如何在CorePlot中的plotspace上设置边界？

Question

我正在尝试使用Core-Plot在同一图表上绘制多个散点图。它们具有相同的x轴（时间），但我希望它们彼此独立地绘制。例如，对于两个图，我希望屏幕被分成两部分，上部显示一个图，下部显示另一个（我打算最终绘制实时多通道输入）。像这样的东西：

我尝试修改以下链接中给出的教程，以使用两个图块空间而不是一个：

http://www.raywenderlich.com/13271/how-to-draw-graphs-with-core-plot-part-2

但是，没有设置图表空间边界的功能。函数xRange和yRange改变了轴的范围，但两个图块空间仍占据整个屏幕。

以下是一段代码片段，其中显示了我尝试完成设置边界的两种方式：

-(void)configurePlots {

//Get graph and plot space
CPTGraph *graph = self.hostView.hostedGraph;
CPTXYPlotSpace *aaplPlotSpace = (CPTXYPlotSpace *)graph.defaultPlotSpace;

//**Setting xRange and yRange doesn't work**

aaplPlotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromCGFloat(0.0)
                                                            length:CPTDecimalFromCGFloat(graph.bounds.size.width)];
aaplPlotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromCGFloat(0.0)
                                                    length:CPTDecimalFromCGFloat((graph.bounds.size.height)/3)];



CPTXYPlotSpace *googPlotSpace = [[CPTXYPlotSpace alloc] init];
googPlotSpace.xRange = aaplPlotSpace.xRange;
googPlotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromCGFloat((graph.bounds.size.height)/3)
                                                    length:CPTDecimalFromCGFloat((graph.bounds.size.height)/3)];


[graph addPlotSpace:googPlotSpace];


//Create Plots

//**Trying to set bounds using initWithFrame doesn't work either**

CGRect rect = CGRectMake(0.0, 0.0, graph.bounds.size.width, graph.bounds.size.height/2);
CPTScatterPlot *aaplPlot = [[CPTScatterPlot alloc] initWithFrame:rect];
aaplPlot.dataSource = self;
aaplPlot.identifier = CPDTickerSymbolAAPL;
CPTColor *aaplColor = [CPTColor redColor];
[graph addPlot:aaplPlot toPlotSpace:aaplPlotSpace];

rect = CGRectMake(0.0, graph.bounds.size.height/2, graph.bounds.size.width, graph.bounds.size.height/2);
CPTScatterPlot *googPlot = [[CPTScatterPlot alloc] initWithFrame:rect];
googPlot.dataSource = self;
googPlot.identifier = CPDTickerSymbolGOOG;
CPTColor *googColor = [CPTColor greenColor];
[graph addPlot:googPlot toPlotSpace:googPlotSpace];
//[graph addPlot:googPlot];

//Set up Plot space
[aaplPlotSpace scaleToFitPlots:[NSArray arrayWithObject:aaplPlot]];
CPTMutablePlotRange *xaRange = [aaplPlotSpace.xRange mutableCopy];
[xaRange expandRangeByFactor:CPTDecimalFromCGFloat(1.1f)];
aaplPlotSpace.xRange = xaRange;
CPTMutablePlotRange *yaRange = [aaplPlotSpace.yRange mutableCopy];
[yaRange expandRangeByFactor:CPTDecimalFromCGFloat(1.2f)];
aaplPlotSpace.yRange = yaRange;

//Create styles and symbols

CPTMutableLineStyle *aaplLineStyle = [aaplPlot.dataLineStyle mutableCopy];
aaplLineStyle.lineWidth = 2.5;
aaplLineStyle.lineColor = aaplColor;
aaplPlot.dataLineStyle = aaplLineStyle;
CPTMutableLineStyle *aaplSymbolLineStyle = [CPTMutableLineStyle lineStyle];
aaplSymbolLineStyle.lineColor = aaplColor;
CPTPlotSymbol *aaplSymbol = [CPTPlotSymbol ellipsePlotSymbol];
aaplSymbol.fill = [CPTFill fillWithColor:aaplColor];
aaplSymbol.lineStyle = aaplSymbolLineStyle;
aaplSymbol.size = CGSizeMake(6.0f, 6.0f);
aaplPlot.plotSymbol = aaplSymbol;

CPTMutableLineStyle *googLineStyle = [googPlot.dataLineStyle mutableCopy];
googLineStyle.lineWidth = 1.0;
googLineStyle.lineColor = googColor;
googPlot.dataLineStyle = googLineStyle;
CPTMutableLineStyle *googSymbolLineStyle = [CPTMutableLineStyle lineStyle];
googSymbolLineStyle.lineColor = googColor;
CPTPlotSymbol *googSymbol = [CPTPlotSymbol starPlotSymbol];
googSymbol.fill = [CPTFill fillWithColor:googColor];
googSymbol.lineStyle = googSymbolLineStyle;
googSymbol.size = CGSizeMake(6.0f, 6.0f);
googPlot.plotSymbol = googSymbol;
}

我的问题是，我目前的方法是否正确尝试在图块空间上设置边界，还是我需要在同一个屏幕上绘制不同的图形并在图形上设置边界？如何在图块空间或图形上设置边界（以正确的方式为准！）？

谢谢！