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

}

 

@end

2、.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