iOS Font Customization only works with Noto Sans Regular

[michaelmedellin]

Hi, I'm attempting to customize the font I'm using for one of my symbol layers but I'm running into an issue where if I use anything other than Noto Sans Regular the layer doesn't render at all — symbols and text. Notably, if I don't include the textFontNames property on the layer the layer will also not render.

For example, I've tried without success:
layer.textFontNames = NSExpression(forConstantValue: ["Comic Sans MS"])
layer.textFontNames = NSExpression(forConstantValue: ["Noto Sans Bold"])
layer.textFontNames = NSExpression(forConstantValue: ["Trebuchet MS"])
layer.textFontNames = NSExpression(forConstantValue: ["Helvetica Neue"])

Snippet of my current code:

var markerLayer: MLNSymbolStyleLayer {
        let layer = MLNSymbolStyleLayer(identifier: markerId, source: source)
        
        layer.iconImageName = NSExpression(forKeyPath: "iconKey")
        layer.iconColor = NSExpression(forConstantValue: UIColor.red)
        layer.iconAllowsOverlap = NSExpression(forConstantValue: true)
        layer.iconIgnoresPlacement = NSExpression(forConstantValue: true)
        layer.iconScale = NSExpression(forConstantValue: 1)
        
        layer.text = NSExpression(forKeyPath: showCallSigns ? "callSign" : "name")
        layer.textFontNames = NSExpression(forConstantValue: ["Noto Sans Regular"])
        layer.textFontSize = NSExpression(forConstantValue: 13)
        layer.textHaloWidth = NSExpression(forConstantValue: 1.5)
        layer.textHaloColor = NSExpression(forConstantValue: UIColor.secondarySystemBackground)
        layer.textColor = NSExpression(forConstantValue: UIColor.label)

Unsure if I'm hitting a bug or just not customizing the font correctly. I've looked through the documentation but not sure I've found anything conclusive.

Running iOS 18.0 and Maplibre 6.17.1

[louwers]

What do you have set as glyphs URL?

Fonts need to be made available in a MapLibre font pbf file e.g. using https://github.com/maplibre/font-maker

[michaelmedellin]

https://{{my domain}}/fonts/{fontstack}/{range}.pbf is set in the style.json that's configured for the basemap. Our app then dynamically adds new layers on top of the basemap that are outside of the original style sheet.

That glyphs URL is where I have Noto Sans Regular, Italic, and Medium.

I was under the impression that a layer that I add to an existing style could use a client-side font that ships with iOS? Perhaps the original style glyphs URL is overriding the client-side font declaration?

[louwers]

At this moment, that only applies to CJK fonts.

In the near future that may change though.

[michaelmedellin]

@louwers thanks kindly for the response!

[louwers]

Welcome!

We will have a release out soon that allows you to use TrueType fonts.