What is happening right now?

A few things to consider:

• only check collision between two object in one class -- not in both (I would put it all in the Mario class);
• only check collision immediately after each move of the actor;
• keep horizontal and vertical movement code separate (knowing which move caused a collision will tell you the orientation of the colliding actors);
• you may want to dispense with the array of enemies in your world class; I doubt very much that there is a need for it

Please give your reason for the array if you feel you need it. To determine orientation, you will also need the sign of the speed along the axis moved. For example if moving vertically ("falling"), if vSpeed is negative then a collision will be a upward moving head-bump and, if positive then it will be a landing atop of the actor.

So, basically, you want something like this: <Code Omitted>

Thank you so much, I was finally able to enter the app!

Thanks very much danpost, sorry for the late reply.

What did you try?