animate view drawn with UIBezierPath

[melmoup]

Hi,
I'm trying to animate a view where the drawRect draws a rounded rect using UIBezierPath.
if I do the animation the rounded rect seems to be stretched and olny if I add setNeedsDisplay it's display correctly (but even with this just at the end of the animation).
Am I missing something?

    [UIView animateWithDuration:3.4 delay:0.0 options:0
                     animations:^{
                         self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.frame.size.width + 50.0, self.frame.size.height);
                         [self setNeedsDisplay];
                     }
                     completion:nil];

- (void)drawRect:(CGRect)rect
{
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:18.0];
    [[UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.5] setFill];
    [path fill];
    
    [[UIColor grayColor] setStroke];
    path.lineWidth = 1.0;
    [path stroke];
}