//传入数据,饼状图

    pieChartView.dataArr = @[@20,@50,@80,@70,@40];

- (void)drawRect:(CGRect)rect {

    // Drawing code

#if 0

    //贝塞尔路径

    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(50, 50, 100, 100)];

    //Oval 椭圆

    //线条颜色

    [[UIColor redColor] setStroke];

    //线条宽度

    path.lineWidth = 5;

    //开始画

    [path stroke];

    //设置填充颜色

    [[UIColor yellowColor] set];

    //开始填充

    [path fill];

#endif

    //开始

    CGFloat startDegress = 0;

    //结束

    CGFloat endDegress = 0;

    for (int i = 0; i < _dataArr.count; i++) {

        //终点弧

        //计算数据每个元素的值所占的百分比

        endDegress += M_PI * 2 *([self.dataArr[i] floatValue]/[self sum]);

        //弧 路径

        UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.frame.size.width/2, self.frame.size.height/2) radius:MIN(self.frame.size.width, self.frame.size.height)/2 startAngle:startDegress endAngle:endDegress clockwise:YES];

        //更底层(这两句,相当于上面一句)

//        CGMutablePathRef path = CGPathCreateMutable();

//        CGPathAddArc(path, NULL,self.frame.size.width/2,self.frame.size.height/2, MIN(self.frame.size.width, self.frame.size.height)/2, startDegress, endDegress, YES);

        //重新修改开始的弧度

        //第二个弧的起点 ,是上一个弧的终点

        startDegress  = endDegress;

//注意:先画一个弧,然后终点-圆心 画一条线(以便能够填充,否则不能填充)

        //坐标为圆心

        [path addLineToPoint:CGPointMake(self.frame.size.width/2, self.frame.size.height/2)];

        //线条颜色

//        [[self randomColor] setStroke];

        //线条宽度

//        path.lineWidth = 5;

        //开始画

//        [path stroke];

        //设置填充颜色

        [[self randomColor] set];

        //开始填充

        [path fill];

    }

}

- (UIColor *)randomColor{

    return [UIColor colorWithRed:arc4random()%256/255.0 green:arc4random()%256/255.0 blue:arc4random()%256/255.0 alpha:1];

}

- (void)setDataArr:(NSArray *)dataArr{

    _dataArr = dataArr;

    //调用drawRect刷新(再走一次上面)

    [self setNeedsDisplay];

}

//获取数组中总数

#pragma mark -- 计算数组中 数据的总和

- (CGFloat)sum{

   __block CGFloat sum = 0;

    [self.dataArr enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

        sum = sum + [obj floatValue];

    }];

    return sum;

}

CoreGraphics--饼状图