Set content size of scrollview relative to transform on zooming by UIPinchGestureRecognizer

Question

I have scrollview and added UIPinchGestureRecognizer to scrollview. Now on gesture event I have zoom in or out scrollview and its handle action is as following :

static float lastScale = 1.0;

- (void)handlePinchGesture:(UIPinchGestureRecognizer *)gestureRecognizer
{

    if([gestureRecognizer state] == UIGestureRecognizerStateBegan) {
    // Reset the last scale, necessary if there are multiple objects with different scales
        lastScale = [gestureRecognizer scale];
    }

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged)
    {
        CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];

        // Constants to adjust the max/min values of zoom
        const CGFloat kMaxScale = 2.0;
        const CGFloat kMinScale = 1.0;

        CGFloat newScale = 1 -  (lastScale - [gestureRecognizer scale]);
        newScale = MIN(newScale, kMaxScale / currentScale);
        newScale = MAX(newScale, kMinScale / currentScale);
        CGAffineTransform transform = CGAffineTransformScale([[gestureRecognizer view] transform], newScale, newScale);
        [gestureRecognizer view].transform = transform;

        lastScale = [gestureRecognizer scale];  // Store the previous scale factor for the next pinch gesture call
    }
}

I want to change contentSize in this method. Now, my question is that how to set scrollview content size so that after zoom out I can scroll to see all the content in scrollview.

Please help.

Answer 1

@interface HorizontalScrollView ()
{
    UIView *container;
}
@end

@implementation HorizontalScrollView
@synthesize scrlView;

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    container = [[UIView alloc]initWithFrame:CGRectMake(0, 0, self.scrlView.frame.size.width, self.scrlView.frame.size.height)];


    UIImage *image = [UIImage imageNamed:@"1.jpeg"];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
    CGRect rect = imageView.frame;
    rect.size.height = 215;
    rect.size.width = self.scrlView.frame.size.width;
    rect.origin = CGPointMake(0, 0);
    imageView.frame = rect;
    [container addSubview:imageView];

    [scrlView addSubview:container];

    self.scrlView.minimumZoomScale=1.0;
    self.scrlView.maximumZoomScale=6.0;
    self.scrlView.delegate=self;

    // set the content size so it can be scrollable
    [self.scrlView setContentSize:CGSizeMake(1*self.scrlView.frame.size.width, 0)];
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return container;
}