For tracing objective-c messages: see http://www.unittested.com/2009/5/3/tracing-objective-c-messages

LoggerProxy.m

@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