Example of using auto layout to make a container view as tall as its tallest subview, but no taller. For http://stackoverflow.com/q/17117799/77567 .

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController {
    UIView *containerView;
    NSArray *subviews;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.translatesAutoresizingMaskIntoConstraints = NO;
    [self makeContainerView];
    [self makeSubviews];
}

- (void)makeContainerView {
    containerView = [[UIView alloc] init];
    containerView.translatesAutoresizingMaskIntoConstraints = NO;
    containerView.backgroundColor = [UIColor colorWithHue:0.2 saturation:0.1 brightness:0.9 alpha:1];
    [self.view addSubview:containerView];

    // Horizontal constraints
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[containerView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(containerView)]];

    // Vertically center the container view in my view
    [self.view addConstraint:[NSLayoutConstraint constraintWithItem:containerView attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeBottom multiplier:0.5 constant:0]];

    // Ask the container to have height 0, but give the constraint a low priority.
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:containerView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:0 constant:0];
    constraint.priority = UILayoutPriorityDefaultLow;
    [containerView addConstraint:constraint];
}

- (void)makeSubviews {
    UIView *subview0 = [self makeSubviewWithFrame:CGRectMake(20, 0, 80, 50)];
    UIView *subview1 = [self makeSubviewWithFrame:CGRectMake(120, 0, 80, 100)];
    UIView *subview2 = [self makeSubviewWithFrame:CGRectMake(220, 0, 80, 80)];
    subviews = @[ subview0, subview1, subview2 ];
}

- (UIView *)makeSubviewWithFrame:(CGRect)frame {
    UIView *subview = [[UIView alloc] init];
    subview.translatesAutoresizingMaskIntoConstraints = NO;
    subview.backgroundColor = [UIColor colorWithHue:0.5 saturation:0.1 brightness:0.9 alpha:1];
    [containerView addSubview:subview];

    // Set the subview's size and X position from the frame.  The Y position will be determined by auto layout.
    [subview addConstraint:[NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:0 constant:frame.size.width]];
    [subview addConstraint:[NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:0 constant:frame.size.height]];
    [containerView addConstraint:[NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:containerView attribute:NSLayoutAttributeLeading multiplier:1 constant:frame.origin.x]];

    // Pin the bottom of subview to the bottom of containerView.
    [containerView addConstraint:[NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:containerView attribute:NSLayoutAttributeBottom multiplier:1 constant:0]];

    // Constrain the container view to be at least as tall as the subview.
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:containerView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:subview attribute:NSLayoutAttributeHeight multiplier:1 constant:0];
    constraint.priority = UILayoutPriorityRequired;
    [containerView addConstraint:constraint];

    return subview;
}

@end