iOS:使用贝塞尔曲线绘制图表（折线图、柱状图、饼状图）

1.介绍：

UIBezierPath ：画贝塞尔曲线的path类

UIBezierPath定义 ： 贝赛尔曲线的每一个顶点都有两个控制点，用于控制在该顶点两侧的曲线的弧度。

曲线的定义有四个点：起始点、终止点（也称锚点）以及两个相互分离的中间点。

滑动两个中间点，贝塞尔曲线的形状会发生变化。

UIBezierPath ：对象是CGPathRef数据类型的封装，可以方便的让我们画出 矩形 、 椭圆 或者 直线和曲线的组合形状

初始化方法：

+ (instancetype)bezierPath;

//创建一个矩形

+ (instancetype)bezierPathWithRect:(CGRect)rect;

//创建圆形或者椭圆形

+ (instancetype)bezierPathWithOvalInRect:(CGRect)rect;

+ (instancetype)bezierPathWithRoundedRect:(CGRect)rect cornerRadius:(CGFloat)cornerRadius; // rounds all corners with the same horizontal and vertical radius

+ (instancetype)bezierPathWithRoundedRect:(CGRect)rect byRoundingCorners:(UIRectCorner)corners cornerRadii:(CGSize)cornerRadii;

+ (instancetype)bezierPathWithArcCenter:(CGPoint)center radius:(CGFloat)radius startAngle:(CGFloat)startAngle endAngle:(CGFloat)endAngle clockwise:(BOOL)clockwise;

+ (instancetype)bezierPathWithCGPath:(CGPathRef)CGPath;

2.最基本的使用方法是：

//设置描绘的起点

- (void)moveToPoint:(CGPoint)point;

//画直线

- (void)addLineToPoint:(CGPoint)point;

//画曲线

(1)绘制二次贝塞尔曲线   分别对应终点和一个控制点

- (void)addQuadCurveToPoint:(CGPoint)endPoint controlPoint:(CGPoint)controlPoint

(1)绘制三次贝塞尔曲线   分别对应终点和两个控制点

- (void)addCurveToPoint:(CGPoint)endPoint controlPoint1:(CGPoint)controlPoint1 controlPoint2:(CGPoint)controlPoint2;

//画圆弧

- (void)addArcWithCenter:(CGPoint)center radius:(CGFloat)radius startAngle:(CGFloat)startAngle endAngle:(CGFloat)endAngle clockwise:(BOOL)clockwise

3.使用贝塞尔曲线的基本步骤是：

(1）创建一个Bezier path对象。

（2）使用方法moveToPoint:去设置初始线段的起点。

（3）添加line或者curve去定义一个或者多个subpaths。

（4）改变UIBezierPath对象跟绘图相关的属性。

4.demo演示如下：

创建一个工具类，BezierCurveView，同时给它创建一个xib文件，它继承自UIView，用来专门绘制图表的画布

BezierCurveView.h

//
//  BezierCurveView.h
//  BezierCurveLineDemo
//
//  Created by mac on 16/7/20.
//  Copyright © 2016年 xiayuanquan. All rights reserved.
//

#import <UIKit/UIKit.h>

#define MARGIN            30   // 坐标轴与画布间距
#define Y_EVERY_MARGIN    20   // y轴每一个值的间隔数

// 颜色RGB
#define XYQColor(r, g, b) [UIColor colorWithRed:(r)/255.0 green:(g)/255.0 blue:(b)/255.0 alpha:1.0]
#define XYQColorRGBA(r, g, b, a) [UIColor colorWithRed:(r)/255.0 green:(g)/255.0 blue:(b)/255.0 alpha:a]

// 随机色
#define XYQRandomColor  XYQColor(arc4random_uniform(256), arc4random_uniform(256), arc4random_uniform(256))

// 线条类型
typedef NS_ENUM(NSInteger, LineType) {
    LineType_Straight, // 折线
    LineType_Curve     // 曲线
};

@interface BezierCurveView : UIView

//初始化画布
+(instancetype)initWithFrame:(CGRect)frame;

/**
 *  画折线图
 *  @param x_names      x轴值的所有值名称
 *  @param targetValues 所有目标值
 *  @param lineType     直线类型
 */
-(void)drawLineChartViewWithX_Value_Names:(NSMutableArray *)x_names TargetValues:(NSMutableArray *)targetValues LineType:(LineType) lineType;

/**
 *  画柱状图
 *  @param x_names      x轴值的所有值名称
 *  @param targetValues 所有目标值
 */
-(void)drawBarChartViewWithX_Value_Names:(NSMutableArray *)x_names TargetValues:(NSMutableArray *)targetValues;

/**
 *  画饼状图
 *  @param x_names      x轴值的所有值名称
 *  @param targetValues 所有目标值
 */
-(void)drawPieChartViewWithX_Value_Names:(NSMutableArray *)x_names TargetValues:(NSMutableArray *)targetValues;

@end

BezierCurveView.m

//
//  BezierCurveView.m
//  BezierCurveLineDemo
//
//  Created by mac on 16/7/20.
//  Copyright © 2016年 xiayuanquan. All rights reserved.
//

#import "BezierCurveView.h"

static CGRect myFrame;

@interface BezierCurveView ()

@end

@implementation BezierCurveView

//初始化画布
+(instancetype)initWithFrame:(CGRect)frame{

    BezierCurveView *bezierCurveView = [[NSBundle mainBundle] loadNibNamed:@"BezierCurveView" owner:self options:nil].lastObject;
    bezierCurveView.frame = frame;

    //背景视图
    UIView *backView = [[UIView alloc] initWithFrame:CGRectMake(, , frame.size.width, frame.size.height)];
    backView.backgroundColor = XYQColor(, , );
    [bezierCurveView addSubview:backView];

    myFrame = frame;
    return bezierCurveView;
}

/**
 *  画坐标轴
 */
-(void)drawXYLine:(NSMutableArray *)x_names{

    UIBezierPath *path = [UIBezierPath bezierPath];

    //1.Y轴、X轴的直线
    [path moveToPoint:CGPointMake(MARGIN, CGRectGetHeight(myFrame)-MARGIN)];
    [path addLineToPoint:CGPointMake(MARGIN, MARGIN)];

    [path moveToPoint:CGPointMake(MARGIN, CGRectGetHeight(myFrame)-MARGIN)];
    [path addLineToPoint:CGPointMake(MARGIN+CGRectGetWidth(myFrame)-*MARGIN, CGRectGetHeight(myFrame)-MARGIN)];

    //2.添加箭头
    [path moveToPoint:CGPointMake(MARGIN, MARGIN)];
    [path addLineToPoint:CGPointMake(MARGIN-, MARGIN+)];
    [path moveToPoint:CGPointMake(MARGIN, MARGIN)];
    [path addLineToPoint:CGPointMake(MARGIN+, MARGIN+)];

    [path moveToPoint:CGPointMake(MARGIN+CGRectGetWidth(myFrame)-*MARGIN, CGRectGetHeight(myFrame)-MARGIN)];
    [path addLineToPoint:CGPointMake(MARGIN+CGRectGetWidth(myFrame)-*MARGIN-, CGRectGetHeight(myFrame)-MARGIN-)];
    [path moveToPoint:CGPointMake(MARGIN+CGRectGetWidth(myFrame)-*MARGIN, CGRectGetHeight(myFrame)-MARGIN)];
    [path addLineToPoint:CGPointMake(MARGIN+CGRectGetWidth(myFrame)-*MARGIN-, CGRectGetHeight(myFrame)-MARGIN+)];

    //3.添加索引格
    //X轴
    for (int i=; i<x_names.count; i++) {
        CGFloat X = MARGIN + MARGIN*(i+);
        CGPoint point = CGPointMake(X,CGRectGetHeight(myFrame)-MARGIN);
        [path moveToPoint:point];
        [path addLineToPoint:CGPointMake(point.x, point.y-)];
    }
    //Y轴（实际长度为200,此处比例缩小一倍使用）
    for (int i=; i<; i++) {
        CGFloat Y = CGRectGetHeight(myFrame)-MARGIN-Y_EVERY_MARGIN*i;
        CGPoint point = CGPointMake(MARGIN,Y);
        [path moveToPoint:point];
        [path addLineToPoint:CGPointMake(point.x+, point.y)];
    }

    //4.添加索引格文字
    //X轴
    for (int i=; i<x_names.count; i++) {
        CGFloat X = MARGIN +  + MARGIN*i;
        UILabel *textLabel = [[UILabel alloc] initWithFrame:CGRectMake(X, CGRectGetHeight(myFrame)-MARGIN, MARGIN, )];
        textLabel.text = x_names[i];
        textLabel.font = [UIFont systemFontOfSize:];
        textLabel.textAlignment = NSTextAlignmentCenter;
        textLabel.textColor = [UIColor blueColor];
        [self addSubview:textLabel];
    }
    //Y轴
    for (int i=; i<; i++) {
        CGFloat Y = CGRectGetHeight(myFrame)-MARGIN-Y_EVERY_MARGIN*i;
        UILabel *textLabel = [[UILabel alloc] initWithFrame:CGRectMake(, Y-, MARGIN, )];
        textLabel.text = [NSString stringWithFormat:@"%d",*i];
        textLabel.font = [UIFont systemFontOfSize:];
        textLabel.textAlignment = NSTextAlignmentCenter;
        textLabel.textColor = [UIColor redColor];
        [self addSubview:textLabel];
    }

    //5.渲染路径
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.path = path.CGPath;
    shapeLayer.strokeColor = [UIColor blackColor].CGColor;
    shapeLayer.fillColor = [UIColor clearColor].CGColor;
    shapeLayer.borderWidth = 2.0;
    [self.subviews[].layer addSublayer:shapeLayer];
}

/**
 *  画折线图
 */
-(void)drawLineChartViewWithX_Value_Names:(NSMutableArray *)x_names TargetValues:(NSMutableArray *)targetValues LineType:(LineType) lineType{

    //1.画坐标轴
    [self drawXYLine:x_names];

    //2.获取目标值点坐标
    NSMutableArray *allPoints = [NSMutableArray array];
    for (int i=; i<targetValues.count; i++) {
        CGFloat doubleValue = *[targetValues[i] floatValue]; //目标值放大两倍
        CGFloat X = MARGIN + MARGIN*(i+);
        CGFloat Y = CGRectGetHeight(myFrame)-MARGIN-doubleValue;
        CGPoint point = CGPointMake(X,Y);
        UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(point.x-, point.y-, 2.5, 2.5) cornerRadius:2.5];
        CAShapeLayer *layer = [CAShapeLayer layer];
        layer.strokeColor = [UIColor purpleColor].CGColor;
        layer.fillColor = [UIColor purpleColor].CGColor;
        layer.path = path.CGPath;
        [self.subviews[].layer addSublayer:layer];
        [allPoints addObject:[NSValue valueWithCGPoint:point]];
    }

    //3.坐标连线
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:[allPoints[] CGPointValue]];
    CGPoint PrePonit;
    switch (lineType) {
        case LineType_Straight: //直线
            for (int i =; i<allPoints.count; i++) {
                CGPoint point = [allPoints[i] CGPointValue];
                [path addLineToPoint:point];
            }
            break;
        case LineType_Curve:   //曲线
            for (int i =; i<allPoints.count; i++) {
                if (i==) {
                    PrePonit = [allPoints[] CGPointValue];
                }else{
                    CGPoint NowPoint = [allPoints[i] CGPointValue];
                    [path addCurveToPoint:NowPoint controlPoint1:CGPointMake((PrePonit.x+NowPoint.x)/, PrePonit.y) controlPoint2:CGPointMake((PrePonit.x+NowPoint.x)/, NowPoint.y)]; //三次曲线
                    PrePonit = NowPoint;
                }
            }
            break;
    }
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.path = path.CGPath;
    shapeLayer.strokeColor = [UIColor greenColor].CGColor;
    shapeLayer.fillColor = [UIColor clearColor].CGColor;
    shapeLayer.borderWidth = 2.0;
    [self.subviews[].layer addSublayer:shapeLayer];

    //4.添加目标值文字
    for (int i =; i<allPoints.count; i++) {
        UILabel *label = [[UILabel alloc] init];
        label.textColor = [UIColor purpleColor];
        label.textAlignment = NSTextAlignmentCenter;
        label.font = [UIFont systemFontOfSize:];
        [self.subviews[] addSubview:label];

        if (i==) {
            CGPoint NowPoint = [allPoints[] CGPointValue];
            label.text = [NSString stringWithFormat:@"%.0lf",(CGRectGetHeight(myFrame)-NowPoint.y-MARGIN)/];
            label.frame = CGRectMake(NowPoint.x-MARGIN/, NowPoint.y-, MARGIN, );
            PrePonit = NowPoint;
        }else{
            CGPoint NowPoint = [allPoints[i] CGPointValue];
            if (NowPoint.y<PrePonit.y) {  //文字置于点上方
                label.frame = CGRectMake(NowPoint.x-MARGIN/, NowPoint.y-, MARGIN, );
            }else{ //文字置于点下方
                label.frame = CGRectMake(NowPoint.x-MARGIN/, NowPoint.y, MARGIN, );
            }
            label.text = [NSString stringWithFormat:@"%.0lf",(CGRectGetHeight(myFrame)-NowPoint.y-MARGIN)/];
            PrePonit = NowPoint;
        }
    }
}

/**
 *  画柱状图
 */
-(void)drawBarChartViewWithX_Value_Names:(NSMutableArray *)x_names TargetValues:(NSMutableArray *)targetValues{

    //1.画坐标轴
    [self drawXYLine:x_names];

    //2.每一个目标值点坐标
    for (int i=; i<targetValues.count; i++) {
        CGFloat doubleValue = *[targetValues[i] floatValue]; //目标值放大两倍
        CGFloat X = MARGIN + MARGIN*(i+)+;
        CGFloat Y = CGRectGetHeight(myFrame)-MARGIN-doubleValue;
        UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(X-MARGIN/, Y, MARGIN-, doubleValue)];
        CAShapeLayer *shapeLayer = [CAShapeLayer layer];
        shapeLayer.path = path.CGPath;
        shapeLayer.strokeColor = [UIColor clearColor].CGColor;
        shapeLayer.fillColor = XYQRandomColor.CGColor;
        shapeLayer.borderWidth = 2.0;
        [self.subviews[].layer addSublayer:shapeLayer];

        //3.添加文字
        UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(X-MARGIN/, Y-, MARGIN-, )];
        label.text = [NSString stringWithFormat:@"%.0lf",(CGRectGetHeight(myFrame)-Y-MARGIN)/];
        label.textColor = [UIColor purpleColor];
        label.textAlignment = NSTextAlignmentCenter;
        label.font = [UIFont systemFontOfSize:];
        [self.subviews[] addSubview:label];
    }
}

/**
 *  画饼状图
 */
-(void)drawPieChartViewWithX_Value_Names:(NSMutableArray *)x_names TargetValues:(NSMutableArray *)targetValues{

    //设置圆点
    CGPoint point = CGPointMake(self.frame.size.width/,self.frame.size.height/);
    CGFloat startAngle = ;
    CGFloat endAngle ;
    CGFloat radius = ;

    //计算总数
    __block CGFloat allValue = ;
    [targetValues enumerateObjectsUsingBlock:^(NSNumber *targetNumber, NSUInteger idx, BOOL * _Nonnull stop) {
        allValue += [targetNumber floatValue];
    }];

    //画图
    for (int i =; i<targetValues.count; i++) {

        CGFloat targetValue = [targetValues[i] floatValue];
        endAngle = startAngle + targetValue/allValue**M_PI;

        //bezierPath形成闭合的扇形路径
        UIBezierPath *bezierPath = [UIBezierPath bezierPathWithArcCenter:point
                                                                   radius:radius
                                                               startAngle:startAngle                                                                 endAngle:endAngle
                                                                clockwise:YES];
        [bezierPath addLineToPoint:point];
        [bezierPath closePath];

        //添加文字
        CGFloat X = point.x + *cos(startAngle+(endAngle-startAngle)/) - ;
        CGFloat Y = point.y + *sin(startAngle+(endAngle-startAngle)/) - ;
        UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(X, Y, , )];
        label.text = x_names[i];
        label.font = [UIFont systemFontOfSize:];
        label.textColor = XYQColor(, , );
        [self.subviews[] addSubview:label];

        //渲染
        CAShapeLayer *shapeLayer=[CAShapeLayer layer];
        shapeLayer.lineWidth = ;
        shapeLayer.fillColor = XYQRandomColor.CGColor;
        shapeLayer.path = bezierPath.CGPath;
        [self.layer addSublayer:shapeLayer];

        startAngle = endAngle;
    }
}
@end

在ViewController.m文件中测试如下：

//
//  ViewController.m
//  BezierCurveLineDemo
//
//  Created by mac on 16/7/22.
//  Copyright © 2016年 xiayuanquan. All rights reserved.
//

#import "ViewController.h"
#import "BezierCurveView.h"

#define SCREEN_W  [UIScreen mainScreen].bounds.size.width
#define SCREEN_H  [UIScreen mainScreen].bounds.size.height

@interface ViewController ()
@property (strong,nonatomic)BezierCurveView *bezierView;
@property (strong,nonatomic)NSMutableArray *x_names;
@property (strong,nonatomic)NSMutableArray *targets;
@end

@implementation ViewController

/**
 *  X轴值
 */
-(NSMutableArray *)x_names{
    if (!_x_names) {
        _x_names = [NSMutableArray arrayWithArray:@[@"语文",@"数学",@"英语",@"物理",@"化学",@"生物",@"政治",@"历史",@"地理"]];
    }
    return _x_names;
}
/**
 *  Y轴值
 */
-(NSMutableArray *)targets{
    if (!_targets) {
        _targets = [NSMutableArray arrayWithArray:@[@,@,@,@,@,@,@,@,@]];
    }
    return _targets;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    //1.初始化
    _bezierView = [BezierCurveView initWithFrame:CGRectMake(, , SCREEN_W-, )];
    _bezierView.center = self.view.center;
    [self.view addSubview:_bezierView];

    //2.折线图
    [self drawLineChart];

    //3.柱状图
    //    [self drawBaseChart];

    //4.饼状图
    //    [self drawPieChart];

}

//画折线图
-(void)drawLineChart{

    //直线
    //    [_bezierView drawLineChartViewWithX_Value_Names:self.x_names TargetValues:self.targets LineType:LineType_Straight];

    //曲线
    [_bezierView drawLineChartViewWithX_Value_Names:self.x_names TargetValues:self.targets LineType:LineType_Curve];
}

//画柱状图
-(void)drawBaseChart{
    [_bezierView drawBarChartViewWithX_Value_Names:self.x_names TargetValues:self.targets];
}

//画饼状图
-(void)drawPieChart{
    [_bezierView drawPieChartViewWithX_Value_Names:self.x_names TargetValues:self.targets];
}
@end

演示截图如下：

 

 

下载地址：

Github：https://github.com/xiayuanquan/BezierCurveLineTest