NSView *superview = …; // Reference to the view that will contain the box
// for instance, [window contentView]
NSUInteger resizeAllMask = (NSViewWidthSizable
| NSViewHeightSizable
| NSViewMinXMargin
| NSViewMaxXMargin
| NSViewMinYMargin
| NSViewMaxYMargin);
// This is the box. We use an autoresizing mask so that it occupies
// the entire superview
NSBox *box = [[NSBox alloc] initWithFrame:[superview bounds]];
[box setAutoresizingMask:resizeAllMask];
[box setBoxType:NSBoxPrimary];
[box setBorderType:NSBezelBorder];
[box setTitle:@"This is a box"];
// This is the box' content view. It represents the box contents.
// By default, a box autoresizes its content view so that it occupies
// the entire box
NSView *boxContentView = [[NSView alloc] initWithFrame:NSZeroRect];
[box setContentView:boxContentView];
// For example, we add a text field to the box' content view
NSRect textRect = {{0,0}, {100,20}};
NSTextField *textField = [[NSTextField alloc] initWithFrame:textRect];
[textField setStringValue:@"Hey there"];
[boxContentView addSubview:textField];
[superview addSubview:box];