how to set up array for multi annotations with swift

Question

How should the array below be set. Im trying to add multiple annotations onto my map. I was able to find the code below on stackoverflow but they did not show how to set up the array.

var objects = [ 
                //how should the array be setup here 
              ]

for objecters in objects!{
    if let latit = objecters["Coordinates"]["Latitude"]{
        self.latitudepoint = latit as! String
        self.map.reloadInputViews()
    }
    else {
        continue
    }
    if let longi = objecters["Coordinates"]["Longitude"]{
        self.longitudepoint = longi as! String
        self.map.reloadInputViews()
    }
    else {
        continue
    }
    var annotation = MKPointAnnotation()
    var coord = CLLocationCoordinate2D(latitude: Double(self.latitudepoint)!,longitude: Double(self.longitudepoint)!)
    mapView.addAnnotation(annotation)
}

Answer 1

You could do, for example:

let locations = [
    ["title": "New York, NY",    "latitude": 40.713054, "longitude": -74.007228],
    ["title": "Los Angeles, CA", "latitude": 34.052238, "longitude": -118.243344],
    ["title": "Chicago, IL",     "latitude": 41.883229, "longitude": -87.632398]
]

for location in locations {
    let annotation = MKPointAnnotation()
    annotation.title = location["title"] as? String
    annotation.coordinate = CLLocationCoordinate2D(latitude: location["latitude"] as! Double, longitude: location["longitude"] as! Double)
    mapView.addAnnotation(annotation)
}

Or, alternatively, use a custom type, e.g.:

struct Location {
    let title: String
    let latitude: Double
    let longitude: Double
}

let locations = [
    Location(title: "New York, NY",    latitude: 40.713054, longitude: -74.007228),
    Location(title: "Los Angeles, CA", latitude: 34.052238, longitude: -118.243344),
    Location(title: "Chicago, IL",     latitude: 41.883229, longitude: -87.632398)
]

for location in locations {
    let annotation = MKPointAnnotation()
    annotation.title = location.title
    annotation.coordinate = CLLocationCoordinate2D(latitude: location.latitude, longitude: location.longitude)
    mapView.addAnnotation(annotation)
}

Or you can replace that for loop with map:

let annotations = locations.map { location -> MKAnnotation in
    let annotation = MKPointAnnotation()
    annotation.title = location.title
    annotation.coordinate = CLLocationCoordinate2D(latitude: location.latitude, longitude: location.longitude)
    return annotation
}
mapView.addAnnotations(annotations)

Finally, it is worth noting that you can make your custom object conform to MKAnnotation protocol, and then you can use it directly, bypassing MKPointAnnotation type entirely:

class Location: NSObject, MKAnnotation {
    dynamic var title: String?
    dynamic var subtitle: String?
    dynamic var coordinate: CLLocationCoordinate2D

    convenience init(title: String? = nil, subtitle: String? = nil, latitude: Double, longitude: Double) {
        self.init(title: title, subtitle: subtitle, coordinate: CLLocationCoordinate2D(latitude: latitude, longitude: longitude))
    }

    init(title: String? = nil, subtitle: String? = nil, coordinate: CLLocationCoordinate2D) {
        self.title = title
        self.subtitle = subtitle
        self.coordinate = coordinate

        super.init()
    }
}

let locations = [
    Location(title: "New York, NY",    latitude: 40.713054, longitude: -74.007228),
    Location(title: "Los Angeles, CA", latitude: 34.052238, longitude: -118.243344),
    Location(title: "Chicago, IL",     latitude: 41.883229, longitude: -87.632398)
]

mapView.addAnnotations(locations)

Note, the use of the dynamic qualifier is optional, but is useful if you intend to make your annotation views draggable and/or have annotation mutations be reflected dynamically on the map.