Open Radar

 
Our app uses a custom NSLayoutManager and a NSTextStorage. In a recent Sierra beta, this stopped working. As a result, our app has become unusable: it's text editor is blank and doesn't accept input.

I've isolated the problem to using our custom layout manager, and have attached a zip file that contains 1) the source code for a very simple application that exhibits the error and 2) this application compiled on El Capitan.

The included application, LayoutManagerBug_ElCap, works fine on El Capitan but won't show text or accept input on Sierra. So, this isn't just an issue with compiling on Sierra - it affects applications compiled on El Cap as well.

This is quite urgent for us, and we hope you have a fix, or a suggested workaround, for us soon.

Steps to Reproduce:
1. Run the included application, LayoutManagerBug_ElCap, on the most recent Sierra beta.
2. Notice how it does not display the appropriate text ("This is a test.") and doesn't allow any input.

In the included source:
1. Compile and run the attached project on Sierra.
2. Notice how the app does not display the appropriate text ("This is a test.") and doesn't allow any input.
3. In the following code, change the "#if 1" (which creates a "custom" layout manager) to an "#if 0":

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
#if 1
    // Create our own layout manager
    NSLayoutManager *lm = [[NSLayoutManager alloc] init];
    [lm addTextContainer:self.textView.textContainer];
#else
    // If we don't create our own layout manager, everything
    // works fine. To test, change the "#if 1" above to an "#if 0".
    NSLayoutManager *lm = self.textView.layoutManager;
#endif
    
    // Create our own text storage
    _textStorage = [[NSTextStorage alloc] init];
    [lm replaceTextStorage:self.textStorage];
    
    // Add "This is a test." to our own text storage.
    // We expect to see this in our text view.
    NSAttributedString *aString =[[NSAttributedString alloc] initWithString:@"This is a test."];
    [self.textStorage appendAttributedString:aString];
}

4. Run again.
5. Revel in a working application.

Expected Results:
The application that is compiled on El Cap and works on El Cap should also work in Sierra.

Actual Results:
The application does not display the appropriate text ("This is a test.") and doesn't allow any input.

Version:
OS: 10.12 Beta (16A304a)
Xcode: Version 8.0 beta 6 (8S201h)

Notes:
Perhaps this is why Xcode 7 crashes in Sierra?
http://stackoverflow.com/questions/38903699/xcode-7-3-1-crashes-on-macos-sierra-beta-5

Configuration:
This occurs on computers running recent Sierra betas