Implementation of Core Plot DatePlot example not rendering lines - core-plot

Question

I'm attempting to add the DatePlot example of core-plot to a UIVisualEffectView. I have the graph rendering but for some reason I'm not seeing the actual line of data. I'm wondering if someone can help me see what I'm doing wrong. Below is my code. I'm calling set_up_chart, then add_chart_data, if that helps. (I've also tried calling add_chart_data before set_up_chart but get the same result.)
def graph
#graph ||= CPTXYGraph.alloc.initWithFrame(host_view.bounds)
end
def host_view
chart_frame = CGRect.new(
[0, 0],
[vibrancy_view.frame.size.width, vibrancy_view.frame.size.height]
)
#host_view ||= CPTGraphHostingView.alloc.initWithFrame(chart_frame)
end
def set_up_chart
# graph.applyTheme(CPTTheme.themeNamed(KCPTDarkGradientTheme))
host_view.backgroundColor = UIColor.clearColor
host_view.allowPinchScaling = false
whiteTextStyle = CPTMutableTextStyle.alloc.init
whiteTextStyle.color = CPTColor.whiteColor
whiteTextStyle.fontSize = 12.0
whiteTickStyle = CPTLineStyle.alloc.init
whiteTickStyle.lineColor = CPTColor.whiteColor
whiteTickStyle.lineWidth = 0.5
axisLineStyle = CPTMutableLineStyle.alloc.init
axisLineStyle.lineColor = CPTColor.whiteColor
axisLineStyle.lineWidth = 1.0
axisLineStyle.lineCap = KCGLineCapRound
host_view.hostedGraph = graph
graph.paddingLeft = 5.0
graph.paddingTop = 5.0
graph.paddingRight = 5.0
graph.paddingBottom = 5.0
graph.plotAreaFrame.paddingLeft = 32.0
graph.plotAreaFrame.paddingTop = 0.0
graph.plotAreaFrame.paddingRight = 0.0
graph.plotAreaFrame.paddingBottom = 22.0
# Plot space
plotSpace = graph.defaultPlotSpace
start_time = Time.now.to_i
plotSpace.xRange = CPTPlotRange.plotRangeWithLocation(0.0, length: 1)
y_range_length = ((event[:range_minimum]).abs + 1) + (event[:range_maximum] + 1)
y_start = event[:range_minimum] - 1
plotSpace.yRange = CPTPlotRange.plotRangeWithLocation(y_start, length: y_range_length)
plotSpace.delegate = self
axisSet = graph.axisSet
# X axis
x = axisSet.xAxis
x.labelingPolicy = CPTAxisLabelingPolicyAutomatic
x.majorIntervalLength = start_time
# set where the x-axis aligns itself
x.orthogonalPosition = y_start
x.minorTicksPerInterval = 0
x.labelOffset = 0.25
x.labelTextStyle = whiteTextStyle
x.titleTextStyle = whiteTextStyle
x.axisLineStyle = axisLineStyle
x.majorTickLineStyle = whiteTickStyle
x.minorTickLineStyle = whiteTickStyle
x.axisConstraints = CPTConstraints.constraintWithLowerOffset(0.0)
# x.labelOffset = 16.0
x.majorTickLength = 4.0
x.minorTickLength = 2.0
# x.tickDirection = CPTSignPositive
x.preferredNumberOfMajorTicks = 4.0
# x.majorGridLineStyle = majorGridLineStyle
# x.minorGridLineStyle = minorGridLineStyle
dateFormatter = NSDateFormatter.alloc.init
dateFormatter.setDateFormat("h:mm")
timeFormatter = CPTTimeFormatter.alloc.initWithDateFormatter(dateFormatter)
timeFormatter.referenceDate = reference_date
x.labelFormatter = timeFormatter
# Y axis
y = axisSet.yAxis
y.labelingPolicy = CPTAxisLabelingPolicyAutomatic
y.orthogonalPosition = 0.0
# y.majorGridLineStyle = majorGridLineStyle
# y.minorGridLineStyle = minorGridLineStyle
y.minorTicksPerInterval = 1
y.labelOffset = 0.25
y.axisConstraints = CPTConstraints.constraintWithLowerOffset(0.0)
y.labelTextStyle = whiteTextStyle
y.titleTextStyle = whiteTextStyle
y.axisLineStyle = axisLineStyle
y.majorTickLineStyle = whiteTickStyle
# Remove minor ticks on y-axis
y.minorTickLineStyle = whiteTickStyle
# Create the plot
dataSourceLinePlot = CPTScatterPlot.alloc.init
dataSourceLinePlot.identifier = "Test"
dataSourceLinePlot.cachePrecision = CPTPlotCachePrecisionDouble
lineStyle = dataSourceLinePlot.dataLineStyle.mutableCopy
lineStyle.lineWidth = 3.0
lineStyle.lineColor = CPTColor.greenColor
dataSourceLinePlot.dataLineStyle = lineStyle
dataSourceLinePlot.dataSource = self
dataSourceLinePlot.delegate = self
graph.addPlot(dataSourceLinePlot)
end
def add_chart_data
if self.chart_data.count == 0
array = []
100.times do |n|
value = [-5,-1,0,1,5].sample
time = (Time.now.to_i - 100) + (5 * n)
data = {CPTScatterPlotFieldX => time, CPTScatterPlotFieldY => value}
array << data
self.chart_data = array
end
end
graph.reloadData
end
def numberOfRecordsForPlot(plot)
self.chart_data.count
end
def numberForPlot(plot, field: fieldEnum, recordIndex: index)
if self.chart_data[index]
if fieldEnum == CPTScatterPlotFieldX
self.chart_data[index][fieldEnum]
else
self.chart_data[index][fieldEnum]
end
end
end

Answer 1

The xRange for the plot space is being initialized to [0, 1] while the data is initialized to values between time - 125 and time - 75. All of the data points are outside this xRange.
Do you need to use the current time when computing the data points? If so, save it somewhere and use the same value when creating the data and configuring the plot space. If not, pick a constant starting point for the data and create the xRange to match.