Swift crash/Obj-C warning when setting numerator on MIKMutableMIDIMetaTimeSignatureEvent

[pwightman]

The following Objective-C:

MIKMutableMIDIMetaTimeSignatureEvent *event = [[MIKMutableMIDIMetaTimeSignatureEvent alloc] init];
event.numerator = 4;

Yields the following warning in the console:

[NSConcreteMutableData replaceBytesInRange:withBytes:length:]: range {0, 1} exceeds data length 0

but does not crash. The following Swift:

let event = MIKMutableMIDIMetaTimeSignatureEvent()
event.numerator = UInt8(4)

Raises an NSRangeException:

*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSConcreteMutableData subdataWithRange:]: range {8, 4026531840} exceeds data length 0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010ad36b95 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010c88bbb7 objc_exception_throw + 45
    2   CoreFoundation                      0x000000010ad36acd +[NSException raise:format:] + 205
    3   Foundation                          0x000000010b1812b7 -[NSData(NSData) subdataWithRange:] + 252
    4   MIKMIDI                             0x000000010cacb24d -[MIKMIDIMetaEvent metaData] + 237
    5   MIKMIDI                             0x000000010cacdb53 -[MIKMIDIMetaTimeSignatureEvent setNumerator:] + 243

The length of the range (4026531840) is different every time I run it.

MIKMutableMIDIMetaTimeSignatureEvent, MIKMIDIMetaTimeSignatureEvent and MIKMIDIMetaEvent all don't have constructors, so it falls all the way back to MIKMIDIEvent, and initializes as a NULL event type with empty internalData. So when it accesses metadata, its dataLength is a garbage value. Or at least I think that's what's going on.

[pwightman]

So the Objective-C actually gets past the metadata call (where Swift is crashing) and warns about the next line.

[armadsen]

Nice catch. I'll fix this tomorrow morning (if you don't get to it before me).

On Feb 24, 2015, at 10:08 PM, Parker [email protected] wrote:

So the Objective-C actually gets past the metadata call (where Swift is crashing) and warns about the next line.

�
Reply to this email directly or view it on GitHub.

[armadsen]

Should be fixed.