Notification views

RootVC.h

@interface RootVC : UIViewController <UIDynamicAnimatorDelegate>

@property (strong, nonatomic) UIDynamicAnimator *animator;
@property (strong, nonatomic) UIView *noticeView;

RootVC.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
    self.animator.delegate = self;
}

- (void)saveArticle:(id)sender
{
    // initialize then add the noticeView
    
    self.noticeView = [[UIView alloc] init];
    
    // set the noticeView.frame off screen
    self.noticeView.frame = CGRectMake(0, -20, 320, 30);
    self.noticeView.noticeLabel.text = @"Saved!";
    [self.scrollView addSubview:self.noticeView];
    
    
    // add a snap behavior - the snap point being the centre of where you want the view to be.
    UISnapBehavior *snapBehavior = [[UISnapBehavior alloc] initWithItem:self.noticeView snapToPoint:CGPointMake(160, 15)];
    // make it look sexy
    snapBehavior.damping = 0.3;
    
    [self.animator addBehavior:snapBehavior];
}

// called when the noticeView comes to rest:
// pushes off screen to finish
- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator
{
    [self.animator removeAllBehaviors];
    
    UIPushBehavior *removePush = [[UIPushBehavior alloc] initWithItems:@[self.noticeView] mode:UIPushBehaviorModeInstantaneous];
    removePush.pushDirection = CGVectorMake(9,0);
    
    [self.animator addBehavior:pushBehavior];
    
    removePush.action = ^{
        if(!CGRectIntersectsRect(self.view.frame, self.noticeView.frame)) {
            [self.animator removeBehavior:pushBehavior];
            [self.noticeView removeFromSuperView];
        }
    }
}

// or the cooler version, falling down with a bit of an angle:
- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator
{
    if([self.noticeView isDescendantOfView:self.view]) {
        [self.noticeView removeFromSuperview];
        [self.animator removeAllBehaviors];
    }
    
    [self.animator removeAllBehaviors];
    
    UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc[ initWithItem:self.noticeView];
    gravityBehavior.gravityDirection = CGVectorMake(0,5);
    [self.animator addBehavior:gravityBehavior];
    
    UIDynamicItemBehavior *dynamicBehavior = [[UIDynamicItemBehavior alloc] initWithItems:@[self.noticeView]];
    [dynamicBehavior addAngularVelocity:(M_PI / 2) forItem:self.noticeView];
    
    [self.animator addBehavior:dynamicBehavior];
    
    gravityBehavior.action = ^{
        if(!CGRectIntersectsRect(self.view.frame, self.noticeView.frame)) {
            [self.animator removeBehavior:gravityBehavior];
            [self.noticeView removeFromSuperView];
        }
    }
}