> On Dec 13, 2014, at 7:20 AM, Maxthon Chan <m...@maxchan.info> wrote: > > This got me scratching my head, hard. Why would class_respondsToSelector() > crash? (BTW this is used in a class search loop so I cannot use [NSObject > respondsToSelector:] just yet.) > > /Users/technix/Developer/Subtitler > Pro/Frameworks/SubtitleKit/SubtitleKitTests/SKSubripParseTest.m:33: error: > -[SKSubripParseTest testFileFormatSearch] : failed: caught > "NSRangeException", "*** -[__NSCFString substringFromIndex:]: Index 18 out of > bounds; string length 17" > ( > 0 CoreFoundation 0x00007fff9266666c > __exceptionPreprocess + 172 > 1 libobjc.A.dylib 0x00007fff8725976e > objc_exception_throw + 43 > 2 CoreFoundation 0x00007fff9266651d > +[NSException raise:format:] + 205 > 3 Foundation 0x00007fff8f127b2e -[NSString > substringFromIndex:] + 118 > 4 AppKit 0x00007fff8a4e1c49 > +[_NSObjectAnimator _targetClass] + 92 > 5 AppKit 0x00007fff8a4e1b79 > +[_NSObjectAnimator resolveInstanceMethod:] + 34 > 6 libobjc.A.dylib 0x00007fff8725c954 > _ZL28_class_resolveInstanceMethodP10objc_classP13objc_selectorP11objc_object > + 80
From this call stack it looks like you are tripping over an internal implementation detail of AppKit in a way that is not expected. In particular, +[_NSObjectAnimator _targetClass] (an internal class) is calling -[NSString substringFromIndex:] and passing an invalid index, probably due to some implementation detail that your code is violating. Given you are inside +resolveInstanceMethod:, my guess would be that by trying to dynamically look up the instance method, you are tripping over code that determines where to get that instance method from that doesn’t expect to be called on the raw _NSObjectAnimator. My minimal recommendation would be to filter out all classes that begin with an “_” prefix from your scan. But I would be curious as to why you need to know the subclass information up front and not just as you encounter particular classes (granted this is for a test it seems, but it seems like it would be prudent to reduce your test to a more reasonable scope). > 7 libobjc.A.dylib 0x00007fff87262799 > lookUpImpOrForward + 356 > 8 libobjc.A.dylib 0x00007fff87262617 > lookUpImpOrNil + 20 > 9 libobjc.A.dylib 0x00007fff872545ff > class_respondsToSelector + 37 > 10 SubtitleKit 0x00000001000d02c8 +[SKFormat > formatEngineForExtension:] + 184 > 11 SubtitleKitTests 0x000000010008551e > -[SKSubripParseTest testFileFormatSearch] + 142 > 12 CoreFoundation 0x00007fff9253f3cc > __invoking___ + 140 > 13 CoreFoundation 0x00007fff9253f222 > -[NSInvocation invoke] + 290 > 14 XCTest 0x0000000100097919 -[XCTestCase > invokeTest] + 253 > 15 XCTest 0x0000000100097b1a -[XCTestCase > performTest:] + 150 > 16 XCTest 0x00000001000a0700 -[XCTest > run] + 257 > 17 XCTest 0x000000010009682b > -[XCTestSuite performTest:] + 379 > 18 XCTest 0x00000001000a0700 -[XCTest > run] + 257 > 19 XCTest 0x000000010009682b > -[XCTestSuite performTest:] + 379 > 20 XCTest 0x00000001000a0700 -[XCTest > run] + 257 > 21 XCTest 0x000000010009682b > -[XCTestSuite performTest:] + 379 > 22 XCTest 0x00000001000a0700 -[XCTest > run] + 257 > 23 XCTest 0x000000010009383c > __25-[XCTestDriver _runSuite]_block_invoke + 56 > 24 XCTest 0x000000010009f36d > -[XCTestObservationCenter _observeTestExecutionForBlock:] + 162 > 25 XCTest 0x0000000100093770 > -[XCTestDriver _runSuite] + 269 > 26 XCTest 0x0000000100094359 > -[XCTestDriver _checkForTestManager] + 678 > 27 XCTest 0x00000001000a35b0 > +[XCTestProbe runTests:] + 182 > 28 xctest 0x0000000100001256 xctest + 4694 > 29 xctest 0x00000001000015d6 xctest + 5590 > 30 xctest 0x0000000100000ed3 xctest + 3795 > 31 libdyld.dylib 0x00007fff90e315c9 start + 1 > ) > > _______________________________________________ > > Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/david.duncan%40apple.com > > This email sent to david.dun...@apple.com -- David Duncan _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
