Calling topLayoutGuide breaks scrolling altogether?

Question

I am having weird issues with the topLayoutGuide method, which I have to use in a situation where setAutomaticallyAdjustsScrollViewInsets: doesn't work. To narrow down the cause of the problem, I've created the following minimal example, which just sets up a basic table view for testing:

1. Set up a new iOS Single View application in Xcode.

2. Paste the following code in ViewController.m's implementation:

   @implementation ViewController
   
   - (void)loadView
   {
       [self setTableView:[[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStylePlain]];
   }
   
   - (void)viewDidLoad
   {
       [super viewDidLoad];
       [self setAutomaticallyAdjustsScrollViewInsets:NO]; // [*]
   }
   
   - (void)viewDidLayoutSubviews
   {
       UITableView *tableView = [self tableView];
   
       UIEdgeInsets insets = [tableView contentInset];
       // insets.top = [[self topLayoutGuide] length]; // [1]
       // insets.top = 100;                            // [2]
   
       [tableView setContentInset:insets];
       [tableView setScrollIndicatorInsets:insets];
   }
   
   #pragma mark - Table view data source
   
   - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
   {
       return 100;
   }
   
   - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
   {
       static NSString *CellIdentifier = @"Cell";
   
       UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
   
       if (cell == nil) {
           cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
       }
   
       [[cell textLabel] setText:[NSString stringWithFormat:@"%d", [indexPath row]]];
   
       return cell;
   }
   
   @end
   

The issues that I'm having are these:

1. If I uncomment the line marked with [1], the correct inset is applied, but scrolling the table view no longer works. When I try to scroll, the table just bounces back to the initial scroll position after I release my finger. This behaviour is also triggered by a plain call to [self topLayoutGuide], without assigning the result to anything.

2. If I uncomment line [2] instead of [1], scrolling works. The inset of 100 pt is applied as well. But now the initial scrolling position is automatically adjusted so that the content underlaps the status bar.

([*]: This really only seems to do anything in combination with a containing navigation controller. I doesn't seem to make a difference in this example, but I want to disable any automatic behaviour just to be sure.)

Is there anything obvious I'm doing wrong? I'm really at a loss here.

Answer 1

This is definitely a bug in iOS 7 (doesn't appear to be fixed in 7.1) but seems to only affect UITableViewControllers. I switched over to using a UIViewController with an embedded UITableView since I am not using static cells and don't need any of the 'magic' that a UITableViewController gives you.

Once I wired up the UITableViewDataSource and UITableViewDelegate manually I was able to start using self.topLayoutGuide without messing up the tableView's contentSize.

This was an acceptable workaround for me until Apple fixes the bug.

Answer 2

Same thing to me, instead of getting the topLayoutGuide, try this:

CGFloat topOffset = CGRectGetMaxY(self.refController.navigationController.navigationBar.frame);