Changing frame of a UIView doesn't update its frame in its parent's subviews array. Hence the position doesn't changes

Question

I am fairly new to IOS App Development. I have a view with 2 UIView and 1 ScrollView. One of the UIView is a footer which I want to be animated in such a way that it will hide/show to/from out of the screen based on some condition. However when I change the frame of the footer(show/hide footer), nothing happens.

So I did a NSLog of the footer and the self.view.subviews[2] and found that the frame of footer has changed successfully but the same change has not been reflected in the self.view.

If I do [self.view addSubview:footer] every time I call hideFooter/showFooter solves my problem but it messes up bad with my scroll view (which I cannot rectify, so this is not an option).

Am I missing something here? Is there a way to modify frame of a UIView such that the changes reflect in the UI too? (I have read most of the answers on modifying frame of a UIView. None seems to work without adding the UIView again to self.view).

Note that I have declared footer globally in the class just inside @implementation and have initialized it only once inside a method called from viewDidLoad.

@implementation PlayAudioViewController
UIButton *play;
UIButton *next;
UIButton *previous;
UIView* header;
UIView* footer;

- (void)viewDidLoad
{
    [self addFooter];
}
-(void)addFooter{

    footer = [[UIView alloc]initWithFrame:CGRectMake(0, self.view.frame.size.height * 1, self.view.frame.size.width, self.view.frame.size.height * 0.1)];
    UIImageView *headerImage = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height * 0.1)];
    headerImage.image = [UIImage imageNamed:@"Wooden-Background.jpg"];

    [footer addSubview:headerImage];
    footer.backgroundColor = [UIColor redColor];

    queue = [[NSMutableArray alloc] init];
    play = [[UIButton alloc]initWithFrame:CGRectMake(footer.frame.size.width * 0.475, footer.frame.size.height * 0.10, footer.frame.size.height * 0.80, footer.frame.size.height * 0.80)];
    [play setBackgroundImage:[UIImage imageNamed:@"play_1.png"] forState:UIControlStateNormal];
    [play setBackgroundImage:[UIImage imageNamed:@"stop.png"] forState:UIControlStateSelected];
    [play addTarget:self action:@selector(universalplay:) forControlEvents: UIControlEventTouchUpInside];
    play.enabled = YES;
    [footer addSubview:play];

    next = [[UIButton alloc]initWithFrame:CGRectMake(footer.frame.size.width * 0.675, footer.frame.size.height * 0.20, footer.frame.size.height * 0.60, footer.frame.size.height * 0.60)];
    [next setBackgroundImage:[UIImage imageNamed:@"next.png"] forState:UIControlStateNormal];
    [next addTarget:self action:@selector(nextplay:) forControlEvents: UIControlEventTouchUpInside];
    next.enabled=NO;
    [footer addSubview:next];

    previous = [[UIButton alloc]initWithFrame:CGRectMake(footer.frame.size.width * 0.29, footer.frame.size.height * 0.20, footer.frame.size.height * 0.60, footer.frame.size.height * 0.60)];
    [previous setBackgroundImage:[UIImage imageNamed:@"previous.png"] forState:UIControlStateNormal];
    [previous addTarget:self action:@selector(previousplay:) forControlEvents: UIControlEventTouchUpInside];
    previous.enabled=NO;
    [footer addSubview:previous];
    NSLog(@"%@", footer.subviews[1]);
    [self.view addSubview:footer];

    [self hideFooter];
}

-(void)showFooter{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:2];
    footer.frame = CGRectMake(0, self.view.frame.size.height * 0.9, self.view.frame.size.width, self.view.frame.size.height * 0.1);
    //[self.view addSubview:footer];
    [UIView commitAnimations];
    NSLog(@"%@", self.view.subviews[0]);
    NSLog(@"%@", self.view.subviews[1]);
    NSLog(@"%@", ((UIButton *)((UIView *)self.view.subviews[2]).subviews[1]));

}

-(void)hideFooter{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:2];
    footer.frame = CGRectMake(0, self.view.frame.size.height * 1, self.view.frame.size.width, self.view.frame.size.height * 0.1);
    //[self.view addSubview:footer];
    [UIView commitAnimations];
}

As stated earlier, if I uncomment the commented statement in addFooter and showFooter, animation works perfectly but my scrollView gets screwed(newly added subviews stop getting reflected).

Also I am facing similar problem with play, pause and next button. These buttons will be enabled or disabled time to time. When I am changing their .enable property, the change is again not reflected in the self.view.

Please help me understand the reason behind this unusual behavior.