Xcode Display Image if there is no image on Imageview

I need help to make somthink like this

IBOutlet UIImageView *imageview;
IBOutlet UIImageView *imageview2;

If(imageview have no image){
 SET this image @"x";
}else if(imageview2 have no image){
 Set this Image @"x";
}

And save and load the code With NSuserdefaults

PLS HELP!

THANKS!