代码很简单，一看便知。这里为顺时针，若想要逆时针，clockwise改为0，还需更改起始角度和终点角度。

源码地址：

 

直接上代码：- (void)drawRect:(CGRect)rect {

CAShapeLayer *shapeLayer = [CAShapeLayer layer];    shapeLayer.frame = self.bounds;    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.frame.size.width/2, self.frame.size.height/2) radius:self.frame.size.height/2 startAngle:-M_PI_2 endAngle:M_PI*3/2 clockwise:1];    shapeLayer.path = path.CGPath;    shapeLayer.fillColor = [UIColor clearColor].CGColor;    shapeLayer.lineWidth = 10.0f;        if ([self.flag isEqualToString:@"track"]) {        shapeLayer.strokeColor = [UIColor colorWithRed:146/255.0f green:146/255.0f blue:146/255.0f alpha:1].CGColor;    } else{        shapeLayer.strokeColor = [UIColor colorWithRed:61/255.0f green:191/255.0f blue:135/255.0f alpha:1].CGColor;    }        //每个虚线长度为2，间隔为3   这句设置线条为虚线，去掉即为实线     shapeLayer.lineDashPattern = [NSArray arrayWithObjects:[NSNumber numberWithInt:2], [NSNumber numberWithInt:3], nil];    [self.layer addSublayer:shapeLayer];        if ([self.flag isEqualToString:@"process"]) {        CABasicAnimation *pathAnima = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];        pathAnima.duration = self.time;        pathAnima.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];        pathAnima.fromValue = [NSNumber numberWithFloat:0.0f];        pathAnima.toValue = [NSNumber numberWithFloat:1.0f];        pathAnima.fillMode = kCAFillModeForwards;        pathAnima.removedOnCompletion = NO;        [shapeLayer addAnimation:pathAnima forKey:@"strokeEndAnimation"];    }       } 随手截个图：