實線圓圈：
CAShapeLayer *solidLine = [CAShapeLayer layer];
CGMutablePathRef solidPath = CGPathCreateMutable();
solidLine.lineWidth = 1.0f ;
solidLine.strokeColor = [UIColor grayColor].CGColor;
solidLine.fillColor = [UIColor clearColor].CGColor;
CGPathAddEllipseInRect(solidPath, nil, CGRectMake(10, 25, 72, 72);
solidLine.path = solidPath;
CGPathRelease(solidPath);
[self.view.layer addSublayer:solidLine];
