#try/#catch doesn't catch exception - objective-c

Question

After upgrading Xcode from 6.0 to 6.3, I noticed my automated tests started failing.
2015-04-14 18:56:50.625 xctest[48304:517820] *** Terminating app due to uncaught exception 'foo', reason: 'bar'
*** First throw call stack:
(
0 CoreFoundation 0x0084a746 __exceptionPreprocess + 182
1 libobjc.A.dylib 0x004d3a97 objc_exception_throw + 44
2 CoreFoundation 0x0084a66d +[NSException raise:format:] + 141
3 TestTests 0x03e6dbdc -[TestTest test] + 810
4 CoreFoundation 0x0072b84d __invoking___ + 29
5 CoreFoundation 0x0072b6f8 -[NSInvocation invoke] + 360
6 XCTest 0x20108975 -[XCTestCase invokeTest] + 320
7 XCTest 0x20108baa -[XCTestCase performTest:] + 175
8 XCTest 0x20114122 -[XCTest run] + 314
9 XCTest 0x20107598 -[XCTestSuite performTest:] + 406
10 XCTest 0x20114122 -[XCTest run] + 314
11 XCTest 0x20107598 -[XCTestSuite performTest:] + 406
12 XCTest 0x20114122 -[XCTest run] + 314
13 XCTest 0x20107598 -[XCTestSuite performTest:] + 406
14 XCTest 0x20114122 -[XCTest run] + 314
15 XCTest 0x20103df2 __25-[XCTestDriver _runSuite]_block_invoke + 61
16 XCTest 0x20110c42 -[XCTestObservationCenter _observeTestExecutionForBlock:] + 184
17 XCTest 0x20103d16 -[XCTestDriver _runSuite] + 285
18 XCTest 0x20104961 -[XCTestDriver _checkForTestManager] + 272
19 XCTest 0x20104c79 -[XCTestDriver runTestSuite:completionHandler:] + 376
20 XCTest 0x2011772c +[XCTestProbe runTests:] + 216
21 libobjc.A.dylib 0x004e967e +[NSObject performSelector:withObject:] + 70
22 xctest 0x0000823a xctest + 4666
23 xctest 0x000084b0 xctest + 5296
24 xctest 0x00008591 xctest + 5521
25 xctest 0x00007e3d xctest + 3645
26 libdyld.dylib 0x019d4ac9 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
After further investigation it appears exceptions are now uncatchable. Both these snippets would cause this error.
XCTAssertThrows([NSException raise:#"foo" format:#"bar"]);
and
#try {
[NSException raise:#"foo" format:#"bar"];
}
#catch (NSException *ex) {
NSLog(#"caught");
}
After a VCS force clean sync and rebuild everything looked fine, but then the same failure started in a couple of builds time. Does anyone have any ideas?

Answer 1

Following the developer forums, this appears to be a bug or oversight in the developer tools that introduced an incompatibility with binaries built with older versions of the tools.
Should be fixed in Xcode 6.4