如何使用Core Plot绘制直方图和折线图

Core Plot提供了散点图（CPScatterPlot)绘制，包括折线图和直方图，如下图所示：

下面的代码包括了折线图和直方图的实现： 1、.h文件： #import <UIKit/UIKit.h>#import <CorePlot/CorePlot.h>//散点图的数据点数：20#definenum 20@interfaceBarChartViewController : UIViewController <CPPlotDataSource>{ @private CPXYGraph *graph; double x[num] ;//散点的x坐标 double y1[num] ;//第1个散点图的y坐标 double y2[num];//第2个散点图的y坐标 } @end2、.m文件：#import "BarChartViewController.h"@implementation BarChartViewController-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation{ return YES;}#pragma mark -#pragma mark Initialization and teardown -(void)viewDidAppear:(BOOL)animated{ // 为CPGraph指定主题 graph = [[CPXYGraph alloc] initWithFrame:CGRectZero]; CPTheme *theme = [CPTheme themeNamed:kCPDarkGradientTheme]; [graph applyTheme:theme]; //把self.view由UIView转变为CPGraphHostingView，因为UIView无法加载CPGraph self.view=[[ CPGraphHostingView alloc ]initWithFrame :[ UIScreen mainScreen]. bounds ]; CPGraphHostingView*hostingView = (CPGraphHostingView *)self.view; [hostingView setHostedGraph :graph]; // CPGraph边框：无 graph.plotAreaFrame.borderLineStyle = nil; graph.plotAreaFrame.cornerRadius = 0.0f; //绘图空间 plotspace CPXYPlotSpace *plotSpace= (CPXYPlotSpace *)graph.defaultPlotSpace; //绘图空间大小：Y：0-300，x：0-16 plotSpace.yRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0.0f) length:CPDecimalFromFloat(200.0f)]; plotSpace.xRange = [CPPlotRange plotRangeWithLocation:CPDecimalFromFloat(0.0f) length:CPDecimalFromInt(num)]; // CPGraph四边不留白 graph.paddingLeft = 0.0f; graph.paddingRight = 0.0f; graph.paddingTop = 0.0f; graph.paddingBottom = 0.0f; //绘图区4边留白 graph.plotAreaFrame.paddingLeft = 45.0; graph.plotAreaFrame.paddingTop = 40.0; graph.plotAreaFrame.paddingRight = 5.0; graph.plotAreaFrame.paddingBottom = 80.0; //坐标系 CPXYAxisSet *axisSet =(CPXYAxisSet *)graph.axisSet; //x轴：为坐标系的x轴 CPXYAxis *X =axisSet.xAxis; //清除默认的轴标签,使用自定义的轴标签 X.labelingPolicy =CPAxisLabelingPolicyNone; //构造MutableArray，用于存放自定义的轴标签 NSMutableArray*customLabels = [NSMutableArray arrayWithCapacity:num]; //构造一个TextStyle static CPTextStyle*labelTextStyle=nil; labelTextStyle=[[CPTextStyle alloc]init]; labelTextStyle.color=[CPColor whiteColor]; labelTextStyle.fontSize=10.0f; //每个数据点一个轴标签 for (int i=0;i<num;i++) { CPAxisLabel *newLabel =[[CPAxisLabel alloc] initWithText: [NSString stringWithFormat:@"第%d个数据点",(i+1)] textStyle:labelTextStyle]; newLabel.tickLocation = CPDecimalFromInt(i); newLabel.offset = X.labelOffset + X.majorTickLength; newLabel.rotation = M_PI/2; [customLabelsaddObject:newLabel]; [newLabelrelease]; } X.axisLabels = [NSSet setWithArray:customLabels]; //y轴 CPXYAxis *y =axisSet.yAxis; //y轴：不显示小刻度线 y.minorTickLineStyle = nil; //大刻度线间距：50单位 y.majorIntervalLength = CPDecimalFromString(@"50"); //坐标原点：0 y.orthogonalCoordinateDecimal = CPDecimalFromString(@"0"); y.titleOffset = 45.0f; y.titleLocation = CPDecimalFromFloat(150.0f); // 第1个散点图：蓝色 CPScatterPlot*boundLinePlot = [[[CPScatterPlot alloc] init] autorelease]; //id，用于识别该散点图 boundLinePlot.identifier = @"BluePlot"; //线型设置 CPLineStyle* lineStyle= [[[CPLineStyle alloc]init] autorelease]; lineStyle.lineWidth = 1.0f; lineStyle.lineColor = [CPColor blueColor]; boundLinePlot.dataLineStyle =lineStyle; //设置数据源,必须实现CPPlotDataSource协议 boundLinePlot.dataSource = self; [graph addPlot:boundLinePlot]; // 在图形上添加一些小圆点符号（节点） CPLineStyle*symbolLineStyle = [[CPLineStyle alloc ]init]; //描边：黑色 symbolLineStyle.lineColor = [CPColor blackColor]; //符号类型：椭圆 CPPlotSymbol *plotSymbol= [CPPlotSymbol ellipsePlotSymbol]; //填充色：蓝色 plotSymbol.fill = [CPFill fillWithColor:[CPColor blueColor]]; //描边 plotSymbol.lineStyle =symbolLineStyle; //符号大小：10*10 plotSymbol.size = CGSizeMake(6.0, 6.0); //向图形上加入符号 boundLinePlot.plotSymbol =plotSymbol; // 创建渐变区 //渐变色1 CPColor *areaColor= [CPColor colorWithComponentRed:0.0 green:0.0 blue:1.0 alpha:1.0]; //创建一个颜色渐变：从 建变色1 渐变到 无色 CPGradient*areaGradient = [CPGradient gradientWithBeginningColor:areaColor endingColor:[CPColor clearColor]]; //渐变角度： -90度（顺时针旋转） areaGradient.angle = -90.0f; //创建一个颜色填充：以颜色渐变进行填充 CPFill*areaGradientFill = [CPFill fillWithGradient:areaGradient]; //为图形1设置渐变区 boundLinePlot.areaFill =areaGradientFill; //渐变区起始值，小于这个值的图形区域不再填充渐变色 boundLinePlot.areaBaseValue = CPDecimalFromString(@"0.0"); //interpolation值为CPScatterPlotInterpolation枚举类型，该枚举有3个值：//CPScatterPlotInterpolationLinear,线性插补——折线图.//CPScatterPlotInterpolationStepped,在后方进行插补——直方图//CPScatterPlotInterpolationHistogram,以散点为中心进行插补——直方图 boundLinePlot.interpolation = CPScatterPlotInterpolationHistogram; // 第2个散点图：绿色 CPScatterPlot*dataSourceLinePlot = [[[CPScatterPlot alloc] init] autorelease]; dataSourceLinePlot.identifier = @"GreenPlot"; //线型设置 lineStyle = [[[CPLineStyle alloc]init] autorelease]; lineStyle.lineWidth = 1.0f; lineStyle.lineColor = [CPColor greenColor]; dataSourceLinePlot.dataLineStyle =lineStyle; //设置数据源,必须实现CPPlotDataSource协议 dataSourceLinePlot.dataSource = self; [graph addPlot:dataSourceLinePlot]; //随机产生散点数据 NSUInteger i; for ( i = 0; i < num; i++ ) { x[i] = i ; y1[i] = (num*10)*(rand()/(float)RAND_MAX); y2[i] = (num*10)*(rand()/(float)RAND_MAX); } }#pragmamark -#pragmamark Plot Data Source Methods//返回散点数-(NSUInteger)numberOfRecordsForPlot:(CPPlot *)plot { return num ;}//根据参数返回数据（一个C数组）- (double*)doublesForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnumrecordIndexRange:(NSRange)indexRange { //返回类型：一个double指针（数组） double *values; NSString*identifier=(NSString*)[plot identifier]; switch (fieldEnum){ //如果请求的数据是散点x坐标,直接返回x坐标（两个图形是一样的），否则还要进一步判断是那个图形 case CPScatterPlotFieldX: values=x; break; case CPScatterPlotFieldY: //如果请求的数据是散点y坐标，则对于图形1，使用y1数组，对于图形2，使用y2数组 if([identifier isEqualToString:@"BluePlot"]) { values=y1; }else values=y2; break; } //数组指针右移个indexRage.location单位，则数组截去indexRage.location个元素 return values +indexRange.location ;}//添加数据标签-(CPLayer*)dataLabelForPlot:(CPPlot *)plot recordIndex:(NSUInteger)index{ //定义一个白色的TextStyle static CPTextStyle *whiteText= nil; if (!whiteText ) { whiteText= [[CPTextStyle alloc] init]; whiteText.color = [CPColor whiteColor]; } //定义一个TextLayer CPTextLayer *newLayer =nil; NSString*identifier=(NSString*)[plot identifier]; if([identifier isEqualToString:@"BluePlot"]) { newLayer= [[[CPTextLayer alloc] initWithText:[NSString stringWithFormat:@"%.0f", y1[index]] style:whiteText] autorelease]; } return newLayer;}@end