How to get original image when we zoom in and zoom out the image in ios

Question

Hi i am beginner in ios and in my project i am adding UIImage on UIScrollview and i have added tap gesture on UIImage

When we double click on UIImage then image should be zooming full screen size on view controller

After the full screen size image we can zoom it like any way what we want(i mean using like pinch zoom effect)here my requirement is when we double click on image then image need to set it's original position i have tried my level best but i did not get result please help me

my code is below:

#import "ViewController2.h"

@interface ViewController2 ()
{
    UIScrollView * myScroll;
    UITapGestureRecognizer *tap;
    BOOL isFullScreen;
    CGRect prevFrame;
    UIImageView * _imageView;
}

@end

@implementation ViewController2

- (void)viewDidLoad
{
    [super viewDidLoad];

    isFullScreen = FALSE;
    myScroll = [[UIScrollView alloc] init];
    myScroll.frame = self.view.bounds;
    myScroll.contentSize = CGSizeMake(_imageView.frame.size.width, _imageView.frame.size.height);
    myScroll.maximumZoomScale = 4.0;
    myScroll.minimumZoomScale = 1.0;
    myScroll.clipsToBounds = YES;
    myScroll.delegate = self;
    myScroll.backgroundColor = [UIColor lightGrayColor];
    [self.view addSubview:myScroll];

    _imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 10, 300, 200)];
    _imageView.contentMode = UIViewContentModeScaleAspectFill;
    [_imageView setClipsToBounds:YES];
    _imageView.userInteractionEnabled = YES;
    _imageView.image = [UIImage imageNamed:@"ram.jpeg"];

    UITapGestureRecognizer *tapper = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(imgToFullScreen:)];
    tapper.numberOfTapsRequired = 1;
    [_imageView addGestureRecognizer:tapper];
    [myScroll addSubview:_imageView];
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {

    return _imageView;
}

-(void)imgToFullScreen:(UITapGestureRecognizer*)sender {

    if (!isFullScreen) {

        [UIView animateWithDuration:0.5 delay:0 options:0 animations:^{

            prevFrame = _imageView.frame;
            [_imageView setFrame:[[UIScreen mainScreen] bounds]];
        }completion:^(BOOL finished){
            isFullScreen = TRUE;
        }];
        return;
    }
    else{
        [UIView animateWithDuration:0.5 delay:0 options:0 animations:^{
            [_imageView setFrame:prevFrame];
        }completion:^(BOOL finished){
            isFullScreen = FALSE;
        }];
        return;
    }
}

@end