How does addEntry method update LineChart in real time?

I am using iOS charts to display a simple cube line chart and want to update the graph every second with new messages. I tried using the addEntry method to dynamically add a value to the end of the array, and I verified that the data is indeed successfully added to the array after every second. However, the chart itself is not updated. I looked at the MPAndroidChart documentation and did not set a method to call any update method after the first call to the addEntry method. I see in another section of the documentation that there is an invalidate () method on the Chart object that updates the chart, however I don't have such an option when I access the Chart object and don't know if this is required.

Sample code:

var set1 = lineChartView.data?.getDataSetByIndex(0)
var index = set1?.entryCount
var value = arc4random_uniform(14) + 1
var chartEntry = ChartDataEntry(value: Float(value), xIndex: index!)

set1?.addEntry(chartEntry)

      

        
        
        
      

    

In the demo project, charts are modified using a slider control, but in this example, it just recreates the data and reloads the chart.data object, rather than dynamically modifying the original DataSet as I am trying to do.

Any help on what I need to do or where I need to look is greatly appreciated.

xcode 6.3

swift 1.2

iOS 8.3

iOS-Chart 2.1.0