我有以下代码使椭圆围绕其中心旋转。我希望能够将它定位UIImageView在某个位置（比如视图的中间）。
如果有人可以帮助我解决这个问题，我将不胜感激。
-(void)drawCircle
{
CGMutablePathRef circlePath = CGPathCreateMutable();
int radius = 400;
CGRect circleRect = CGRectMake(CENTER_Y-radius*0.7, CENTER_X-radius, 1.4*radius, 2*radius);
float midX = CGRectGetMidX(circleRect);
float midY = CGRectGetMidY(circleRect);
CGAffineTransform transform = CGAffineTransformMakeTranslation(-midX, -midY);
CGPathAddEllipseInRect( circlePath ,&transform , circleRect);
CAShapeLayer *circle = [[CAShapeLayer alloc] init];
circle.path = circlePath;
circle.opacity = 0.1;
circle.contentsScale = SCREEN_SCALE;
circle.fillColor = [UIColor blueColor].CGColor;
[aView.layer addSublayer:circle];
CABasicAnimation* theAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
theAnimation.fromValue = 0;
theAnimation.toValue = @(2*M_PI);
theAnimation.duration=3.5;
theAnimation.autoreverses=FALSE;
theAnimation.repeatCount=HUGE_VALF;
theAnimation.fillMode = kCAFillModeBoth;
theAnimation.removedOnCompletion=FALSE;
theAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
[circle addAnimation:theAnimation forKey:@"transform.rotation.z"];
}