Capturing all methods/message calls on an object

cocoa, nsobject, objective-c

Solution

You can also use objective-c forwarding. Basically you can create a proxy object that logs the methods then forwards the call to the original. See my blog post for more details.

@interface LoggerProxy : NSObject
{
    id original;
}

- (id)initWithOriginal:(id) value;

@end
@implementation LoggerProxy

- (id) initWithOriginal:(id)value
{
    if (self = [super init]) {
        original = value;
    }
    return self;
}

- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel
{
    NSMethodSignature *sig = [super methodSignatureForSelector:sel];
    if(!sig)
    {
        sig = [original methodSignatureForSelector:sel];
    }
    return sig;
}

- (void)forwardInvocation:(NSInvocation *)inv
{
    NSLog(@"[%@ %@] %@ %@", original, inv,[inv methodSignature],
         NSStringFromSelector([inv selector]));
    [inv invokeWithTarget:original];
}

@end

Problem

How do I put a "hook" on an object so I can see what messages are being sent to it? (ie do an NSLog() every time a message is sent to an object). I think recall seeing this done before but I forget how. I am thinking it might help me track down why part of my code is not working.

Original source