问题
hi I have an array of coordinates data like this, which is retrieved from an API call, and I use a for loop to append the data into an array like this:
extension TripListViewController: UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
performSegue(withIdentifier: Constants.segueTripListToTripMap, sender: indexPath)
tableView.deselectRow(at: indexPath, animated: true)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == Constants.segueTripListToTripMap {
if let destinationVC = segue.destination as? TripMapViewController,
let indexPath = sender as? IndexPath {
for i in 0...(tripList[indexPath.section][indexPath.row].coordinates.count-1) {
self.coodinates.append(tripList[indexPath.section][indexPath.row].coordinates[i])
}
destinationVC.coodinatePoints = coodinates
}
} else {
if let destinationVC = segue.destination as? PolicyOverviewViewController,
let indexPath = sender as? IndexPath {
// do something
}
}
}
}
it has an error... I don't know how to pass this array to the variable I declared in another screen, the data type seem doesn't match.
The original data type look like this:
struct Trips: Codable {
let id: String
let userId: String
let coordinates: [Coordinates]
}
struct Coordinates: Codable {
let lat: Double?
let lng: Double?
let time: String?
}
[
["time": "timestampes"
"lat": 40.213
"lon": 5.203],
["time": "timestampes"
"lat": 40.213
"lon": 5.203],
["time": "timestampes"
"lat": 40.213
"lon": 5.203],
["time": "timestampes"
"lat": 40.213
"lon": 5.203]
]
how can I pass this data into my draw route function's point variable. it's currently hardcoded with some dummy data.
func drawRoutes() {
var points = [CLLocationCoordinate2DMake(51.079980, 4.349850),
CLLocationCoordinate2DMake(51.079060, 4.350830),
CLLocationCoordinate2DMake(51.078210, 4.350490),
CLLocationCoordinate2DMake(51.077750, 4.350890),
CLLocationCoordinate2DMake(51.076760, 4.354600),
CLLocationCoordinate2DMake(51.075130, 4.351000),
CLLocationCoordinate2DMake(51.073800, 4.350690),
CLLocationCoordinate2DMake(52.071850, 4.352880),
CLLocationCoordinate2DMake(52.069320, 4.355940),
CLLocationCoordinate2DMake(52.069120, 4.356130),
CLLocationCoordinate2DMake(52.069120, 4.356130),
CLLocationCoordinate2DMake(52.069120, 4.356130),
CLLocationCoordinate2DMake(52.068570, 4.356950),
CLLocationCoordinate2DMake(52.067840, 4.358440),
CLLocationCoordinate2DMake(52.066730, 4.357490),
CLLocationCoordinate2DMake(52.066590, 4.358680),
CLLocationCoordinate2DMake(52.066580, 4.358680),
CLLocationCoordinate2DMake(52.066580, 4.358680),
CLLocationCoordinate2DMake(52.066830, 4.357490),
CLLocationCoordinate2DMake(52.067600, 4.358520),
CLLocationCoordinate2DMake(52.068650, 4.356920),
CLLocationCoordinate2DMake(52.074330, 4.350360),
CLLocationCoordinate2DMake(52.075520, 4.351880),
CLLocationCoordinate2DMake(52.076950, 4.355350),
CLLocationCoordinate2DMake(52.078000, 4.350690),
CLLocationCoordinate2DMake(52.078010, 4.350710),
CLLocationCoordinate2DMake(52.079520, 4.351560),
CLLocationCoordinate2DMake(52.080680, 4.350220),
CLLocationCoordinate2DMake(52.080760, 4.348890),
CLLocationCoordinate2DMake(52.079890, 4.349980),
CLLocationCoordinate2DMake(52.079890, 4.350000)]
let polygon = MKPolyline(coordinates: &points, count: points.count)
self.mapView.addOverlay(polygon)
self.mapView.setVisibleMapRect(polygon.boundingMapRect, animated: true)
var startPoint = points[0]
for i in 1...(points.count-1) {
guard let request = createRequest(c1:startPoint, c2:points[i]) else { return }
let directions = MKDirections(request: request)
directions.calculate { [unowned self] (response, error) in
guard let response = response else { return }
let routes = response.routes
let bestDest = routes[0]
startPoint = points[i]
}
}
}
thanks a lot !
回答1:
You can use map to convert your coordinates
let points: [CLLocationCoordinate2D] = coordinates.compactMap {
guard let latitude = $0.lat, let longitude = $0.lng else { return nil }
return CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
}
This will convert all Coordinates objects that has both a latitude and a longitude given.
Are you sure the properties can be null in Coordinates, if not the above can be simplified to
let points: [CLLocationCoordinate2D] = coordinates.map {
CLLocationCoordinate2D(latitude: $0.lat, longitude: $0.lng)
}
回答2:
based on Joakim's answer, I figured out the complete solution for this:
So what do you do to pass some coordinates data from screen A (say you have a tableView) to screen B (you have the map).
So in screen A (viewControllerA):
You define the coordinates variable (according to your data model of course, should be an array usually)
var coordinates = [Coordinates]()
Then in your UITableViewDelegate extension, you append your coordinates into your coordinates array. Then use prepare segue to pass it to your destination viewController.
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == Constants.segueTripListToTripMap {
if let destinationVC = segue.destination as? TripMapViewController,
let indexPath = sender as? IndexPath {
for i in 0...(tripList[indexPath.section][indexPath.row].coordinates.count-1) {
self.coordinates.append(tripList[indexPath.section][indexPath.row].coordinates[i])
}
destinationVC.coordinatePoints = coordinates
coordinates = []
}
} else {
if let destinationVC = segue.destination as? PolicyOverviewViewController,
let indexPath = sender as? IndexPath {
// do something
}
}
}
In your screen B (where you map is). You define the variable to catch the data pass from screen A, which is coordinatePoints
var coordinatePoints: [Coordinates]?
then in your draw route function (or whatever name you call it). You convert this coordinatePoints into CLLocationCoordinate2D type like below:
func drawRoutes() {
var points:[CLLocationCoordinate2D] = coordinatePoints?.compactMap {
guard let latitude = $0.lat, let longitude = $0.lng else { return nil }
return CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
} ?? [CLLocationCoordinate2DMake(52.3676, 4.9041)]
let polygon = MKPolyline(coordinates: &points, count: points.count)
self.mapView.addOverlay(polygon)
self.mapView.setVisibleMapRect(polygon.boundingMapRect, animated: true)
var startPoint = points[0]
for i in 1...(points.count-1) {
guard let request = createRequest(c1:startPoint, c2:points[i]) else { return }
let directions = MKDirections(request: request)
directions.calculate { [unowned self] (response, error) in
guard let response = response else { return }
let routes = response.routes
let bestDest = routes[0]
startPoint = points[i]
}
}
}
there you go, when you click the table cell in screen A, it should pass the right coordinates into screen B and plot it on the map.
来源：https://stackoverflow.com/questions/64622152/pass-array-of-map-coordinates-to-a-draw-a-route-on-map-in-swift