer OP

Apple

Dec ’15

Accepted Answer

You end up with two levels of optionality because:

within the MKAnnotation protocol, the
```
title
```
property is optional
if that property is implemented, the value it returns is optional

I’m not sure if there’s a nicer way to access

title

but the following seems to work:

if let os = item.title, let s = os {
    print(s)
}

Share and Enjoy
—
Quinn "The Eskimo!"
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

0

Answer 2

Gargoyle OP

Dec ’15

I ended up doing the double let as well, thanks. So the first one is basically an "if they implemented the optional getter" and then the second one is "does it have a value".

Makes sense, even though it's super ugly 🙂

0

Answer 3

jawbroken OP

Dec ’15

If you just want to collapse the double optional you can use “?? nil” which gets you to a single level of optionality.

0