更新NSTextStorage字体时崩溃

Question

My UITextView responds to UIContentSizeCategoryDidChangeNotification to respond to dynamic font changes, and I implemented the following code:

 NSTextStorage * textStorage = [self textStorage];
[textStorage beginEditing];
[textStorage enumerateAttribute: NSFontAttributeName
                        inRange: NSMakeRange(0, [textStorage length])
                        options: 0
                     usingBlock: ^(id value, NSRange range, BOOL * stop) {
                         UIFont *newFont = [UIFont fontWithDescriptor: [UIFontDescriptor preferredFixedFontDescriptorWithTextStyle: IDFontTextStyleFixed] size: 0.0f];

                         if (newFont) {
                             [textStorage removeAttribute: NSFontAttributeName
                                                    range: range];
                             [textStorage addAttribute: NSFontAttributeName
                                                 value: newFont
                                                 range: range];
                         }
                     }];

[textStorage endEditing];

It always crashes on the last line, [textStorage endEditing]; . I have enabled exception breakpoints, but there is no additional information in the debug pane see the backtrace below. If I remove 'beginEditing and endEditing , it crashes on the removeAttribute line. I'm using [UIFont fontWithDescriptor: [UIFontDescriptor preferredFixedFontDescriptorWithTextStyle: IDFontTextStyleFixed] size: 0.0f]; all over my app, and it works everywhere, except for in the UITextView .

Anyone sees what's going wrong and how I could fix it?

EDIT: here's the backtrace:

    (lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=2, address=0x10f3c0060)
    frame #0: 0x000000010c77f29d libobjc.A.dylib`realizeClass(objc_class*) + 145
    frame #1: 0x000000010c783125 libobjc.A.dylib`lookUpImpOrForward + 127
    frame #2: 0x000000010c792554 libobjc.A.dylib`_objc_msgSend_uncached + 68
    frame #3: 0x0000000118d39ce7 UIFoundation`-[NSGlyphGenerator generateGlyphsForGlyphStorage:desiredNumberOfCharacters:glyphIndex:characterIndex:] + 251
    frame #4: 0x0000000118d06d47 UIFoundation`-[NSLayoutManager(NSPrivate) _fillGlyphHoleForCharacterRange:startGlyphIndex:desiredNumberOfCharacters:] + 736
    frame #5: 0x0000000118d091b0 UIFoundation`_NSFastFillAllGlyphHolesForCharacterRange + 726
    frame #6: 0x0000000118d47f2e UIFoundation`-[NSLayoutManager glyphRangeForCharacterRange:actualCharacterRange:] + 64
    frame #7: 0x0000000118d071af UIFoundation`-[NSLayoutManager(NSPrivate) _fillLayoutHoleForCharacterRange:desiredNumberOfLines:isSoft:] + 617
    frame #8: 0x0000000118d08e9a UIFoundation`-[NSLayoutManager(NSPrivate) _fillLayoutHoleAtIndex:desiredNumberOfLines:] + 208
    frame #9: 0x0000000118d0954a UIFoundation`-[NSLayoutManager(NSPrivate) _markSelfAsDirtyForBackgroundLayout:] + 325
    frame #10: 0x0000000118d13d10 UIFoundation`-[NSLayoutManager(NSPrivate) _invalidateLayoutForExtendedCharacterRange:isSoft:invalidateUsage:] + 2212
    frame #11: 0x0000000118d44743 UIFoundation`-[NSLayoutManager textStorage:edited:range:changeInLength:invalidatedRange:] + 226
    frame #12: 0x0000000118d448f9 UIFoundation`-[NSLayoutManager processEditingForTextStorage:edited:range:changeInLength:invalidatedRange:] + 47
    frame #13: 0x0000000118d6c216 UIFoundation`-[NSTextStorage _notifyEdited:range:changeInLength:invalidatedRange:] + 168
    frame #14: 0x0000000118d6bd4c UIFoundation`-[NSTextStorage processEditing] + 372
    frame #15: 0x0000000118d6b995 UIFoundation`-[NSTextStorage endEditing] + 83
  * frame #16: 0x000000010bee435b MyApp`-[MyUITextView updateFonts](self=0x00007fc26208c000, _cmd="updateFonts") at MyUITextView.m:107 

Answer 1

OK, I solved it.

I am using a helper class to handle the NSTextStorage , NSTextContainer , and NSLayoutManager objects. When creating MyTextView , I didn't hold on to the helper object (I only passed the textContainer to init of MyTextView ). I now made the helper object a @property of MyTextView so it has a strong reference, and the crash is gone.