FlipFlip-Flipboard-Prototype

A barebones control similar to Flipboard's page flipping animation.

How to Use

Simply insert your viewControllers into self.orderedViewArray. The demo just uses images, but it supports view controller views with live UI elements.

Key Learnings and Decisions

• Most of the magic happens with this single piece of code:

-(void)applyRotation:(CGFloat)degrees toView:(UIView*)view
{
    CATransform3D transform = CATransform3DIdentity;
    transform.m34 = -1.0 / 4000;
    transform = CATransform3DRotate(transform, degrees *( M_PI / 180.0f), 1.0f,0.0f, 0.0f);
    view.layer.transform = transform;
}

• This rotates a UIView's transform in 3D, allowing it to look like its flipping over.
• So I made a subclass called FlippableBlockView which is essentially a UIView with some properties.
• At minimum there are 4 FlippableBlockView's on screen at any given time. 2 for the current page, 1 behind top, 1 behind bottom.
• After a successful flip, regenerate previews for the previous/next page (behind top and behind bottom).

Refactor

It works well enough, but some things I would have liked to fix/improve are:

• Shadows: It would be way better to put the shadow alpha code in: -(void)applyRotation:(CGFloat)degrees toView:(UIView*)view
• Finer touch: it gets a bit touchy when you try to swipe fast, also the animation durations are fixed in time.
• Page limits: Rather than stop allowing the page to turn when you hit either 0 or self.orderdViewArray.count, it would be nicer to allow some degree of flipping and show a black view behind.

###Helpful sources I used:
I got started with Stephen Zaharuk's proof of concept: http://www.infragistics.com/community/blogs/stevez/archive/2014/04/08/ios-objective-c-how-to-simulate-a-flipboard-style-page-turn.aspx