Questions

Hi there,

I’m trying to display little icons as axis labels using the LabelProvider API and NSAttributedString (with NSTextAttachmet). Is this supported? Here’s a minimal example:

import UIKit
import Foundation
import SciChart
import SciChart.Protected.SCILabelProviderBase

class ViewController: UIViewController {

    private lazy var chart: SCIChartSurface = {
        let c = SCIChartSurface(frame: .zero)
        c.xAxes.add(items: SCINumericAxis())

        let yAxis = SCINumericAxis()
        yAxis.labelProvider = SymbolLabelProvider()
        c.yAxes.add(items: yAxis)
        return c
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        SCIChartSurface.setRuntimeLicenseKey(myLicenseKey)

        view.addSubview(chart)
        chart.translatesAutoresizingMaskIntoConstraints = false
        let guide = self.view.safeAreaLayoutGuide
        NSLayoutConstraint.activate([
            chart.leadingAnchor.constraint(equalTo: guide.leadingAnchor),
            chart.trailingAnchor.constraint(equalTo: guide.trailingAnchor),
            chart.topAnchor.constraint(equalTo: guide.topAnchor),
            chart.bottomAnchor.constraint(equalTo: guide.bottomAnchor),
        ])
    }
}

class SymbolLabelProvider: SCILabelProviderBase<SCINumericAxis> {

    lazy var numberFormatter: NumberFormatter = {
        let f = NumberFormatter()
        f.allowsFloats = true
        f.maximumFractionDigits = 2
        return f
    }()

    init() {
        super.init(axisType: ISCINumericAxis.self)
    }

    override func formatLabel(_ dataValue: ISCIComparable!) -> ISCIString! {

        let intValue = Int(dataValue.toDouble())
        let font = UIFont.init(descriptor: axis.tickLabelStyle.fontDescriptor, size: UIFont.systemFontSize * 4)

        if intValue.isMultiple(of: 2) {
            let i = UIImage(systemName: "circle", withConfiguration: UIImage.SymbolConfiguration(font: font))
            return NSAttributedString(attachment: NSTextAttachment(image: i!))
        } else {
            let attributes: [NSAttributedString.Key: Any] = [
                .font: font,
                .foregroundColor: UIColor.yellow,
            ]
            return NSAttributedString(string: numberFormatter.string(for: dataValue.toDouble())!, attributes: attributes)
        }
    }
}

See attached screenshot for the result.

If this is not supported: any suggestions / ideas for a workaround?

Thanks
—Matthias