UILabel's layer doesn't update color while animating

I am animating a UILabel to 'evaporate' off the screen using CATransition.
I want the label text to turn green, and move off the screen.

The following code does 'evaporate' the label fine, but doesn't change its colour before animating:

CATransition *transition = [CATransition animation];
transition.beginTime = CACurrentMediaTime();
transition.duration = 0.4;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromTop;

[self.displayLabel.layer addAnimation:transition forKey:@"evaporate"];

self.displayLabel.textColor = [self greenColor];
self.displayLabel.text = @" ";

Calling setNeedsDisplay on the label doesn't work.
Can't use a CABasicAnimation because the label text is changing.

What am I doing wrong and how do I fix it?

You basically want nested animations or, in a sense, looking for a completion block type thing.
The closest I can think of achieving this is by using the CATransition delegate

Example:

-(IBAction)btnTest:(UIButton *)sender
{
    //[1] Animate text color change

    CATransition *animation = [CATransition animation];
    [animation setDelegate:self]; //important
    [animation setRemovedOnCompletion:YES]; //better to remove the animation
    [animation setBeginTime:CACurrentMediaTime()]; //not really needed
    [animation setDuration:0.4];
    [animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault]];
    [animation setType:kCATransitionFade];

    //you can specify any key name or keep it nil. doesn't make a difference
    [self.displayLabel.layer addAnimation:animation forKey:@"changeTextColor"];
    [self.displayLabel setTextColor:[UIColor greenColor]];
}

#pragma mark - CATransition Delegate
-(void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    //[2] Animate text sublayer

    /*
     The following CATransition should not set a delegate
     otherwise this animation will loop continously
    */

    CATransition *animation = [CATransition animation];
    [animation setRemovedOnCompletion:YES]; //better to remove the animation
    [animation setBeginTime:CACurrentMediaTime()]; //not really needed
    [animation setDuration:0.4];
    [animation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault]];
    [animation setType:kCATransitionPush];
    [animation setSubtype:kCATransitionFromTop];

    //you can specify any key name or keep it nil. doesn't make a difference
    [self.displayLabel.layer addAnimation:animation forKey:@"changeText"];
    [self.displayLabel setText:@" "];
}