Swift map change points if change SegmentedControl - ios

Question

I'm trying to work with Mapbox.
I have created a point on my map and show from file
I want that when SegmentedControl is changed, item.type is changed accordingly and get correct data
For example if press 0 case -> make 0 == item.type
I create custom points
func addItemsToMap(features: [MGLPointFeature]) {
guard let style = mapView.style else { return }
let source = MGLShapeSource(identifier: "mapPoints", features: features, options: nil)
style.addSource(source)
let colors = [
"black": MGLStyleValue(rawValue: UIColor.black)
]
let circles = MGLCircleStyleLayer(identifier: "mapPoints-circles", source: source)
circles.circleColor = MGLSourceStyleFunction(interpolationMode: .identity,
stops: colors,
attributeName: "color",
options: nil)
circles.circleRadius = MGLStyleValue(interpolationMode: .exponential,
cameraStops: [2: MGLStyleValue(rawValue: 5),
7: MGLStyleValue(rawValue: 8)],
options: nil)
circles.circleStrokeWidth = MGLStyleValue(rawValue: 2)
circles.circleStrokeColor = MGLStyleValue(rawValue: UIColor.white)
style.addLayer(circles)
}
Put data to mapbox
func test(number: Int) {
guard let documentsDirectoryUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
let urlBar = documentsDirectoryUrl.appendingPathComponent("Persons.json")
do {
let jsonData = try Data(contentsOf: urlBar)
//Переводим их в модель
let result = try JSONDecoder().decode(CollectionTest.self, from: jsonData)
let coll: CollectionTest = result
let features = parseJSONItems(collection: coll, number: number)
addItemsToMap(features: features)
print(features)
} catch { print("Error while parsing: \(error)") }
}
Get data from file
func parseJSONItems(collection: CollectionTest, number: Int) -> [MGLPointFeature] {
var features = [MGLPointFeature]()
for item in collection.prices {
if item.type == number {
...get data to annotation and location
let feature = MGLPointFeature()
feature.coordinate = coordinate
feature.title = "\(name)"
feature.attributes = [
"color" : color,
"name" : "\(name)"
]
features.append(feature)
}
}
}}}
}
return features
}
I need to change number from 0 to 4, because in data I have type from 0 to 4 and points need to change from 0-4 if SegmentedControl is changed
in SegmentedControl I have
#objc func change(sender: UISegmentedControl) {
switch sender.selectedSegmentIndex {
case 0:
test(number: 0)
case 1:
test(number: 1)
case 2:
ttest(number: 2)
case 3:
test(number: 3)
case 4:
test(number: 4)
default:
test(number: 2)
}
}
In viewDidLoad:
override func viewDidLoad() {
super.viewDidLoad()
styleToggle.addTarget(self, action: #selector(change(sender:)), for: .valueChanged)
test(number: 2)
}
When app run - works good and show all data == type 2
But when I change button in SegmentedControl to case 0 or others - I get a crash and in console prints
Terminating app due to uncaught exception
'MGLRedundantSourceIdentifierException', reason: 'Source mapPoints already exists'
What am I doing wrong? How to fix this?

Answer 1

It looks like you are trying to add a source to your map that already exists. In order to avoid this message, you will want to either:
Check for the existence of a source before adding it to your style. In your use case, maybe name your sources mapPoints-circles-\(number). If the source already exists, reuse it.
Add the source to the map one time (preferably within the initial -mapView:didFinishLoadingStyle:). In order to create new layers from it layer, you can access the source from the map's style.
If the points come from a source with an identifier my-source, you would try:
guard let source = style.source(withIdentifier: "my-source") else { return }

Answer 2

when clicking a segment, remove all markers which are already present in the map
then add new markers
You can use map.removeLayer(marker); to remove the marker (an ILayer object).