实例：

@interface QACircleProgressView : UIView{
    CAShapeLayer *_trackLayer;
    UIBezierPath *_trackPath;
    CAShapeLayer *_progressLayer;
    UIBezierPath *_progressPath;
}

@property (nonatomic, strong) UIColor *trackColor;
@property (nonatomic, strong) UIColor *progressColor;
@property (nonatomic) float progress;//0~1之间的数
@property (nonatomic) float progressWidth;

- (void)setProgress:(float)progress animated:(BOOL)animated;

@end

import "QACircleProgressView.h"

@implementation QACircleProgressView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        
        // Initialization code
        _trackLayer = [CAShapeLayer new];
        _trackLayer.fillColor = nil;
        _trackLayer.frame = self.bounds;
        [self.layer addSublayer:_trackLayer];
        
        _progressLayer = [CAShapeLayer new];
        [self.layer addSublayer:_progressLayer];
        _progressLayer.fillColor = nil;
        _progressLayer.lineCap = kCALineCapRound;
        _progressLayer.frame = self.bounds;
        
        //默认5
        self.progressWidth = 5;
    }
    return self;
}

- (void)setTrack
{
 
    //bezierPathWithOvalInRect
    _trackPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(CGRectGetWidth(self.bounds) / 2, CGRectGetHeight(self.bounds) / 2) radius:(self.bounds.size.width)/ 2 startAngle:0 endAngle:M_PI * 2 clockwise:YES];;
    _trackLayer.path = _trackPath.CGPath;
}

- (void)setProgress
{
    _progressPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(CGRectGetWidth(self.bounds) / 2, CGRectGetHeight(self.bounds) / 2) radius:self.bounds.size.width/ 2 startAngle:- M_PI_2 endAngle:(M_PI * 2) * _progress - M_PI_2 clockwise:YES];
    _progressLayer.path = _progressPath.CGPath;
}




//设置进度条的宽度
- (void)setProgressWidth:(float)progressWidth
{
    _progressWidth = progressWidth;
    _trackLayer.lineWidth = _progressWidth;
    _progressLayer.lineWidth = _progressWidth;
    
    [self setTrack];
    [self setProgress];
}

- (void)setTrackColor:(UIColor *)trackColor
{
    _trackLayer.strokeColor = trackColor.CGColor;
}

- (void)setProgressColor:(UIColor *)progressColor
{
    _progressLayer.strokeColor = progressColor.CGColor;
}

//设置进度
- (void)setProgress:(float)progress
{
    _progress = progress;
    
    [self setProgress];
}

- (void)setProgress:(float)progress animated:(BOOL)animated
{
    [self setProgress:progress];
    // 给这个layer添加动画效果

    CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];

    pathAnimation.duration = 0.8;

    pathAnimation.fromValue = [NSNumber numberWithFloat:0.0f];

    pathAnimation.toValue = [NSNumber numberWithFloat:1.0f];

    [_progressLayer addAnimation:pathAnimation forKey:nil];

}

@end

ViewController:

/*  使用CAShapeLayer 结合 UIBezierPath 画出想要的图形
 *  1，新建UIBezierPath 对象
 *  2，新建CAShapeLayer 对象 
 *  3,bezierPath 对象的CGPath 赋值给caShapeLayer.path
 *  4,把caShapeLayer添加到某个图形的layer中
 */
- (void)viewDidLoad {
    [super viewDidLoad];
  
    QACircleProgressView *progressView = [[QACircleProgressView alloc]initWithFrame:CGRectMake(20,50, 80, 80)];
     [self.view addSubview:progressView];
    progressView.progressWidth = 3;
    progressView.progressColor = [UIColor colorWithRed:136/255.0 green:199/255.0 blue:80/255.0 alpha:1.0];
    progressView.trackColor = [UIColor colorWithRed:223/255.0 green:223/255.0 blue:223/255.0 alpha:1.0];
    progressView.progress = 0.8;
}

附：效果进度条动画。