Question

I am getting a Exc_Bad_Access error in main when I try to scroll my UIScrollView. This program is simple. I have A UIViewController added in AppDelegate. Then, here is the code in the ViewController. This works fine for scrolling but as soon as I add tmpScrollView.delegate = self. The program won’t scroll or zoom and gives me the Exc_Bad_Access error when I try to zoom.

@interface MainViewController : UIViewController &ltUIScrollViewDelegate>
@property (nonatomic,retain) UIScrollView *tmpScrollView;
@property (nonatomic,retain) UIView *containerView;
@end

- (void)viewDidLoad
{
[super viewDidLoad];

// Do any additional setup after loading the view.
tmpScrollView = [[UIScrollView alloc] initWithFrame:self.view.frame];
tmpScrollView.delegate = self;
[self.view addSubview:tmpScrollView];

// Set up the container view to hold our custom view hierarchy
CGSize containerSize = CGSizeMake(640.0f, 640.0f);
self.containerView = [[UIView alloc] initWithFrame:(CGRect){.origin=CGPointMake(0.0f, 0.0f), .size=containerSize}];
[self.tmpScrollView addSubview:self.containerView];

// Set up custom view hierarchy
UIView *redView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 640.0f, 80.0f)];
redView.backgroundColor = [UIColor redColor];
[self.containerView addSubview:redView];

UIView *blueView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 560.0f, 640.0f, 80.0f)];
blueView.backgroundColor = [UIColor blueColor];
[self.containerView addSubview:blueView];

UIView *greenView = [[UIView alloc] initWithFrame:CGRectMake(160.0f, 160.0f, 320.0f, 320.0f)];
greenView.backgroundColor = [UIColor greenColor];
[self.containerView addSubview:greenView];

UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"slow.png"]];
imageView.center = CGPointMake(320.0f, 320.0f);
[self.containerView addSubview:imageView];

//Tell the scroll view the size of the contents
self.tmpScrollView.contentSize = containerSize;
}

-(void)viewWillAppear:(BOOL)animated
{
NSLog(@"Will Appear");
[super viewWillAppear:animated];

// Set up the minimum & maximum zoom scales
CGRect scrollViewFrame = self.tmpScrollView.frame;
CGFloat scaleWidth = scrollViewFrame.size.width / self.tmpScrollView.contentSize.width;
CGFloat scaleHeight = scrollViewFrame.size.height / self.tmpScrollView.contentSize.height;
CGFloat minScale = MIN(scaleWidth, scaleHeight);

self.tmpScrollView.minimumZoomScale = minScale;
self.tmpScrollView.maximumZoomScale = 1.0f;
self.tmpScrollView.zoomScale = minScale;

//***** Here is the line for setting the delegate
self.tmpScrollView.delegate = self;

[self centerScrollViewContents];
}


-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
NSLog(@"End Zoom");
}

-(UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView {
// Return the view that we want to zoom
return self.containerView;
}

-(void)scrollViewDidZoom:(UIScrollView *)scrollView {
// The scroll view has zoomed, so we need to re-center the contents
[self centerScrollViewContents];
}
@end

Thanks for any help. This has been driving me crazy for a day now…

Edit: Adding centerScrollViewContens too:

- (void)centerScrollViewContents {
    CGSize boundsSize = self.tmpScrollView.bounds.size;
    CGRect contentsFrame = self.containerView.frame;

    if (contentsFrame.size.width < boundsSize.width) {
        contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2.0f;
    } else {
        contentsFrame.origin.x = 0.0f;
    }

    if (contentsFrame.size.height < boundsSize.height) {
        contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0f;
    } else {
        contentsFrame.origin.y = 0.0f;
    }

    self.containerView.frame = contentsFrame;
}

Answer 1

Whatever Code you have provided is working fine on my end.May be there could be some sort of problem in your “centerScrollViewContents” method.Can you post the code for this method also???