iOS and Xamarin.iOS Charting Documentation - SciChart iOS Charts and Xamarin Charts SDK v2.x
Axis Labels - TextFormatting

All Axis obey standard formatting strings via the TextFormatting property, e.g. some our examples include:

Objective C:

[axis setTextFormatting:@"dd/MM/yyyy"];

Swift:

let axis = SCIDateTimeAxis()
axis.textFormatting = "dd/MM/yyyy"