DOViewController.m

//
//  DOViewController.m
//  LoginForm
//
//  Created by David Olesch on 4/1/14.
//  Copyright (c) 2014 David Olesch. All rights reserved.
//

#import "DOViewController.h"

@interface DOViewController ()
@property (strong, nonatomic) IBOutlet UITextField *usernameField;
@property (strong, nonatomic) IBOutlet UITextField *passwordField;
@property (strong, nonatomic) IBOutlet UIButton *loginButton;
@property (strong, nonatomic) UIDynamicAnimator *animator;
@end

@implementation DOViewController

- (IBAction)loginButtonTouched:(id)sender {
    self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
    NSArray *formElements = @[self.usernameField,self.passwordField,self.loginButton];
    
    UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc] initWithItems:formElements];
    collisionBehavior.translatesReferenceBoundsIntoBoundary = YES;
    [self.animator addBehavior:collisionBehavior];
    
    UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc] initWithItems:formElements];
    gravityBehavior.gravityDirection = CGVectorMake(0, 1);
    [self.animator addBehavior:gravityBehavior];
    
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        UISnapBehavior *snapBehavior = [[UISnapBehavior alloc] initWithItem:self.usernameField snapToPoint:CGPointMake(140, 100)];
        snapBehavior.damping = 1.f;
        [self.animator addBehavior:snapBehavior];
        [self.animator removeBehavior:gravityBehavior];
        
        UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc] initWithItems:formElements];
        gravityBehavior.gravityDirection = CGVectorMake(0, -1);
        [self.animator addBehavior:gravityBehavior];
    });
    
}

@end