I know some pears do not fruit every year, and am wondering if it might also be true of certain apple varieties. The other possibilities are - if you may have pruned it back very hard, that means fruit will come next year, or that the blossom was damaged or interrupted in some way. Some more detail would be helpful, to find out why, and can you post a photo?
Do you know what sort of apple it is, and how old is the tree, to your knowledge?

Frost at the wrong time, strong winds at the wrong time, and even drought at the wrong time can damage flowers before they produce fruit.