A great little helper for handling keyboard animations nicely. Just put this view at the bottom vertically of your views and it will move everything else up and down for you.

YMKeyboardLayoutHelperView.m

//
//  YMKeyboardLayoutHelperView.m
//  ios-chat
//
//  Created by Steven Hepting on 7/17/13.
//  Copyright (c) 2013 Yammer. All rights reserved.
//

#import "YMKeyboardLayoutHelperView.h"
#import "UIView+LayoutAdditions.h"

@interface YMKeyboardLayoutHelperView ()
@property (nonatomic) CGFloat desiredHeight;
@property (nonatomic) CGFloat duration;
@end

@implementation YMKeyboardLayoutHelperView

- (id)init
{
    self = [super init];
    if (self) {
        self.translatesAutoresizingMaskIntoConstraints = NO;
        
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
    }
    return self;
}

- (void)keyboardWillShow:(NSNotification *)notification
{
    // Save the height of keyboard and animation duration
    NSDictionary *userInfo = [notification userInfo];
    CGRect keyboardRect = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    self.desiredHeight = CGRectGetHeight(keyboardRect);
    self.duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
    
    [self animateSizeChange];
}

- (void)keyboardWillHide:(NSNotification *)notification
{
    self.desiredHeight = 0.0f;
    
    [self animateSizeChange];
}

- (CGSize)intrinsicContentSize
{
    return CGSizeMake(UIViewNoIntrinsicMetric, self.desiredHeight);
}

- (void)animateSizeChange
{
    [self invalidateIntrinsicContentSize];
    
    // Animate transition
    [UIView animateWithDuration:self.duration animations:^{
        [self.superview layoutIfNeeded];
    }];
}

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

@end

Updated the Gist to use intrinsicContentSize rather than constraints to make even simpler.

What is the #import "UIView+LayoutAdditions.h" for? I can't seem to get this to work :( I am placing a view in my storyboard and making this class the custom class. I moved your init code into my initFromCoder and it will not resize the view.

I was able to get it working correctly, works awesome when I use pure code but I'm having a lot of trouble with using it in the interface builder. :(

So elegant! One small bug I noticed when running on iPad and with rotation is that you need to convert the keyboard rect from screen coordinates (as delivered in the notification) to view coordinates. Otherwise width / height get mixed up. I'm using something like this:

CGRect screenRect = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
CGRect keyboardRect = [self convertRect:screenRect fromView:nil];

This piece of code has been integrated into a little more full-featured set of autolayout bits here: https://github.com/shepting/PSAutolayout

The rotation bug that mpvosseller mentioned is fixed in that version as well.