Show HN: Flappy Block – Flappy Bird clone using the iOS7 Physics Engine

That is a great implementation. It seems like Nathan is using SpriteKit while my implementation uses UIDynamics. I just ran it and it seems to have collisions implemented. Mine doesn't have counters or anything extra on the screen yet, but the main challenge for me was playing with the physics engine.

is it possible to have both sprite kit and UIkitdynamics together

There are two physics engines in iOS 7.

SpriteKit - Contains a 2D physics engine similar to Box 2D but not as full featured (joints, rigid bodies, shapes, polygons). The whole engine is similar to Cocos2D but ships with iOS 7. A particle editor and texture atlas generator is now built-in to Xcode because of it.

UI Dynamics - Contains a set of constraints and joints which can be used to flip and throw views around the screen. Lots of API hooks for responding to / taking user interaction into account. This is used for effects like when you scroll the messages list (the message bubbles bounce and collide) or when you drop notification center down (it bounces).

Edit: from a brief look at the source code, this example uses the UIDynamicAnimator API, so it is simulated entirely with the UI dynamics stuff.

In iOS7, Apple introduced a new physics engine called UIDynamics. It's built natively into the OS which allows you to give any UIView on the screen physical properties such as Snap, Gravity, Collision, Attachments, and Pushing. Those properties, in turn, have settings like friction, density, gravitational pull, damping, elasticity, etc... The idea behind it was to make it so that you could create game style physics mechanics in any iOS application.

One example is the iOS7 notification center; If you drag it down and "slam" it to the bottom of the screen, it has some bounce. A second example is the Messages chats when scrolling quickly; You'll notice that as the swipe seed increases you get more space between peoples chat comments and they kind of slam together when you stop scrolling.

What I aimed to do here is take that same engine and use it to build FlappyBlock. So instead of having a loop that says:

    while () {                // Pipe is not on the left
      movePipeOnePixelLeft(); // Move Pipe one pixel over
      if (at the left) break; // If we hit the left, end loop
    }

Physics would say something like this:

    givePipeMassAndLocation();     // Give Pipe physical properties
    pushPipeLeftWithForceVector(); // Push pipe to left with force
    whenPipeHitsLeftWallRemove();  // Remove the pipe when it his the left

It's a different way of attacking the same problem using features many newer developers are not familiar with in iOS7.