Spin Segue using CABasicAnimation

NASpinSegue.m

#import "NASpinSegue.h"
#import <QuartzCore/QuartzCore.h>

#define SPINS              3.0f
#define DURATION           0.5f
#define TRANSITION_OUT_KEY @"transition out"
#define TRANSITION_IN_KEY  @"transition in"
#define TRANSITION_IDENT   @"transition type"

@implementation NASpinSegue

-(CALayer *)sourceLayer{
    UIViewController *sourceViewController = (UIViewController *)self.sourceViewController;
    return sourceViewController.view.layer;
}

-(CALayer *)destinationLayer{
    UIViewController *destinationViewController = (UIViewController *)self.destinationViewController;
    return destinationViewController.view.layer;
}

- (void)perform{
    
    CABasicAnimation *rotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    rotation.fromValue = [NSNumber numberWithFloat:0.0f];
    rotation.toValue   = [NSNumber numberWithFloat:M_PI * SPINS];
    
    CABasicAnimation *scaleDown = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
    scaleDown.fromValue = [NSNumber numberWithFloat:1.0f];
    scaleDown.toValue   = [NSNumber numberWithFloat:0.0f];
    
    CABasicAnimation *fadeOut = [CABasicAnimation animationWithKeyPath:@"opacity"];
    fadeOut.fromValue = [NSNumber numberWithFloat:1.0f];
    fadeOut.toValue   = [NSNumber numberWithFloat:0.0f];
    
    CAAnimationGroup *transitionOut = [CAAnimationGroup animation];
    transitionOut.animations          = [NSArray arrayWithObjects:rotation, scaleDown, fadeOut, nil];
    transitionOut.duration            = DURATION;
    transitionOut.delegate            = self;
    transitionOut.removedOnCompletion = NO;
    transitionOut.fillMode            = kCAFillModeForwards;
    [transitionOut setValue:TRANSITION_OUT_KEY forKey:TRANSITION_IDENT];

    [self.sourceLayer addAnimation:transitionOut forKey:TRANSITION_OUT_KEY];
}

- (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag{
    
    NSString *type = [theAnimation valueForKey:TRANSITION_IDENT];
    
    if ([type isEqualToString:TRANSITION_OUT_KEY]) {

        CABasicAnimation *rotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
        rotation.fromValue = [NSNumber numberWithFloat:0.0f];
        rotation.toValue   = [NSNumber numberWithFloat:M_PI * SPINS];

        CABasicAnimation *scaleUp = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
        scaleUp.fromValue = [NSNumber numberWithFloat:0.0f];
        scaleUp.toValue   = [NSNumber numberWithFloat:1.0f];
        
        CAAnimationGroup *transitionIn = [CAAnimationGroup animation];
        transitionIn.animations = [NSArray arrayWithObjects:rotation, scaleUp, nil];
        transitionIn.duration   = DURATION;
        transitionIn.delegate   = self;
        [transitionIn setValue:TRANSITION_IN_KEY forKey:TRANSITION_IDENT];
        
        [self.sourceViewController presentModalViewController:self.destinationViewController animated:NO];
        [self.destinationLayer addAnimation:transitionIn forKey:TRANSITION_IN_KEY];
        return;
    }
    
    if ([type isEqualToString:TRANSITION_IN_KEY]) {
        [self.sourceLayer removeAnimationForKey:TRANSITION_OUT_KEY];
    }
    
}