iOS4, XCode linking problems

Question

I'm having problems using the QuartzCore framework. Here's the code that's trying to run:

#import <QuartzCore/QuartzCore.h>

CATransition *animation = [CATransition animation];
[animation setDuration:0.5];
[animation setType:kCATransitionPush];
[animation setSubtype:kCATransitionFromLeft];
[animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
[[self.view layer] addAnimation:animation forKey:@"SwitchToView1"];

I get the following errors when compiling:

ld: warning: in ./QuartzCore.framework/QuartzCore, missing required architecture i386 in file
        "_kCATransitionPush", referenced from: _kCATransitionPush$non_lazy_ptr in ThreadViewController.o
    (maybe you meant: _kCATransitionPush$non_lazy_ptr)

And similar errors for each constant.

This very question has been asked before but the solutions for it don't work for me. The standard answer is to make sure that the QuartzCore framework is added to the project, which it is. (I've added it in the ways that are described to others asking this) Another thought is that it is linking against the device libraries instead of the simulator libraries, which it isn't either. Double checked both several times.

Anyone know the cause of this?

I'm using XCode 3.2.3, and iOS 4.0.