For those working with limited space, there are a few options. First, you might select a dwarf or semi-dwarf variety of the fruit tree. Dwarf and semi-dwarf trees have the dual benefit of not only taking up less space, but producing fruit much quicker than standard trees. (A full-size tree often takes up to five years before producing any fruit).  Second, you can choose to train your tree into a cordon or espalier (where the trunk and/or branches are trained to grow along wire fence supports).  Thirdly, you might choose to pot your tree, rather than plant it in the ground. A potted tree will require more feeding and watering, but allows for more flexibility and can be moved indoors during inclement weather. This is beneficial (and might be necessary) if you’re growing citrus or other tropical fruit.  Finally, if your tree requires other nearby trees for pollination but you lack sufficient space for an orchard, consider coordinating with your neighbors; this way each of you only needs to care for one tree, but both benefit from pollination and you can swap different fruit varieties.

Title: The City Homesteader: Self-Sufficiency on Any Square Footage
Author: Scott Meyer 
Publisher: Running Press, 2011      
Description: Provides brief overviews of various berries and fruit trees, including instructions for planting and pruning. Ch. 1, "Growing Your Own", pp. 34-36, Small Space Fruit.