x轴标签与核心图中的图基础之间的未知大间距

Question

我有core-plot的基本散点图，y轴似乎正常工作。似乎为了获得一个x轴标签，我必须添加很多paddingBottom，这也使我的情节得到了大约三分之一。当我的填充不是250（应该更像是50）时，我的x轴标签不在哪里。它就消失了。

#define X_MIN           (0)
#define X_MAX           (1000)
#define X_INTERVAL      (250)
#define X_TITLE_OFFSET  (30)
#define X_TITLE_PADDING (250)

#define Y_MIN           (9000)
#define Y_MAX           (13000)
#define Y_INTERVAL      (500)
#define Y_TITLE_OFFSET  (50)
#define Y_TITLE_PADDING (50)

- (void)viewDidLoad {
  NSLog(@"viewDidLoad");

  plotXMinRange = X_MIN;
  plotXMaxRange = X_MAX;
  plotXInterval = X_INTERVAL;
  plotYMinRange = Y_MIN;
  plotYMaxRange = Y_MAX;
  plotYInterval = Y_INTERVAL;

  [self initLinePlot];
}

-(void)initLinePlot {
  // Initialize and display Graph (x and y axis lines)
  self.graph = [[CPTXYGraph alloc] initWithFrame:self.graphView.bounds];
  self.hostView = [[CPTGraphHostingView alloc] initWithFrame:self.graphView.bounds];
  self.hostView.hostedGraph = self.graph;
  [self.graphView addSubview:hostView];

  // Apply styling to Graph
  [self.graph applyTheme:[CPTTheme themeNamed:kCPTPlainWhiteTheme]];

  // Set graph backgound area transparent
  self.graph.backgroundColor = nil;
  self.graph.fill = nil;
  self.graph.plotAreaFrame.fill = nil;
  self.graph.plotAreaFrame.plotArea.fill = nil;

  // Remove top and right lines of graph
  self.graph.plotAreaFrame.borderLineStyle = nil;
  self.graph.plotAreaFrame.masksToBorder = NO;

  // Configure graph paddding
  self.graph.paddingBottom = X_TITLE_PADDING;
  self.graph.paddingLeft = Y_TITLE_PADDING;
  self.graph.paddingRight = 0;
  self.graph.paddingTop = 0;

  // Configure x and y axis range
  CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)self.graph.defaultPlotSpace;
  plotSpace.allowsUserInteraction = NO;
  plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromInt(plotXMinRange)
                                                  length:CPTDecimalFromInt(plotXMaxRange - plotXMinRange)];
  plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromInt(plotYMinRange)
                                                  length:CPTDecimalFromInt(plotYMaxRange - plotYMinRange)];

  CPTXYAxisSet *axisSet = (CPTXYAxisSet *)self.graph.axisSet;

  NSNumberFormatter *axisLabelFormatter = [[NSNumberFormatter alloc] init];
  [axisLabelFormatter setGeneratesDecimalNumbers:NO];
  [axisLabelFormatter setNumberStyle:NSNumberFormatterDecimalStyle];

  // Configure x-axis properties
  axisSet.xAxis.majorIntervalLength = CPTDecimalFromInt(plotXInterval);
  axisSet.xAxis.minorTicksPerInterval = 4;
  axisSet.xAxis.minorTickLength = 5;
  axisSet.xAxis.majorTickLength = 7;
  axisSet.xAxis.title = @"Time [s]";
  axisSet.xAxis.titleOffset = X_TITLE_OFFSET;
  axisSet.xAxis.labelFormatter = axisLabelFormatter;

  // Configure y-axis properties
  axisSet.yAxis.majorIntervalLength = CPTDecimalFromInt(plotYInterval);
  axisSet.yAxis.minorTicksPerInterval = 4;
  axisSet.yAxis.minorTickLength = 5;
  axisSet.yAxis.majorTickLength = 7;
  axisSet.yAxis.title = @"Total Volume [mL]";
  axisSet.yAxis.titleOffset = Y_TITLE_OFFSET;
  axisSet.yAxis.labelFormatter = axisLabelFormatter;

  // Configure line plot and set line properties
  self.linePlot = [[CPTScatterPlot alloc] init];
  self.linePlot.dataSource = self;
  [self.graph addPlot:self.linePlot toPlotSpace:plotSpace];

  // Configure line plot style
  CPTMutableLineStyle *lineStyle = [self.linePlot.dataLineStyle mutableCopy];
  lineStyle.lineWidth = 2;
  lineStyle.lineColor = [CPTColor blackColor];
  self.linePlot.dataLineStyle = lineStyle;

  CPTMutableLineStyle *symbolineStyle = [CPTMutableLineStyle lineStyle];
  symbolineStyle.lineColor = [CPTColor blackColor];
  CPTPlotSymbol *symbol = [CPTPlotSymbol ellipsePlotSymbol];
  symbol.fill = [CPTFill fillWithColor:[CPTColor blackColor]];
  symbol.lineStyle = symbolineStyle;
  symbol.size = CGSizeMake(3.0f, 3.0f);
  self.linePlot.plotSymbol = symbol;

  // Configure graph grid line styles
  CPTMutableLineStyle *gridLineStyle = [[CPTMutableLineStyle alloc] init];
  gridLineStyle.lineColor = [CPTColor grayColor];
  gridLineStyle.lineWidth = 0.5;
  axisSet.xAxis.majorGridLineStyle = gridLineStyle;
  axisSet.yAxis.majorGridLineStyle = gridLineStyle;
}

Answer 1

默认情况下，轴始终在（0,0）处交叉，这远低于yRange（9,000）的起始位置。大底部填充向上推动图形，以便y = 0是可见的，尽管图形下方有大的空白空间。您有几种选择：

1. 使用axisConstraints将轴锁定到某个位置（例如，绘图区域的下边缘）。

2. 将x轴的orthogonalPosition更新为plotYMinRange。