PARMANOIR

Animating squares, this looks like that :

You're expecting layers to smoothly move to their new positions, but they're fading instead. Turns out it's because creation and animation are done in the same transaction. You're telling CA to create and animate, CA then tries to move from N objects to N+1 objects smoothly. It does that with a fade.

The fix

Do it in two transactions. Use a zero duration transaction for creating your layers, then animate them.

// Creation transaction, zero duration
[CATransaction begin];
[CATransaction setValue:[NSNumber numberWithFloat:0] forKey:kCATransactionAnimationDuration];
[self addRect:NSMakeRect(0, 50, 90, 100)];
[CATransaction commit];

// Animation transaction, whatever duration you want
[CATransaction begin];
[CATransaction setValue:[NSNumber numberWithFloat:duration] forKey:kCATransactionAnimationDuration];
[self animateLayers];
[CATransaction commit];

You'll then see what you expected : smooth animation to the new positions.

Sample Code

CoreAnimationPhantomFade.zip