Iphone 如何在核心图中只设置一条主线？

您好，我正在使用core plot创建一个图形，我想更改主线条和副线条的线条样式，线条样式已更改，但我们在core plot中有两条主线条顶部和底部线条如何删除顶部主线条

- (void) setupGraphAxis: (CPTXYGraph *) graph {
CPTColor *axisColor = [CPTColor colorWithComponentRed:255.0/255.0 green:255.0/255.0 blue:255.0/255.0 alpha:0.75];
CPTMutableLineStyle *axisLineStyle = [CPTMutableLineStyle lineStyle];
axisLineStyle.lineWidth = 1.5f;
axisLineStyle.lineColor = axisColor;


CPTMutableLineStyle *dashLineStyle = [CPTMutableLineStyle lineStyle];
dashLineStyle.lineColor = axisColor;
dashLineStyle.lineWidth = 1.5f;
dashLineStyle.dashPattern = [NSArray arrayWithObjects:[NSDecimalNumber numberWithInt:1],[NSDecimalNumber numberWithInt:2],nil];
dashLineStyle.patternPhase = 0.0f;

CPTMutableLineStyle *fullLineStyle = [CPTMutableLineStyle lineStyle];
fullLineStyle.lineColor = axisColor;
fullLineStyle.lineWidth = 1.5f;
//fullLineStyle.dashPattern = [NSArray arrayWithObjects:[NSDecimalNumber numberWithInt:1],nil];
fullLineStyle.lineCap = 0;
fullLineStyle.patternPhase = 0.0f;

//Configure x-axis
CPTXYAxisSet *axisSet = (CPTXYAxisSet *) graph.axisSet;

CPTXYAxis *x = axisSet.xAxis;
x.axisLineStyle = nil;
x.orthogonalCoordinateDecimal = CPTDecimalFromString(@"0");
x.minorTickLineStyle = nil;
x.majorTickLineStyle = nil;
CPTAxisLabelingPolicy policy = CPTAxisLabelingPolicyAutomatic;
x.labelingPolicy = policy;
x.labelTextStyle = nil;
x.preferredNumberOfMajorTicks = 1;


CPTXYAxis *y = axisSet.yAxis;
y.axisLineStyle = nil;
y.orthogonalCoordinateDecimal = CPTDecimalFromString(@"0");
y.minorTickLineStyle = nil;
y.majorTickLineStyle = nil;
y.majorGridLineStyle = fullLineStyle;
y.minorGridLineStyle = dashLineStyle;
y.labelingPolicy = policy;
y.preferredNumberOfMajorTicks = 1;
}

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您可以使用轴的

labelExclusionRanges

属性告诉它在创建记号、网格线和标签时跳过某些值。如果仍需要在该点上添加记号和/或标签，则可能需要添加另一个仅绘制网格线的不可见y轴，并让原始y轴绘制其他所有内容