How to animate while resizing UIView

I saw some material on the web, but still can't quite get to where I want. I need to animate my view downwards, making it's height bigger.

Here is my code so far. What's happening here, is that instead of my view resizing, it's just changing it's location a bit up. If I change the proprty instead of "bounds.size" to be "transform.scale.y", it's a little better, only this time it expands the view both up and down, not just downwards.

Another thing I'm not of : are these keys just CALayer properties ? where I can find a list of these keys?

I would really appreciate help here. Thanks!

int x = self.btnHead.frame.origin.x;
int y = self.btnHead.frame.origin.y;
int height = self.btnHead.frame.size.height;
int width = self.btnHead.frame.size.width;


CABasicAnimation *resizeAnimation = [CABasicAnimation animationWithKeyPath:@"bounds.size"];
[resizeAnimation setToValue:[NSValue valueWithCGSize:CGSizeMake(width,height+50)]];
resizeAnimation.fillMode = kCAFillModeForwards;
resizeAnimation.removedOnCompletion = NO;

CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
animationGroup.animations = [NSArray arrayWithObjects:resizeAnimation,nil];
animationGroup.removedOnCompletion = NO;
animationGroup.fillMode = kCAFillModeForwards;
animationGroup.removedOnCompletion=NO;
animationGroup.duration = 0.1;

[self.btnHead.layer addAnimation:animationGroup forKey:@"animations"];

Edit: posting my first code as requested - This will just change my view size, but won't animate , no matter the duration I enter.

    int x = self.btnHead.frame.origin.x;
    int y = self.btnHead.frame.origin.y;
    int height = self.btnHead.frame.size.height;
    int width = self.btnHead.frame.size.width;


    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:10];
    CGRect rect = CGRectMake(x,y,width ,height+BUTTON_HEIGH*2);

    self.btnHead.frame = rect;

    [UIView commitAnimations];