objective-c : make basic table view with custom background and jason data v.4

snippet.m

//make basic table view with custom background and jason data v.4
//Adding some menu dynamics and takes gesture velocity, add velocity to behavior

//DynamicSandwichViewController.m

@implementation DynamicSandwichViewController
{
    NSMutableArray* _views; //use this variable to keep track of the added views
    
    //Adding some menu dynamics
    UIGravityBehavior* _gravity;
    UIDynamicAnimator* _animator;
    CGPoint _previousTouchPoint;
    BOOL _draggingView;
}

#pragma mark - addRecipeAtOffset (add each recipe to the view)

- (UIView*)addRecipeAtOffset:(CGFloat)offset forSandwich:(NSDictionary*)sandwich {
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
 
 	...
    
    //adding gesture and dynamics
    
    // 1. add a gesture recognizer
    UIPanGestureRecognizer* pan = [[UIPanGestureRecognizer alloc]
                                   initWithTarget:self
                                   action:@selector(handlePan:)];
    [viewController.view addGestureRecognizer:pan];
    
    // 2. create a collision
    UICollisionBehavior* collision = [[UICollisionBehavior alloc]
                                      initWithItems:@[view]];
    [_animator addBehavior:collision];
    
    // 3. lower boundary, where the view will come to rest, based on the bottom edge of the current view location
    CGFloat boundary = view.frame.origin.y + view.frame.size.height+1;
    NSLog(@"boundary %f : view.frame.origin.y %f + view.frame.size.height %f", boundary, view.frame.origin.y, view.frame.size.height);
    
    CGPoint boundaryStart = CGPointMake(0.0, boundary);
    NSLog(@"boundaryStart = x %f, y %f", boundaryStart.x, boundaryStart.y);
    
    CGPoint boundaryEnd = CGPointMake(self.view.bounds.size.width,
                                      boundary);
    NSLog(@"boundaryEnd = x %f, y %f", self.view.bounds.size.width, boundary);
    
    [collision addBoundaryWithIdentifier:@1
                               fromPoint:boundaryStart
                                 toPoint:boundaryEnd];
    
    // 4. apply some gravity
    [_gravity addItem:view];
    
    
    //adds dynamic item behavior for each of the recipe views
    //It allows to change the physical properties of a dynamic item.
    UIDynamicItemBehavior* itemBehavior = [[UIDynamicItemBehavior alloc] initWithItems:@[view]];
    [_animator addBehavior:itemBehavior];

    
    return view;
}


#pragma mark - finds UIDynamicItemBehavior

// iterates over the behaviors until it finds the one with the correct type (UIDynamicItemBehavior)
- (UIDynamicItemBehavior*) itemBehaviourForView:(UIView*)view {
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    for (UIDynamicItemBehavior* behaviour in _animator.behaviors) {
    
        if (behaviour.class == [UIDynamicItemBehavior class]
            && [behaviour.items firstObject] == view) {
        
            return behaviour;
        }
}
    return nil;
}



- (void)handlePan:(UIPanGestureRecognizer*)gesture {
    
    CGPoint touchPoint = [gesture locationInView:self.view];
    UIView* draggedView = gesture.view;
    
    if (gesture.state == UIGestureRecognizerStateBegan) {
        // 1. was the pan initiated from the top of the recipe?
        CGPoint dragStartLocation = [gesture locationInView:draggedView];
        
        if (dragStartLocation.y < 200.0f) {
        _draggingView = YES;
        _previousTouchPoint = touchPoint;
        }
        
        //If a drag is in progress, use the difference in Y locations between the previous and the current touches
        //to offset the view’s center, making it move
    } else if (gesture.state == UIGestureRecognizerStateChanged && _draggingView) {
        // 2. handle dragging
        CGFloat yOffset = _previousTouchPoint.y - touchPoint.y;
        gesture.view.center = CGPointMake(draggedView.center.x,
                                          draggedView.center.y - yOffset);
        _previousTouchPoint = touchPoint;
        
    } else if (gesture.state == UIGestureRecognizerStateEnded && _draggingView) {
    	[self addVelocityToView:draggedView fromGesture:gesture];

        // 3. the gesture has ended
        // updateItemUsingCurrentState: asks a dynamic animator to read the current state of a dynamic item,
        // replacing the animator’s internal representation of the item’s state.
        [_animator updateItemUsingCurrentState:draggedView];
        _draggingView = NO; }
}


#pragma mark - addVelocityToView

//takes gesture velocity, removes X component, locates item behavior, adds velocity to behavior
- (void)addVelocityToView:(UIView*)view fromGesture:(UIPanGestureRecognizer*)gesture {
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    CGPoint vel = [gesture velocityInView:self.view];
    vel.x = 0;
    UIDynamicItemBehavior* behaviour = [self itemBehaviourForView:view];
    [behaviour addLinearVelocity:vel forItem:view];
}


#pragma mark - 뷰 라이프 사이클

- (void)viewDidLoad
{
    if (debug==1) {NSLog(@"Running %@ '%@'", self.class, NSStringFromSelector(_cmd));}
    
    ...
    
    //Adding some menu dynamics
    _animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
    _gravity = [[UIGravityBehavior alloc] init];
    [_animator addBehavior:_gravity];
    _gravity.magnitude = 4.0f; //making items fall more slowly than the default value of 1.0
    
    ...
}

@end