If your getting edge cases, why don't you just write your own layoutSubviews method and avoid using constraints except for very basic things? It's relatively simple stuff to write, and is more performant than autolayout, since layoutSubviews is O(1)-ish while autolayout looks like it's O(n^2).

If you don't believe me, look at this blog article that measures it: http://floriankugler.com/blog/2013/4/21/auto-layout-performa...