Using dot syntax for non-@property properties?

FROM : Joshua Emmons
DATE : Wed Nov 07 02:30:45 2007

One of the dot syntax "Usage Summaries" from "The Objective-C 2.0 
Programming Language" is:

xOrigin = aView.bounds.origin.x;

This leads me to believe that I can replace the following code:

-(void)viewClicked:(id)sender{
    NSSize size = [sender bounds].size;
    size.height *= 2;
    [[sender animator] setBoundsSize:size];
}

with something like:

-(void)viewClicked:(id)sender{
    NSSize size = sender.bounds.size;
    size.height *= 2;
    sender.animator.boundsSize = size;
}

However, when I do so, I get errors like "request for member 'bounds' 
in something not a structure or a union". It sounds to me like the 
compiler has no idea what's going on with the dot there. Or, at least, 
it's definitely not [sender bounds], which is what I would have 
expected. What am I overlooking here?

Many thanks,
-Joshua Emmons