Apple trees are not grown from seed. In order to get true to type trees, you have to obtain a rootstock (the crab apple) then graft a shoot of the tree you wish to propagate onto that rootstock. That's doing it the hard way, the easy way is to buy a tree which has been grafted by the nurseryman.
The reason that they are not grown from seed is that you have no clue as to what pollen the bee has brought to that flower. You could have a cooker crossed with a dessert or even crab apple which would taste awful.