How to set different colors for intervals on LineChart?

[jmamegroot]

I m using Charts Library (swift) and I need to add a specific color as background color for each interval in line chart like heartrate zones (see url image). Any one has an idea?

http://imgur.com/a/kNpBj

[thierryH91200]

look at Grid background #645 i think that this is the same problem but with the soluce

[liuxuan30]

Thank you @thierryH91200