CatAwakenNibSnippet.m

-(void)awakeFromNib{
    
    NSDictionary * catImageReferences = NSDictionaryOfVariableBindings(_topLeftCat, _topRightCat, _bottomLeftCat, _bottomRightCat);
    NSDictionary * catMetrics = @{ @"catImageWidth" : [NSNumber numberWithFloat:150.0],
                                   @"catImageHeight" : [NSNumber numberWithFloat:120.0]
                                   };
    
    NSArray * topRowOfCats = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[_topLeftCat(==catImageWidth)]-10-[_topRightCat]-|"
                                                                     options:0
                                                                     metrics:catMetrics
                                                                       views:catImageReferences];