Christopher Burnett Christopher Burnett - 5 months ago 11
Objective-C Question

Getting argument values from NSInvocation

Could someone please explain how to go about getting the values passed to a non-existant method that is being intercepted when using:

+ (void)forwardInvocation:(NSInvocation *)anInvocation;

+ (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector;


Given a message like:

[SomeClass doSomething:@"theThing" withSomething:@"aParam"];


I can get the method signature without a problem but I am terribly confused about how to get the values that were passed in with it.

Am I totally off base in when I should use these methods or just missing something?

Answer

-[NSInvocation getArgument:atIndex:]

So in your case, you would use it like:

__unsafe_retained NSString * firstArgument = nil;
__unsafe_retained NSString * secondArgument = nil;
[theInvocation getArgument:&firstArgument atIndex:2];
[theInvocation getArgument:&secondArgument atIndex:3];
NSLog(@"Arguments: %@ and %@", firstArgument, secondArgument);

Remember that self and _cmd are arguments 0 and 1.