In a pressure cooker coat the bottom with olive oil. Add the chopped onions and saute for 2-3 minutes.
Add salt, pepper, cumin, garlic, and saffron, and turmeric.
Place the chicken on top and mix so that it is coated with the spices and oil.
Cover chicken with water and place the lid tightly onto the pressure cooker.
Allow to cook on low to medium heat for 45 minutes - 1 hours Remove from heat. You should check to make sure there is enough water about 1/2 way through. You can do this by picking up the pressure cooker by the lid and swirling the contents. If it seems there is still water you're ok, if not release pressure valve and remove cover, then add more water.
After approx 1 hour, remove the lid, and add the smen. Mix well. Also add the olives at this time. Continue cooking with the lid off until a thick sauce has been created. This should not be watery but have some consistency to it. The chicken should be almost falling off the bone.
Turn out the meat and olives to a serving plate. In Morocco this is eaten from a common plate using flat bread as utensils. If you feel adventurous go for it! If not a fork does the trick too!