MKMapView: How do I set mapType? (beginner question)

Question

Created May ’21

Replies 3

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Hi

I am an absolute beginner in Swift.

A friend helped me setup a test app that displays a map using Map Kit. This is the part that creates the actually map:

Code Block class KMLViewerViewController: UIViewController, MKMapViewDelegate {
    let map = MKMapView()
    // etc. ...
    }

I tried to set mapType to hybridFlyover in different ways, like this for instance:

Code Block let map = MKMapView(.mapType = .hybridFlyover )

But everything returns an error...
Can any one help me, please?
Where can I find an explanation of swift syntax?

Answered by Claude31 in 674250022

There is no conenience init for MKMapView that let you declare the mapType as an init parameter.

You should thus write:

Code Block import MapKit
class KMLViewerViewController: UIViewController, MKMapViewDelegate {
    let map = MKMapView()
    // etc. ...
    override func viewDidLoad() {
        super.viewDidLoad()
        map.mapType = .hybridFlyover
    }
}

Note that
map.mapType = .hybridFlyover
must be inside a func ; it cannot be at the class level just after etc…

Unless you declare it as a computed var:

Code Block     var map : MKMapView {
        let aMap = MKMapView()
        aMap.mapType = .hybridFlyover
        return aMap
    }

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Answer 1

Claude31 OP

May ’21

Accepted Answer

There is no conenience init for MKMapView that let you declare the mapType as an init parameter.

You should thus write:

Code Block import MapKit
class KMLViewerViewController: UIViewController, MKMapViewDelegate {
    let map = MKMapView()
    // etc. ...
    override func viewDidLoad() {
        super.viewDidLoad()
        map.mapType = .hybridFlyover
    }
}

Note that
map.mapType = .hybridFlyover
must be inside a func ; it cannot be at the class level just after etc…

Unless you declare it as a computed var:

Code Block     var map : MKMapView {
        let aMap = MKMapView()
        aMap.mapType = .hybridFlyover
        return aMap
    }

0

Answer 2

Claude31 OP

May ’21

But everything returns an error...
Can any one help me, please?
Where can I find an explanation of swift syntax?

A few more comments:

when you have error, please post the error
what you tried:

Code Block let map = MKMapView(.mapType = .hybridFlyover )

is a wrong syntax, as you have noticed.

When you call a class initialiser that has parameters, it would be something like this syntax:

Code Block let map = MKMapView(mapType: .hybridFlyover)

No dot before the label for the parameter
no equal but colon sign
But this does not work here because no such initialiser exist (you could subclass MKMapView and create such a convenience init)

This works:

Code Block import MapKit
class MyOwnMKMapView : MKMapView {
    convenience init(mapType: MKMapType) {
        self.init()
        self.mapType = mapType
    }
}
class KMLViewerViewController: UIViewController, MKMapViewDelegate {
    
    let map = MyOwnMKMapView(mapType : .hybridFlyover )  // You use your subclass
    // etc. ...
}

0

Answer 3

HenrikRo OP

May ’21

Thank you very much for your 2 answers!

0