Apple is one of my favorites. It is one of the hardest domestic lumbers. It turns awesome, carves perfect and smells the best! It is relatively stable once it is dry, but not as stable as maple or oak. It really likes to warp, twist and crack when drying. You can easily cut a 1" thick board and when it dry's it could twist into a pretzel! I recommend the boards be cut at least 1.25 thick. Sticker them and put lots of cinder blocks on top. Air drying with lots of time is probably the best action to take. Paint the ends, mark the start date and wait a year. After one year, put some 6x6's on the cement floor. Weigh a board and write the weight on that board. Sticker stack the pile on the 6x6's. Place a dehimidifier beside the stack. Wrap the bundle with plastic and tape it around the dehimidifier so the front of the dehumidifier is outside the bundle and run a hose outside to get rid of the water. Wait 2 weeks then re-weigh that board. Put back in for a week and the re-weigh again. Keep doing this until the weight does not change. Patience is a virtue, especially with this lumber.
Typical apple is just as described above, skin tones on the outside, coffee on the inside. Crab apple, which is my preference, is skin tones almost all the way through. I use it alot for carving people. When it oxidizes it really captures the essence of skin. The wood is quite valuable. I just had a crab apple tree sawed up and sticker stacked it yesterday too. Very exciting. My crab apple had a ton of crotches and I had it all slabbed with the bark still on straight through all the crotches, just slab cut that baby and when you get to the heart pieces, cut those out and pitch them..pardon the pun. If you don't cut out the pitch, you'll be sorry. It will crack super bad and the cracks will spread into the good wood.