UIScrollView setContentSize doesn't work

Question

I have a really big problem with UIScrollView. To make sure it wasn't my actual project, I created a NEW project, iPhone only, for iOS 6 and 7. I disabled autolayout.

1. I created a Tab Bar project
2. I created a view controller, embedded it in a navigation controller and connected it as Tab bar item #0
3. I put a UIScrollView in my view.
4. I connected the scrollview in the custom UIViewController created for this view.
5. I synthesized my IBOutlet and set the delegate to self. I also implemented delegate in .h

Here is my code (ViewDidLoad):

    self.scrollView.delegate = self;
    [self.scrollView setScrollEnabled:YES];

    [self.scrollView setContentSize:CGSizeMake(self.view.frame.size.width, 20000)];


    NSLog(@"contentSize width %f", self.scrollView.contentSize.width);
    NSLog(@"contentSize height %f", self.scrollView.contentSize.height);

    NSLog(@"%@", NSStringFromCGAffineTransform(self.scrollView.transform));

It returns me "contentSize width 20000.000000", "contentSize height 0.000000 " and "[1, 0, 0, 1, 0, 0]". It scrolls left-right where it should scroll up-down

Please help!

Answer 1

I had the same issue until I realized I hadn't set the UIScrollView delegate. Also, if you're using auto layout, you need to wait for the layout to be applied to the UIScrollView. This means you should set the Content Size in "viewDidLayoutSubviews".

Answer 2

Use this code. ScrollView setContentSize should be called async in main thread.

Swift:

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    DispatchQueue.main.async {
        var contentRect = CGRect.zero

        for view in self.scrollView.subviews {
           contentRect = contentRect.union(view.frame)
        }

        self.scrollView.contentSize = contentRect.size
    }
}

Objective C:

 - (void)viewDidLayoutSubviews {
     [super viewDidLayoutSubviews];

     dispatch_async(dispatch_get_main_queue(), ^ {
                        CGRect contentRect = CGRectZero;

                        for(UIView *view in scrollView.subviews)
                           contentRect = CGRectUnion(contentRect,view.frame);

                           scrollView.contentSize = contentRect.size;
                       });
}

Answer 3

In viewDidLoad method, frame may not be correct, move the code to this method:

- (void)viewWillLayoutSubviews
{
    [super viewWillLayoutSubviews];

    // Your code

}

Answer 4

Okay, there is absolutely nothing wrong with your code. So some suggestions:

1. Make sure you added to your .h file like so:

   @interface yourViewController : UIViewController <UIScrollViewDelegate> {
   
    }
   

2. Try moving this snippet of code to the "viewWillLoad" method:

   - (void)viewWillAppear:(BOOL)animated {
        self.scrollView.delegate = self;
        [self.scrollView setScrollEnabled:YES];
   
        [self.scrollView setContentSize:CGSizeMake(self.view.frame.size.width, 20000)];
   }