Only one corner is getting rounded in UITextField

I am using the following code to make UITextField's Top corners rounded, but the problem is only left top corner is getting rounded. What I am doing wrong or is there any other way to do so.

- (void)roundCornersOnView:(UIView*)view onTopLeft:(BOOL)tl topRight:(BOOL)tr bottomLeft:(BOOL)bl bottomRight:(BOOL)br radius:(float)radius
{

    if (tl || tr || bl || br) {
        UIRectCorner corner = 0; //holds the corner
        //Determine which corner(s) should be changed
        if (tl) {
            corner = corner | UIRectCornerTopLeft;
        }
        if (tr) {
            corner = corner | UIRectCornerTopRight;
        }
        if (bl) {
            corner = corner | UIRectCornerBottomLeft;
        }
        if (br) {
            corner = corner | UIRectCornerBottomRight;
        }

        UIView* roundedView = view;
        UIBezierPath* maskPath = [UIBezierPath bezierPathWithRoundedRect:roundedView.bounds byRoundingCorners:corner cornerRadii:CGSizeMake(radius, radius)];
        CAShapeLayer* maskLayer = [CAShapeLayer layer];
        maskLayer.frame = roundedView.bounds;
        maskLayer.path = maskPath.CGPath;
        roundedView.layer.mask = maskLayer;
    }
}

Calling the above method

[self roundCornersOnView:textField onTopLeft:YES topRight:YES bottomLeft:NO bottomRight:NO radius:5.0];