IOS CATransform3DMakeRotation need help with vectors

Question

I am trying to do a page flip animation and found this code on the internet. This works perfectly. It annimates a page turn from the right to the left, like a normal book. I want to modify the code to make it go from left to right, but I can not figure out how vectors & anchors work. Note these 2 lines I THINK need to be changed. Im just not sure to what...

viewToOpen.layer.anchorPoint = CGPointMake(0.0f, 0.5f);
            viewToOpen.center = CGPointMake(viewToOpen.center.x - viewToOpen.bounds.size.width/2.0f, viewToOpen.center.y);

CATransform3D endTransform = CATransform3DMakeRotation(3.141f/2.0f,
                                                               0.0f,
                                                               -1.0f,
                                                               0.0f);

Full function here:

- (void) pageOpenView:(UIView *)viewToOpen duration:(NSTimeInterval)duration {
    // Remove existing animations before stating new animation
    [viewToOpen.layer removeAllAnimations];

    // Make sure view is visible
    viewToOpen.hidden = NO;

    // disable the view so it’s not doing anythign while animating
    viewToOpen.userInteractionEnabled = NO;
    // Set the CALayer anchorPoint to the left edge and
    // translate the button to account for the new
    // anchorPoint. In case you want to reuse the animation
    // for this button, we only do the translation and
    // anchor point setting once.
    if (viewToOpen.layer.anchorPoint.x != 0.0f) {
        viewToOpen.layer.anchorPoint = CGPointMake(0.0f, 0.5f);
        viewToOpen.center = CGPointMake(viewToOpen.center.x - viewToOpen.bounds.size.width/2.0f, viewToOpen.center.y);
    }
    // create an animation to hold the page turning
    CABasicAnimation *transformAnimation = [CABasicAnimation animationWithKeyPath:@"transform"];
    transformAnimation.removedOnCompletion = NO;
    transformAnimation.duration = duration;
    transformAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    // start the animation from the current state
    transformAnimation.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];
    // this is the basic rotation by 90 degree along the y-axis
    CATransform3D endTransform = CATransform3DMakeRotation(3.141f/2.0f,
                                                           0.0f,
                                                           -1.0f,
                                                           0.0f);
    // these values control the 3D projection outlook
    endTransform.m34 = 0.001f;
    endTransform.m14 = -0.0015f;
    transformAnimation.toValue = [NSValue valueWithCATransform3D:endTransform];
    // Create an animation group to hold the rotation
    CAAnimationGroup *theGroup = [CAAnimationGroup animation];

    // Set self as the delegate to receive notification when the animation finishes
    theGroup.delegate = self;
    theGroup.duration = duration;
    // CAAnimation-objects support arbitrary Key-Value pairs, we add the UIView tag
    // to identify the animation later when it finishes
    [theGroup setValue:[NSNumber numberWithInt:viewToOpen.tag] forKey:@"viewToOpenTag"];
    // Here you could add other animations to the array
    theGroup.animations = [NSArray arrayWithObjects:transformAnimation, nil];
    theGroup.removedOnCompletion = NO;
    // Add the animation group to the layer
    [viewToOpen.layer addAnimation:theGroup forKey:@"flipViewOpen"];
}

Answer 1

It may depend on the layer and the view setup, but essentially

viewToOpen.layer.anchorPoint = CGPointMake(1.0f, 0.5f);
CATransform3D endTransform = CATransform3DMakeRotation(-M_PI/2.0f,0.0f,1.0f,0.0f)

---

The code in full will look like :

self.layer.anchorPoint = CGPointMake(1.0f, 0.5f);
self.layer.position = CGPointMake(self.layer.position.x + self.bounds.size.width/2.0f, self.layer.position.y);
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
animation.duration = 0.75f;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
CATransform3D tfm = CATransform3DMakeRotation(M_PI/2.0f, 0.0f, -1.0f, 0.0f);
tfm.m34 = 0.001f;
tfm.m14 = -0.0015f;
animation.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];
animation.toValue = [NSValue valueWithCATransform3D:tfm];
[self.layer addAnimation:animation forKey:@"flipUp"];