Small class (Alert View) we made during third week at ironhack bootcamp using UIKit Dynamics. http://victorbaro.com/2015/02/custom-dynamic-alertview/

CustomDynamicAlertView

//
//  CustomDynamicAlertView.h
//  Week3_inclass
//
//  Created by Victor Baro on 18/02/2015.
//  Copyright (c) 2015 Produkt. All rights reserved.
//

#import <UIKit/UIKit.h>

@protocol CustomDynamicAlertViewDelegate <NSObject>
- (void)dismissAnimationFinished;
@end

@interface CustomDynamicAlertView : UIView
@property (nonatomic, strong) NSString *mainText;
@property (nonatomic, strong) NSString *dismissButtonText;
@property (nonatomic, weak) id<CustomDynamicAlertViewDelegate> delegate;
- (instancetype)initWithFrame:(CGRect)frame
                     mainText:(NSString *)mainText
            dismissButtonText:(NSString *)dismissButtonText;
@end



//
//  CustomDynamicAlertView.m
//  Week3_inclass
//
//  Created by Victor Baro on 18/02/2015.
//  Copyright (c) 2015 Produkt. All rights reserved.
//

#import "CustomDynamicAlertView.h"

@interface CustomDynamicAlertView () <UICollisionBehaviorDelegate>
@property (nonatomic,weak) UIView *alertView;
@property (nonatomic, weak) UILabel *mainTextLabel;
@property (nonatomic, weak) UIButton *dismissButton;
@property (nonatomic, strong) UIDynamicAnimator *mainAnimator;
@property (nonatomic, strong) UISnapBehavior *snapBehavior;

@end

static CGFloat const buttonHeight = 50;
static CGFloat const alertWidth = 250;
static CGFloat const alertHeight = 150;
static CGFloat const mainTextMargin = 15;
static NSString const *kBoundaryID = @"outsideBoundary";


@implementation CustomDynamicAlertView

- (instancetype)initWithFrame:(CGRect)frame {
    return [self initWithFrame:frame mainText:@"Add a main text to show here as a main text." dismissButtonText:@"Dismiss"];
}
- (instancetype)initWithFrame:(CGRect)frame mainText:(NSString *)mainText dismissButtonText:(NSString *)dismissButtonText {
    self = [super initWithFrame:frame];
    if (self) {
        _mainText = mainText;
        _dismissButtonText = dismissButtonText;
        [self initializeCustomProperties];
    }
    return self;
}
- (void)initializeCustomProperties {
    self.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.6];
    [self createAlertView];
    [self initializeDynamics];
}

- (void)createAlertView {
    UIView *alertView = [[UIView alloc]initWithFrame:CGRectMake(CGRectGetWidth(self.bounds)/2 - alertWidth/2,
                                                                -400,
                                                                alertWidth,
                                                                alertHeight)];
    alertView.backgroundColor = [UIColor whiteColor];
    alertView.clipsToBounds = YES;
    alertView.layer.cornerRadius = 10;
    [self addSubview:alertView];
    self.alertView = alertView;
    
    UILabel *mainTextLabel = [[UILabel alloc]initWithFrame:CGRectMake(mainTextMargin, 0, alertWidth - mainTextMargin*2, alertHeight - buttonHeight)];
    mainTextLabel.text = self.mainText;
    mainTextLabel.backgroundColor = [UIColor clearColor];
    mainTextLabel.textColor = [UIColor colorWithWhite:0.05 alpha:1.0];
    mainTextLabel.font = [UIFont systemFontOfSize:14];
    mainTextLabel.numberOfLines = 0;
    mainTextLabel.textAlignment  = NSTextAlignmentCenter;
    [alertView addSubview:mainTextLabel];
    self.mainTextLabel = mainTextLabel;
    
    UIButton *dismissButton = [UIButton buttonWithType:UIButtonTypeSystem];
    dismissButton.frame = CGRectMake(0, alertHeight - buttonHeight, alertWidth, buttonHeight);
    [dismissButton setTitle:self.dismissButtonText forState:UIControlStateNormal];
    [dismissButton addTarget:self action:@selector(dismissButtonPressed) forControlEvents:UIControlEventTouchUpInside];
    dismissButton.backgroundColor = [UIColor redColor];
    dismissButton.tintColor = [UIColor whiteColor];
    [alertView addSubview:dismissButton];
    self.dismissButton = dismissButton;
}

- (void)initializeDynamics {
    self.mainAnimator = [[UIDynamicAnimator alloc]initWithReferenceView:self];
    self.snapBehavior = [[UISnapBehavior alloc]initWithItem:self.alertView snapToPoint:CGPointMake(CGRectGetWidth(self.bounds)/2, CGRectGetHeight(self.bounds)/2)];
    [self.mainAnimator addBehavior:self.snapBehavior];
}

- (void)dismissButtonPressed {
    [self.mainAnimator removeAllBehaviors];
    UIGravityBehavior *gravityB = [[UIGravityBehavior alloc]initWithItems:@[self.alertView]];
    gravityB.magnitude = 4.0;
    [self.mainAnimator addBehavior:gravityB];
    
    UIPushBehavior *pushB = [[UIPushBehavior alloc]initWithItems:@[self.alertView] mode:UIPushBehaviorModeInstantaneous];
    [pushB setAngle:-(M_PI_2 * 0.8) magnitude:25.0];
    [self.mainAnimator addBehavior:pushB];
    
    UICollisionBehavior *collisionB = [[UICollisionBehavior alloc]initWithItems:@[self.alertView]];
    
    [collisionB addBoundaryWithIdentifier:kBoundaryID
                                fromPoint:CGPointMake(0, CGRectGetHeight(self.bounds) + alertHeight)
                                  toPoint:CGPointMake(CGRectGetWidth(self.bounds) * 2, CGRectGetHeight(self.bounds) + alertHeight)];
    
    
    collisionB.collisionDelegate = self;
    [self.mainAnimator addBehavior:collisionB];
}

#pragma mark -  CollisionDelegate

- (void)collisionBehavior:(UICollisionBehavior *)behavior beganContactForItem:(id<UIDynamicItem>)item withBoundaryIdentifier:(id<NSCopying>)identifier atPoint:(CGPoint)p {
    if (identifier == kBoundaryID) {
        [self.delegate dismissAnimationFinished];
        [self removeFromSuperview];
    }
}


#pragma mark -  setters
- (void)setMainText:(NSString *)mainText {
    _mainText = mainText;
    self.mainTextLabel.text = mainText;
}
- (void)setDismissButtonText:(NSString *)dismissButtonText {
    _dismissButtonText = dismissButtonText;
    [self.dismissButton setTitle:dismissButtonText forState:UIControlStateNormal];
}
@end