How to reset iOS-Charts animation in tableview cell - ios

Question

I am using a line chart from iOS-Charts in a custom tableview cell that expands on touch. I'm not loading the charts in cellForRow: since this loads all the charts in all the cells and kills scrolling performance, so I have it loading in didSelectRow:. The problem is that for some reason, the chart doesn't load the first time a user touches a cell and I have no idea why. Also, it seems like the chart animation starts when an expanded cell (that is currently showing a chart) is collapsed.
Here is my didSelectRow: and below is the charting func in my custom cell. I've been wrestling with this, any insight would be greatly appreciated!
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
let cell:CandDetailTableViewCell = tableView.cellForRowAtIndexPath(indexPath) as! CandDetailTableViewCell
// CALLS METHOD TO BUILD CHART WITH DATA I SAVED IN THESE ARRAYS
cell.setChart(dataForMonths, values: dataForRatings)
let previousIndexPath = selectedIndexPath
if indexPath == selectedIndexPath {
// if user taps cell that was already selected so it collapses
selectedIndexPath = nil
} else {
// when user selects new cell
selectedIndexPath = indexPath
}
var indexPaths:Array <NSIndexPath> = []
if let previous = previousIndexPath {
indexPaths += [previous]
}
if let current = selectedIndexPath {
indexPaths += [current]
}
if indexPaths.count > 0 {
tableView.reloadRowsAtIndexPaths(indexPaths, withRowAnimation: .Automatic)
}
tableView.scrollRectToVisible(tableView.rectForRowAtIndexPath(indexPath), animated: true)
}
Here is chart func in the tableview cell:
func setChart(dataPoints: [String], values: [Double]) {
var dataEntries: [ChartDataEntry] = []
for i in 0..<dataPoints.count {
let dataEntry = ChartDataEntry(value: values[i], xIndex: i)
dataEntries.append(dataEntry)
}
let lineChartDataSet = LineChartDataSet(yVals: dataEntries, label: "Rating")
let lineChartData = LineChartData(xVals: dataPoints, dataSet: lineChartDataSet)
analyticsView.data = lineChartData
analyticsView.xAxis.labelPosition = .Bottom
analyticsView.backgroundColor = UIColor.whiteColor()
analyticsView.userInteractionEnabled = false
analyticsView.drawGridBackgroundEnabled = false
analyticsView.drawBordersEnabled = false
analyticsView.leftAxis.enabled = false
analyticsView.rightAxis.enabled = false
analyticsView.xAxis.gridLineWidth = 0.0
analyticsView.xAxis.axisLineColor = UIColor.clearColor()
analyticsView.legend.enabled = false
// Removes the description text off the chart
analyticsView.descriptionText = ""
analyticsView.animate(xAxisDuration: 2.0, yAxisDuration: 2.0)
}

Answer 1

first, put analyticsView.data = lineChartData after you setup your chat view. It needs to read some properties to do some math;
second, when and where you add the chart view into the cell's content view?
Also, it seems a little strange when you call tableView.reloadRowsAtIndexPaths(indexPaths, withRowAnimation: .Automatic) in didSelectRow, I assume you should add the chart view into cell's content view here, not reload data? Because it will trigger another cellForItemAtIndexPath and override what you have done?
basically when you do addSubView, it will start drawing the chart. You can add a break point at addSubView and drawRect of the line chart view, and see if it can break when you hit the cell.
You can also manually trigger a redraw by chartView.setneedsDisplay
Update:
If you want to reset animation, call the animate API again and maybe another setNeedsDisplay