I am running the following code on my phone, where 'object' is a Cat, which is a subclass of Animal. Animal has a property 'color':
NSLog(@"Object: %@", object); NSLog(@"Color: %@", [object color]); NSMethodSignature *signature = [[object class] instanceMethodSignatureForSelector:@selector(color)]; NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature]; [invocation setTarget:object]; [invocation invoke];
The output in my console is:
2009-06-28 16:17:07.766 MyApplication[57869:20b] Object: <Cat: 0xd3f370> 2009-06-28 16:17:08.146 MyApplication[57869:20b] Color: <Color: 0xd3eae0>
Then, I get the following error:
*** -[Cat <null selector>]: unrecognized selector sent to instance 0xd3f370
Any clues? I'm using this similar method in other classes, but I can't figure out what I'm doing wrong in this instance. The selector 'color' obviously exists, but I don't know why it isn't being properly recognized.
Try something like this:
You were missing a call to
NSMethodSignaturerecords type information for the arguments and return value of a method, but doesn't contain the selector itself. So if you want to use it with an
NSInvocationyou need to set the invocation's selector as well.