I have this problem for several months already and I can't fix it so far.
I have an UIViewTableCell with its xib. I changed the xib with XCode IB several times, something I do frequently without issues with a lot of xibs. Suddenly old versions of the UIView start appearing... Ok, I rebuilt, deleted all obj and bin folders, tried to turn off incremental builds, link all, updated Xamarin Studio and iOS, etc. but nothing... So it's already more than 2 months with the old UIView, but I now I really need to change it. I deleted the content UIViews and put everything again and it worked, until I worked with another xib and again the old version showing up... After few tests, when I open the xib source code I don't change anything but save it, the new UIView appears, but when I do the same with another UIView, the old UIView of the first one comes back. I think that an old xib is cached and makes show the old version... or whatever it is it shouldn't happen and it's pretty annoying. It happens in simulator and phone, in debug or release.
Hope someone can help me here. I'm working with Xamarin.iOS - Xamarin Studio on Mac. Thanks.