(转)[IOS]如何动态画圆

转自：https://blog.csdn.net/dolacmeng/article/details/46291111

先放上我的代码：新建一个CircleView，继承UIView

#import "CircleView.h"

#define ScreenWidth [[UIScreen mainScreen] bounds].size.width
#define ScreenHeight [[UIScreen mainScreen] bounds].size.height
#define circle_btn_width ScreenWidth/6.3
#define circle_radius (ScreenWidth/2 - circle_btn_width + 10)

@interface CircleView()

@property (nonatomic) UIBezierPath *circle;
@property (nonatomic) CAShapeLayer *shapeLayer;
@property (nonatomic) NSTimer *timer;
@property (nonatomic) UIView *circleView;

@end

@implementation CircleView

- (instancetype)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        
        _circle = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, circle_radius*2, circle_radius*2)];
        CAShapeLayer *shape = [CAShapeLayer new];
        shape.frame = CGRectMake(0, 50, circle_radius*2, circle_radius*2);
        shape.position = self.center;
        shape.fillColor = [UIColor clearColor].CGColor;
        shape.lineWidth = 2.f;
        shape.strokeColor = [UIColor grayColor].CGColor;
        shape.strokeStart = 0.f;
        shape.strokeEnd = 1.f;
        shape.path = _circle.CGPath;
        [self.layer addSublayer:shape];
        
        _shapeLayer = [CAShapeLayer layer];
        _shapeLayer.frame = CGRectMake(0, 0, circle_radius*2, circle_radius*2);
        _shapeLayer.position = self.center;
        _shapeLayer.fillColor = [UIColor clearColor].CGColor;
        _shapeLayer.lineWidth = 2.f;
        _shapeLayer.strokeColor = [UIColor redColor].CGColor;
        _shapeLayer.strokeStart = 0.f;
        _shapeLayer.strokeEnd = 0.f;
        _shapeLayer.path = _circle.CGPath;
        [self.layer addSublayer:_shapeLayer];
        
        CGAffineTransform transform = CGAffineTransformIdentity;
        self.transform = CGAffineTransformRotate(transform, -M_PI/2);
        
        _timer = [NSTimer scheduledTimerWithTimeInterval:1.f target:self selector:@selector(animate) userInfo:nil repeats:YES];
    }
    
    return self;
}

-(void)animate{
    _shapeLayer.strokeEnd += 0.1;
}

调用：

CircleView *circleView = [[CircleView alloc]initWithFrame:CGRectMake(0, 0, circle_radius*2, circle_radius*2)];
circleView.center = self.view.center;
[self.view addSubview:circleView];

原理是下文：

UIBezierPath可以绘制矢量路径，而CAShapeLayer是Layer的子类，可以在屏幕进行绘制，本文主要思想是：CAShapeLayer按照UIBezierPath的矢量路径进行绘制。

效果图如图：

方法如下：

    @interface ViewController (){  
        CAShapeLayer *shapeLayer;  
        NSTimer *timer;  
    }  
      
    @end  
      
    @implementation ViewController  
      
    - (void)viewDidLoad {  
        [super viewDidLoad];  
          
        //第一步，通过UIBezierPath设置圆形的矢量路径  
        UIBezierPath *circle = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, 200, 200)];  
          
        //第二步，用CAShapeLayer沿着第一步的路径画一个完整的环（颜色灰色，起始点0，终结点1）  
        CAShapeLayer *bgLayer = [CAShapeLayer layer];  
        bgLayer.frame = CGRectMake(0, 0, 200, 200);//设置Frame  
        bgLayer.position = self.view.center;//居中显示  
        bgLayer.fillColor = [UIColor clearColor].CGColor;//填充颜色=透明色  
        bgLayer.lineWidth = 2.f;//线条大小  
        bgLayer.strokeColor = [UIColor grayColor].CGColor;//线条颜色  
        bgLayer.strokeStart = 0.f;//路径开始位置  
        bgLayer.strokeEnd = 1.f;//路径结束位置  
        bgLayer.path = circle.CGPath;//设置bgLayer的绘制路径为circle的路径  
        [self.view.layer addSublayer:bgLayer];//添加到屏幕上  
          
        //第三步，用CAShapeLayer沿着第一步的路径画一个红色的环形进度条，但是起始点=终结点=0，所以开始不可见  
        shapeLayer = [CAShapeLayer layer];  
        shapeLayer.frame = CGRectMake(0, 0, 200, 200);  
        shapeLayer.position = self.view.center;  
        shapeLayer.fillColor = [UIColor clearColor].CGColor;  
        shapeLayer.lineWidth = 2.f;  
        shapeLayer.strokeColor = [UIColor redColor].CGColor;  
        shapeLayer.strokeStart = 0;  
        shapeLayer.strokeEnd = 0;  
        shapeLayer.path = circle.CGPath;  
        [self.view.layer addSublayer:shapeLayer];  
          
        //第四步，用一个定时器进行测试，每一秒，进度加10%  
        timer = [NSTimer scheduledTimerWithTimeInterval:1.f target:self selector:@selector(animate) userInfo:nil repeats:YES];  
    }  
      
    -(void)animate{  
        shapeLayer.strokeEnd += 0.1;  
    }  

 我们可以对以上代码封装为一个CircleView，继承自View，封装后代码如下：

CircleView.h文件

    #import <UIKit/UIKit.h>  
      
    @interface CircleView : UIView  
      
    @property(assign,nonatomic)CGFloat startValue;  
    @property(assign,nonatomic)CGFloat lineWidth;  
    @property(assign,nonatomic)CGFloat value;  
    @property(strong,nonatomic)UIColor *lineColr;  
      
    @end  

CircleView.m文件:

 

    #import "CircleView.h"  
      
    @interface CircleView()  
    @property(strong,nonatomic)UIBezierPath *path;  
    @property(strong,nonatomic)CAShapeLayer *shapeLayer;  
    @property(strong,nonatomic)CAShapeLayer *bgLayer;  
      
    @end  
      
    @implementation CircleView  
      
      
    - (instancetype)initWithFrame:(CGRect)frame  
    {  
        self = [super initWithFrame:frame];  
        if (self) {  
            _path = [UIBezierPath bezierPathWithOvalInRect:self.bounds];  
              
            _bgLayer = [CAShapeLayer layer];  
            _bgLayer.frame = self.bounds;  
            _bgLayer.fillColor = [UIColor clearColor].CGColor;  
            _bgLayer.lineWidth = 2.f;  
            _bgLayer.strokeColor = [UIColor grayColor].CGColor;  
            _bgLayer.strokeStart = 0.f;  
            _bgLayer.strokeEnd = 1.f;  
            _bgLayer.path = _path.CGPath;  
            [self.layer addSublayer:_bgLayer];  
              
            _shapeLayer = [CAShapeLayer layer];  
            _shapeLayer.frame = self.bounds;  
            _shapeLayer.fillColor = [UIColor clearColor].CGColor;  
            _shapeLayer.lineWidth = 2.f;  
            _shapeLayer.lineCap = kCALineCapRound;  
            _shapeLayer.strokeColor = [UIColor redColor].CGColor;  
            _shapeLayer.strokeStart = 0.f;  
            _shapeLayer.strokeEnd = 0.f;  
              
              
            _shapeLayer.path = _path.CGPath;  
            [self.layer addSublayer:_shapeLayer];  
             
        }  
        return self;  
    }  
      
    @synthesize value = _value;  
    -(void)setValue:(CGFloat)value{  
        _value = value;  
        _shapeLayer.strokeEnd = value;  
    }  
    -(CGFloat)value{  
        return _value;  
    }  
      
    @synthesize lineColr = _lineColr;  
    -(void)setLineColr:(UIColor *)lineColr{  
        _lineColr = lineColr;  
        _shapeLayer.strokeColor = lineColr.CGColor;  
    }  
    -(UIColor*)lineColr{  
        return _lineColr;  
    }  
      
    @synthesize lineWidth = _lineWidth;  
    -(void)setLineWidth:(CGFloat)lineWidth{  
        _lineWidth = lineWidth;  
        _shapeLayer.lineWidth = lineWidth;  
        _bgLayer.lineWidth = lineWidth;  
    }  
    -(CGFloat)lineWidth{  
        return _lineWidth;  
    }  
      
    @end  

在需要使用的ViewContrller中使用以下代码调用即可:

    CircleView *view = [[CircleView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];  
       [self.view addSubview:view];  
       view.center = self.view.center;  
       [view setLineWidth:6.f];  
       [view setLineColr:[UIColor redColor]];  

 另外默认的坐标如下图（图来自http://justsee.iteye.com/blog/1972853）

 

有时候我们需要开始点在顶部，即（3/2）π 处，其中一个思路是将整个View逆时针旋转90度即可，在CircleView.m的initWithFrame中添加以下代码即可：

CGAffineTransform transform = CGAffineTransformIdentity;  
self.transform = CGAffineTransformRotate(transform, -M_PI / 2);

 注意：变型只能对UIView使用，对CAShapeLayer没有效果

 

参考：

1.iOS开发贝塞尔曲线UIBezierPath（后记）

https://www.cnblogs.com/ioshe/p/5481841.html