Question

I am trying to detect what formatting will be applied to new text being entered by the user. Meaning the cursor has a position, but no text selection (i.e. length = 0). Every time I try to query typingAttributes, even if it’s just to log, the app crashes.

Thread 1:EXC_BAD_ACCESS (code=2, address=0x4)

In the Debug Navigator the last thing that happens is:

WebCore::Frame::styleAtSelectionStart() const

And just before that, I see

-[UITextView typingAttributes]

If I log with a selectedRange.length greater than 0, it seems to be fine. I’ve tried running with Zombies and Guard Malloc enabled, but am not seeing anything.

In my test project, the crash occurs as soon as the UITextView becomes firstResponder:

- (void)textViewDidChangeSelection:(UITextView *)textView
{
    [self updateFormatButtons];
}

Which calls to check the attributes:

- (void)updateFormatButtons
{    
    UITextView *problemTextView = [self synopsisTextView];
    NSRange selectedRange = [self getSelectedTextRange];
    if (selectedRange.length == 0) // No text selected
    {
     // HELP - Why does the following line cause a crash?
     // NSLog(@"textViewFormatting options: %@", [problemTextView typingAttributes]);
    }
    else
    {
       NSLog(@"Some text selected"); // Fine here
       NSLog(@"textViewFormatting options: %@", [problemTextView typingAttributes]);
    }
}

based on the selected range:

- (NSRange)getSelectedTextRange
{ 
    NSRange rangeToReturn = NSMakeRange(NSNotFound, 0);
    UITextView *textView = [self synopsisTextView];
    if ([textView isFirstResponder])
    {
        rangeToReturn = [textView selectedRange];
    }
    return rangeToReturn;
}

Suggestions appreciated.

Answer 1

The issue appears to have been that when the text view’s selection changes, the contents of the typingAttributes dictionary are cleared automatically. So having the dictionary queried immediately was causing some kind of conflict. Putting a delay before calling seems to have addressed it:

[self performSelector:@selector(updateFormatButtons) withObject:nil afterDelay:0.15];