UIImageView setImage doesn't work with presentModelViewController?

The first thing to look for is whether you're sending the setImage message to the UIImageView instance you expect. Use NSLog to check for a nil pointer in the same place you're trying to set the image. Obj-C loves to make newbies crazy by sending messages to nil pointers without any warning or other problem. If the pointer is nil, double check the IBOutlet connection to the UIImageView in IB.

If the pointer isn't nil, make sure you didn't reset it someplace in your code. It's easy to get confused and alloc another instance of UIImageView which would then be happy to accept the image message while the view which is actually visible remains unchanged. You might try sending a different message to the view, e.g. resetting the frame, as a sanity check.

When you're convinced the message is going to the right view, check the line that sends the message; it should look something like this:

[[imageView setImage:[UIImage imageNamed:@"Picture.jpg"]];