iOS之画饼图

1.效果图如下

2.画饼图实现步骤如下：

• 1.在main.storyboard中拖入一个UIView控件，并设置其Custom Class 为HMPieView。如下图

  

• 2.新建HMPieView类

//
//  HMPieView.h
//  03-饼图
//

#import <UIKit/UIKit.h>

@interface HMPieView : UIView

@end

//
//  HMPieView.m
//  03-饼图
//

#import "HMPieView.h"
#import "UIColor+Random.h"
@implementation HMPieView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code

    NSArray *data = @[@25,@25,@50];

    // 1.获取上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    // 2.拼接路径
    CGPoint center = CGPointMake(125, 125);
    CGFloat radius = 120;
    CGFloat startA = 0;
    CGFloat angle = 0;
    CGFloat endA = 0;

    for (NSNumber *number in data) {
        // 2.拼接路径
        startA = endA;
        angle = number.intValue / 100.0 * M_PI * 2;
        endA = startA + angle;
        UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startA endAngle:endA clockwise:YES];
        [path addLineToPoint:center];

        [[UIColor randomColor] set];
        // 把路径添加上下文
        CGContextAddPath(ctx, path.CGPath);

        // 渲染
        CGContextFillPath(ctx);

    }

}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    CGFloat a = arc4random_uniform(6);
    //CGFloat a =  arc4random()%6;
    NSLog(@"随机数--%f",a);

    [self setNeedsDisplay];
}

- (void)drawPie
{
    // 1.获取上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    // 2.拼接路径
    CGPoint center = CGPointMake(125, 125);
    CGFloat radius = 120;
    CGFloat startA = 0;
    CGFloat angle = 0;
    CGFloat endA = 0;

    // 第一个扇形
    angle = 25 / 100.0 * M_PI * 2;
    endA = startA + angle;
    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startA endAngle:endA clockwise:YES];
    [path addLineToPoint:center];
    // 添加到上下文
    CGContextAddPath(ctx, path.CGPath);
    [[UIColor redColor] set];

    // 渲染
    CGContextFillPath(ctx);

    // 第二个扇形
    startA = endA;
    angle = 25 / 100.0 * M_PI * 2;
    endA = startA + angle;
    UIBezierPath *path1 = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startA endAngle:endA clockwise:YES];
    [path1 addLineToPoint:center];
    // 添加到上下文
    CGContextAddPath(ctx, path1.CGPath);
    [[UIColor greenColor] set];
    // 渲染
    CGContextFillPath(ctx);

    // 第三个扇形
    startA = endA;
    angle = 50 / 100.0 * M_PI * 2;
    endA = startA + angle;
    UIBezierPath *path2 = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startA endAngle:endA clockwise:YES];
    [path2 addLineToPoint:center];
    // 添加到上下文
    CGContextAddPath(ctx, path2.CGPath);
    [[UIColor blueColor] set];
    // 渲染
    CGContextFillPath(ctx);

   }

@end

• 3.新建UIColor+Random类

//
//  UIColor+Random.h
//  03-饼图
//

#import <UIKit/UIKit.h>

@interface UIColor (Random)
+ (UIColor *)randomColor;
@end

//
//  UIColor+Random.m
//  03-饼图
//

#import "UIColor+Random.h"

@implementation UIColor (Random)

+ (UIColor *)randomColor
{
    /*
     颜色有两种表现形式 RGB RGBA
     RGB 24
     R,G,B每个颜色通道8位
     8的二进制 255
     R,G,B每个颜色取值 0 ~255
     120 / 255.0

     */
    CGFloat r = arc4random_uniform(256) / 255.0;
    CGFloat g = arc4random_uniform(256) / 255.0;
    CGFloat b = arc4random_uniform(256) / 255.0;

    return [UIColor colorWithRed:r green:g blue:b alpha:1];
}

@end