Pinch zoom doesn't work in scrollview

Question

I can scroll the image view, but pinch to zoom in/out does not work. Where went wrong?

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIImage *chosenImage = info[UIImagePickerControllerOriginalImage];

    UIImageView *imageView = [[UIImageView alloc] init];
    [self.scrollView addSubview:imageView];
    imageView.frame = CGRectMake(0, 0, chosenImage.size.width, chosenImage.size.height);

    imageView.image = chosenImage;

    self.scrollView.maximumZoomScale = 4;
    self.scrollView.minimumZoomScale = 0.1;
    self.scrollView.showsVerticalScrollIndicator=YES;
    self.scrollView.delegate = self;
    self.scrollView.scrollEnabled=YES;
    self.scrollView.userInteractionEnabled=YES;

    self.scrollView.contentSize = CGSizeMake(chosenImage.size.width, chosenImage.size.height);

    [picker dismissViewControllerAnimated:YES completion:NULL];
}

Answer 1

The first of all make sure your views have the correct delegates implemented. For example in the .m file

@interface myViewController () <UIGestureRecognizerDelegate, UIScrollViewDelegate>

The UIScrollView class can have a delegate that must adopt the UIScrollViewDelegate protocol. For zooming and panning to work, the delegate must implement both viewForZoomingInScrollView: and scrollViewDidEndZooming:withView:atScale:; in addition, the maximum (maximumZoomScale) and minimum ( minimumZoomScale) zoom scale must be different.

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
  return self.fullScreenView;
}




-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
    {
    }