我想知道如何将单元附加到动态的 Core Plot 轴，如下所示。不幸的是，这并不像遍历标签和附加文本那么容易（我相信是由于图层操作和渲染）。有人知道该怎么做吗？
CPTXYAxis *x = axisSet.xAxis;
x.orthogonalCoordinateDecimal = CPTDecimalFromDouble(self.plotSpace1.xRange.minLimitDouble);//Where the Y Axis meets the X axis
x.majorIntervalLength = CPTDecimalFromDouble(200.0);//Interval for X Axis
x.minorTicksPerInterval = 0;
// x.tickDirection = CPTSignNone;
// x.axisLineStyle = axisLineStyle;
// x.majorTickLength = 12.0;
// x.majorTickLineStyle = axisLineStyle;
// x.minorTickLength = 8.0;
x.title = cYards;
x.titleTextStyle = axisTitleTextStyle;
x.titleOffset = 25.0;
x.axisConstraints = [CPTConstraints constraintWithLowerOffset:0.0];
// Label y with an automatic labeling policy.
axisLineStyle.lineColor = [CPTColor greenColor];
CPTXYAxis *y = axisSet.yAxis;
y.labelingPolicy = CPTAxisLabelingPolicyAutomatic;
y.preferredNumberOfMajorTicks = 11;
y.majorIntervalLength = CPTDecimalFromDouble(100.0);
y.minorTicksPerInterval = 0;
y.tickDirection = CPTSignNegative;
y.axisLineStyle = axisLineStyle;
y.majorTickLineStyle = axisLineStyle;
y.orthogonalCoordinateDecimal = CPTDecimalFromDouble(self.plotSpace1.xRange.minLimitDouble);
y.title = cInches;
y.titleTextStyle = axisTitleTextStyle;
y.titleOffset = 30.0;
// Label y2 with an equal division labeling policy.
axisLineStyle.lineColor = [CPTColor orangeColor];
CPTXYAxis *y2 = [[CPTXYAxis alloc] init];
y2.coordinate = CPTCoordinateY;
y2.plotSpace = self.plotSpace2;
y2.orthogonalCoordinateDecimal = CPTDecimalFromDouble(self.plotSpace1.xRange.maxLimitDouble);//Where the Y Axis meets the X axis
y2.preferredNumberOfMajorTicks = 8;
y2.majorIntervalLength = CPTDecimalFromDouble(200.0);
y2.minorTicksPerInterval = 0;
y2.tickDirection = CPTSignPositive;
y2.axisLineStyle = axisLineStyle;
y2.majorTickLineStyle = axisLineStyle;
y2.title= cFps;
y2.titleTextStyle = axisTitleTextStyle;
y2.titleOffset = 30.0;