Always display vertical scrolling indicator on horizontal bar chart

[Carielle]

I have a horizontal bar chart that scrolls vertically so I can display many bars at a reasonable width. However, depending on the number of bars in the chart, it isn't obvious that the chart scrolls vertically, and I'm worried that my users will think that some of their data is missing because they don't realize the chart scrolls vertically. Is there a way I can force a vertical scrolling indicator to always be displayed in the chart, so it is clear to my users that the chart scrolls?

[liuxuan30]

The scrolling feature is based on CoreGraphics, not UIScrollView, so there is no indicators at all if I were correct.
By default, bar chart will show all data entries, and when user zooms in, it can scroll then. If you zooms in by code in the first place, you might want to add some hint for your users, or something indicates it can scroll.

[KovtunOleg]

I know it is late answer, but I just faced the same problem, so I implemented my own scroll horizontal scroll indicator using chart delegate method:

chart.delegate = self

extension MyChartView: ChartViewDelegate {
    private func showScrollIndicator(_ show: Bool) {
        UIView.animate(withDuration: 0.3, delay: show ? 0 : 3, animations: {
            self.scrollIndicator.alpha = show ? 1.0 : 0.0
        }, completion: { _ in
            self.scrollIndicator.isHidden = !show
        })
        if show {
            showScrollIndicator(false)
        }
    }

    func chartTranslated(_ chartView: ChartViewBase, dX: CGFloat, dY: CGFloat) {
        let maxTransX = (viewPortHandler.scaleX - 1) * viewPortHandler.contentWidth
        let maxOffsetX = chartView.frame.width - scrollIndicator.frame.width
        scrollIndicatorLeadingConstraint.constant = (-viewPortHandler.transX / maxTransX) * maxOffsetX
        showScrollIndicator(true)
    }
}