gistfile1.m

@interface UIView (LayoutConvenience)
- (NSLayoutConstraint *)constraintAligningAttribute:(NSLayoutAttribute)attr withView:(UIView *)otherView;
@end

@implementation UIView (LayoutConvenience)
- (NSLayoutConstraint *)constraintAligningAttribute:(NSLayoutAttribute)attr withView:(UIView *)otherView {
    return [NSLayoutConstraint constraintWithItem:self attribute:attr relatedBy:NSLayoutRelationEqual toItem:otherView attribute:attr multiplier:1.0 constant:0.0];
}
@end


@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UILabel *label1 = [[UILabel alloc] init];
    label1.text = @"Label 1";
    label1.textAlignment = NSTextAlignmentCenter;

    UILabel *label2 = [[UILabel alloc] init];
    label2.text = @"Label 2";
    label2.textAlignment = NSTextAlignmentCenter;
    label2.font = [UIFont systemFontOfSize:40];
    
    UIView *groupingView = [[UIView alloc] init];
    
    [[self view] addSubview:groupingView];
    [groupingView addSubview:label1];
    [groupingView addSubview:label2];
    
    id views = NSDictionaryOfVariableBindings(label1,label2,groupingView);
    for (UIView *view in [views allValues]) {
        [view setTranslatesAutoresizingMaskIntoConstraints:NO];
    }
    
    [[self view] addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[label1]|" options:0 metrics:nil views:views]];
    [[self view] addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[label2]|" options:0 metrics:nil views:views]];
    [[self view] addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[label1][label2]|" options:0 metrics:nil views:views]];
    
    [[self view] addConstraint:[[self view] constraintAligningAttribute:NSLayoutAttributeCenterX withView:groupingView]];
    [[self view] addConstraint:[[self view] constraintAligningAttribute:NSLayoutAttributeCenterY withView:groupingView]];
}

@end