---
title: "Create and style clusters - Swift SDK | Mobile sdk | Mobile sdk ios | Ios"
description: "Generate and visualize point clusters using iOS Swift SDK."
---

> For AI agents: a documentation index is available at [/llms.txt](https://docs.maptiler.com/llms.txt). Markdown versions of all pages are available by appending .md to any URL.

# Create and style clusters - Swift SDK

The following SwiftUI example demonstrates how to use the built-in Swift SDK functions to generate and visualize a cluster map of points.

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Add an `MTGeoJSONSource` to the map’s style with `isCluster: true`. Adjust the `clusterRadius` and `clusterMaxZoom` parameters as needed.

To render clusters, create an `MTCircleLayer` for the cluster bubbles. Use step expressions based on point count to determine color and size, and apply a cluster filter. Add an `MTSymbolLayer` above to display the cluster count using `MTTextToken.pointCountAbbreviated`. Finally, create another `MTCircleLayer` for individual (unclustered) points, and apply an unclustered filter to show only those.

```swift
import SwiftUI
import CoreLocation
import MapTilerSDK

struct ClusteringSwiftUIExample: View {
  @State private var mapView = MTMapView(
    options: MTMapOptions(center: CLLocationCoordinate2D(latitude: 20, longitude: 0), zoom: 0.3)
  )

  private let sourceId = "earthquakes"
  private let clustersLayerId = "clusters"
  private let clusterCountLayerId = "clusterCount"
  private let unclusteredLayerId = "unclusteredPoint"

  // Note: Best practice is to set the API key at app startup (App/Scene or AppDelegate).
  // It's set here for standalone copy-paste convenience.
  init() {
    Task { await MTConfig.shared.setAPIKey("YOUR_API_KEY") }
  }

  var body: some View {
    MTMapViewContainer(map: mapView) {
      // Add clustered source via DSL so it exists before layers are added.
      MTGeoJSONSource(
        identifier: sourceId,
        url: URL(string: "https://docs.maptiler.com/sdk-js/assets/earthquakes.geojson")!,
        isCluster: true,
        clusterMaxZoom: 14,
        clusterRadius: 50
      )
    }
    .referenceStyle(.dataviz)
    .styleVariant(.dark)
    .didInitialize { Task { await setupClustering() } }
  }

  private func setupClustering() async {
    guard let style = mapView.style else { return }

    // Cluster bubbles (circles)
    let clusters = MTCircleLayer(identifier: clustersLayerId, sourceIdentifier: sourceId)
    clusters.strokeColor = .white
    clusters.strokeWidth = 2
    clusters.pitchAlignment = .viewport
    clusters.pitchScale = .map
    clusters.filterExpression = MTFilter.clusters()
    clusters.color = .expression(MTExpression.step(
      input: MTExpression.get(.pointCount),
      default: .color(UIColor(hex: "#51bbd6") ?? .systemTeal),
      stops: [
        (100, .color(UIColor(hex: "#f1f075") ?? .systemYellow)),
        (750, .color(UIColor(hex: "#f28cb1") ?? .systemPink))
      ]
    ))
    clusters.radius = .expression(MTExpression.step(
      input: MTExpression.get(.pointCount),
      default: .number(20),
      stops: [ (100, .number(30)), (750, .number(40)) ]
    ))
    try? await style.addLayer(clusters)

    // Cluster counts (symbols)
    let count = MTSymbolLayer(identifier: clusterCountLayerId, sourceIdentifier: sourceId)
    count.filterExpression = MTFilter.clusters()
    count.textField = MTTextToken.pointCountAbbreviated.rawValue
    count.textSize = 12
    count.textAllowOverlap = true
    count.textAnchor = .center
    count.textFont = ["DIN Offc Pro Medium", "Arial Unicode MS Bold"]
    count.textColor = .white
    try? await style.addLayer(count)

    // Unclustered points (circles)
    let unclustered = MTCircleLayer(identifier: unclusteredLayerId, sourceIdentifier: sourceId)
    unclustered.color = .color(UIColor(hex: "#11b4da") ?? .systemBlue)
    unclustered.radius = .number(4)
    unclustered.strokeColor = .white
    unclustered.strokeWidth = 1
    unclustered.filterExpression = MTFilter.unclustered()
    try? await style.addLayer(unclustered)
  }
}
```

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## UIKit in Swift

If you are working with UIKit in Swift refer to the [Swift UIKit clustering example](https://github.com/maptiler/maptiler-sdk-swift/blob/main/Examples/Clustering%2BUIKit.swift)