Instance method invocation logger

example

UIBezierPath *apath      = [UIBezierPath bezierPath];
InvocationLogger *logger = [InvocationLogger new];
logger.interceptedTarget = aPath;
aPath = (UIBezierPath *)logger;
 
[aPath moveToPoint:CGPointMake(15.3f, 7.6f)];
 
/**
*   Result:
*   2013-04-04 10:20:53.719 svg_test[98065:c07] [path moveToPoint:{15.3, 7.6}]
**/

InvocationLogger.h

@interface InvocationLogger : NSObject
@property (strong, nonatomic) id interceptedTarget;
@end

InvocationLogger.m

@implementation InvocationLogger

- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
    return [_interceptedTarget methodSignatureForSelector:aSelector];
}

- (void)forwardInvocation:(NSInvocation *)anInvocation {
    
    CGPoint firstArg;
    [anInvocation getArgument:&firstArg atIndex:2];
    NSLog(@"[path %@%@]", NSStringFromSelector([anInvocation selector]), NSStringFromCGPoint(firstArg));
    
    [anInvocation invokeWithTarget:_interceptedTarget];
}

@end