Using custom fonts in iOS apps cause the app to crash with a Segmentation Fault
For example:
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000010
VM Region Info: 0x10 is not in any region. Bytes before following region: 4301701104
REGION TYPE START - END [ VSIZE] PRT/MAX SHRMOD REGION DETAIL
UNUSED SPACE AT START
--->
__TEXT 000000010066c000-0000000100670000 [ 16K] r-x/r-x SM=COW ...a.app/<Appname>]
Termination Signal: Segmentation fault: 11
Termination Reason: Namespace SIGNAL, Code 0xb
Terminating Process: exc handler [0]
Triggered by Thread: 13
where Thread 13 is handling the Dispatch queue: Internal _UICache queue.
To summarise that: This happens because the UIFontDescriptor used to obtain fonts in font.ios.ts#l144 ff somehow references memory that gets deallocated using WTF::StringWrapperCFAllocator::deallocate(void*,void*) on a low memory warning which then tries to call a block on the mainthread which is not possible in that situation (?).
Thread 13 Queue : Internal _UICache queue (serial)
#0 0x000000010fb8338c in pthread_mutex_lock ()
#1 0x000000010f492a5b in CFRunLoopPerformBlock ()
#2 0x000000010b9ad826 in WTF::StringWrapperCFAllocator::deallocate(void*, void*) ()
#3 0x000000010f455077 in CFRelease ()
#4 0x000000010f4642b5 in __CFBasicHashDrain ()
#5 0x000000010f454d0c in CFRelease ()
#6 0x0000000111003446 in TDescriptor::~TDescriptor() ()
#7 0x000000010f454d0c in CFRelease ()
#8 0x000000010fc7fa1b in -[_UIFontCacheKey dealloc] ()
#9 0x000000010ebb2afe in objc_object::sidetable_release(bool) ()
#10 0x000000010f4a0850 in -[__NSDictionaryM removeAllObjects] ()
#11 0x000000010c9653eb in _dispatch_client_callout ()
#12 0x000000010c949ef5 in _dispatch_barrier_sync_f_invoke ()
#13 0x000000010fca5f7c in __16-[_UICache init]_block_invoke ()
#14 0x000000010c9653eb in _dispatch_client_callout ()
#15 0x000000010c9587e5 in _dispatch_source_latch_and_call ()
#16 0x000000010c953770 in _dispatch_source_invoke ()
#17 0x000000010c94d996 in _dispatch_root_queue_drain ()
#18 0x000000010c94d405 in _dispatch_worker_thread3 ()
#19 0x000000010fb855a2 in _pthread_wqthread ()
#20 0x000000010fb8507d in start_wqthread ()
To reproduce:
- clone the following repository: https://github.com/Buuhuu/nativescript-5019
- prepare the app using tns prepare ios
- open it in xcode open platform/ios/<projectfile>.xcodeproj
- run the app using xcode on simulator (simulator can send low memory signals)
- In the simulators Debug menu simulate memory warning
- The app crashs with the stacktrace shown above
Versions and so on
- tns-core-modules 3.3.0 (in the example above), 3.1.1 (in our production app)
- tns-ios: 3.2.0
Unfortunately I was not able to change the creation of UIFontDescriptor to resolve the issue. For my project I patched font.ios.js but wasn't able to implement the UIFontWeightTrait ... anyway I want to share my implementation of l144 ff:
var fontNamesForFamilyName = UIFont.fontNamesForFamilyName(fontFamily); // NSArray<String>
for (var i = 0, c = fontNamesForFamilyName.count; i < c; i++) {
var fontCanidate = UIFont.fontWithNameSize(fontNamesForFamilyName.objectAtIndex(i), size);
if (fontCanidate.familyName !== fontFamily) {
continue;
}
// now apply the symbolic traits
if (symbolicTraits) {
var fontDescriptor = utils.ios.getter(fontCanidate, fontCanidate.fontDescriptor);
fontDescriptor = fontDescriptor.fontDescriptorWithSymbolicTraits(symbolicTraits);
fontCanidate = UIFont.fontWithDescriptorSize(fontDescriptor, size);
}
if (font.isItalic) {
var fontDescriptor = utils.ios.getter(fontCanidate, fontCanidate.fontDescriptor);
var actualItalic = fontDescriptor.symbolicTraits & 1;
if (!actualItalic && EMULATE_OBLIQUE) {
fontDescriptor = fontDescriptor.fontDescriptorWithMatrix(OBLIQUE_TRANSFORM);
fontCanidate = UIFont.fontWithDescriptorSize(fontDescriptor, size);
}
}
result = fontCanidate;
break;
}
if (result.familyName === fontFamily) {
break;
}
else {
result = null;
}
Using custom fonts in iOS apps cause the app to crash with a Segmentation Fault
For example:
Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000010 VM Region Info: 0x10 is not in any region. Bytes before following region: 4301701104 REGION TYPE START - END [ VSIZE] PRT/MAX SHRMOD REGION DETAIL UNUSED SPACE AT START ---> __TEXT 000000010066c000-0000000100670000 [ 16K] r-x/r-x SM=COW ...a.app/<Appname>] Termination Signal: Segmentation fault: 11 Termination Reason: Namespace SIGNAL, Code 0xb Terminating Process: exc handler [0] Triggered by Thread: 13where Thread 13 is handling the Dispatch queue: Internal _UICache queue.
To summarise that: This happens because the UIFontDescriptor used to obtain fonts in font.ios.ts#l144 ff somehow references memory that gets deallocated using WTF::StringWrapperCFAllocator::deallocate(void*,void*) on a low memory warning which then tries to call a block on the mainthread which is not possible in that situation (?).
To reproduce:
Versions and so on
Unfortunately I was not able to change the creation of UIFontDescriptor to resolve the issue. For my project I patched font.ios.js but wasn't able to implement the UIFontWeightTrait ... anyway I want to share my implementation of l144 ff:
var fontNamesForFamilyName = UIFont.fontNamesForFamilyName(fontFamily); // NSArray<String> for (var i = 0, c = fontNamesForFamilyName.count; i < c; i++) { var fontCanidate = UIFont.fontWithNameSize(fontNamesForFamilyName.objectAtIndex(i), size); if (fontCanidate.familyName !== fontFamily) { continue; } // now apply the symbolic traits if (symbolicTraits) { var fontDescriptor = utils.ios.getter(fontCanidate, fontCanidate.fontDescriptor); fontDescriptor = fontDescriptor.fontDescriptorWithSymbolicTraits(symbolicTraits); fontCanidate = UIFont.fontWithDescriptorSize(fontDescriptor, size); } if (font.isItalic) { var fontDescriptor = utils.ios.getter(fontCanidate, fontCanidate.fontDescriptor); var actualItalic = fontDescriptor.symbolicTraits & 1; if (!actualItalic && EMULATE_OBLIQUE) { fontDescriptor = fontDescriptor.fontDescriptorWithMatrix(OBLIQUE_TRANSFORM); fontCanidate = UIFont.fontWithDescriptorSize(fontDescriptor, size); } } result = fontCanidate; break; } if (result.familyName === fontFamily) { break; } else { result = null; }