Updating data in LineChart takes up to 30 seconds

[cbgrey]

I have a view with a line chart on it and it displays initial data immediately from viewDidLoad(). However, if I update the chart later after an API call is complete, changes to the line chart data can take 30 seconds to be seen.

I am updating the chart via:
chart.data = new_data

Time to update is not affected by the number of new or existing data points. I've tried between 2 and 100 data points.

Calling notifyDataSetChanged() has no affect.

I cannot see what the chart object is doing during the time I am waiting for the update to be reflected.

[cbgrey]

Developer failure. I was calling the update on a background thread. Moved the update to the main/UI thread and all works as expected.