圆角 path

    CGMutablePathRef path = CGPathCreateMutable();
    CGRect rect=CGRectInset(self.bounds, 10, 10);
    CGFloat minx = CGRectGetMinX(rect), midx = CGRectGetMidX(rect), maxx = CGRectGetMaxX(rect);
    CGFloat miny = CGRectGetMinY(rect), midy = CGRectGetMidY(rect), maxy = CGRectGetMaxY(rect);
    CGFloat radius=10.0;
    CGPathMoveToPoint(path, NULL, minx, midy);
    CGPathAddArcToPoint(path, NULL, minx, miny, midx, miny, radius);
    CGPathAddArcToPoint(path, NULL, maxx, miny, maxx, midy, radius);
    CGPathAddArcToPoint(path, NULL, maxx, maxy, midx, maxy, radius);
    CGPathAddArcToPoint(path, NULL, minx, maxy, minx, midy, radius);
    CGPathCloseSubpath(path);