一款不错的支持动画画圆的效果特效源码，该效果实现了动画画圆，还可以扩展成画其他平面图形功能等，大家可以下载看看吧。 
//定义所需要画的图形
-(void)intiUIOfView
{
UIBezierPath *path=[UIBezierPath bezierPath];
CGRect rect=[UIScreen mainScreen].applicationFrame;
[path addArcWithCenter:CGPointMake(rect.size.width/2,rect.size.height/2-20) radius:100 startAngle:0 endAngle:2*M_PI clockwise:NO];
arcLayer=[CAShapeLayer layer];
arcLayer.path=path.CGPath;//46,169,230
arcLayer.fillColor=[UIColor colorWithRed:46.0/255.0 green:169.0/255.0 blue:230.0/255.0 alpha:1].CGColor;
arcLayer.strokeColor=[UIColor colorWithWhite:1 alpha:0.7].CGColor;
arcLayer.lineWidth=3;
arcLayer.frame=self.view.frame;
[self.view.layer addSublayer:arcLayer];
[self drawLineAnimation:arcLayer];
}
//定义动画过程
-(void)drawLineAnimation:(CALayer*)layer
{
CABasicAnimation *bas=[CABasicAnimation animationWithKeyPath:@"strokeEnd"];
bas.duration=1;
bas.delegate=self;
bas.fromValue=[NSNumber numberWithInteger:0];
bas.toValue=[NSNumber numberWithInteger:1];
[layer addAnimation:bas forKey:@"key"];
}
源码下载：