#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    aSphere = [[Sphere alloc]initWithFrame:CGRectMake(100, 100, 50, 50)];
    [aSphere setBackgroundColor:[UIColor redColor]];
    [aSphere setUserInteractionEnabled:YES];
    [[aSphere layer]setCornerRadius:[aSphere bounds].size.width / 2];
    [[self view]addSubview:aSphere];

    bSphere = [[Sphere alloc]initWithFrame:CGRectMake(220, 200, 50, 50)];
    [bSphere setBackgroundColor:[UIColor greenColor]];
    [bSphere setUserInteractionEnabled:YES];
    [[bSphere layer]setCornerRadius:[bSphere bounds].size.width / 2];
    [[self view]addSubview:bSphere];

    cSphere = [[Sphere alloc]initWithFrame:CGRectMake(380, 300, 50, 50)];
    [cSphere setBackgroundColor:[UIColor blueColor]];
    [cSphere setUserInteractionEnabled:YES];
    [[cSphere layer]setCornerRadius:[cSphere bounds].size.width / 2];
    [[self view]addSubview:cSphere];

    dSphere = [[Sphere alloc]initWithFrame:CGRectMake(self.view.center.x, self.view.center.y, 50, 50)];
    [dSphere setCenter:self.view.center];
    [dSphere setBackgroundColor:[UIColor orangeColor]];
    [dSphere setUserInteractionEnabled:YES];
    [[dSphere layer]setCornerRadius:[dSphere bounds].size.width / 2];
    [[self view]addSubview:dSphere];

    UITapGestureRecognizer *aTap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tap:)];
    [aTap setNumberOfTapsRequired:1];

    [aSphere addGestureRecognizer:aTap];

    animator = [[UIDynamicAnimator alloc]initWithReferenceView:[self view]];
    [animator setDelegate:self];
    gravity = [[UIGravityBehavior alloc]init];
    [animator addBehavior:gravity];

    collision = [[UICollisionBehavior alloc]initWithItems:@[aSphere, bSphere, cSphere, dSphere]];
    [collision setTranslatesReferenceBoundsIntoBoundary:YES];
    [animator addBehavior:collision];

    UIDynamicItemBehavior *aSphereBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[aSphere]];
    [aSphereBehavior setElasticity:0.6];
    [animator addBehavior:aSphereBehavior];

    UIDynamicItemBehavior *bSphereBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[bSphere]];
    [bSphereBehavior setElasticity:0.3];
    [animator addBehavior:bSphereBehavior];

    UIDynamicItemBehavior *cSphereBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[cSphere]];
    [cSphereBehavior setElasticity:0.9];
    [animator addBehavior:cSphereBehavior];

    UIDynamicItemBehavior *dSphereBehavior = [[UIDynamicItemBehavior alloc]initWithItems:@[dSphere]];
    [dSphereBehavior setElasticity:0.2];
    [animator addBehavior:dSphereBehavior];
}

- (void)tap:(UITapGestureRecognizer *)tapRecog
{
    Sphere *view = (Sphere *)[tapRecog view];

    if (snap) {
        [animator removeBehavior:snap];
    }

    CGPoint point = self.view.center;

    UIAttachmentBehavior *attachment = [[UIAttachmentBehavior alloc]initWithItem:view attachedToAnchor:view.center];
    [animator addBehavior:attachment];
    attachment.frequency = 10.0;
    attachment.damping = 50.0;
    attachment.anchorPoint = point;

    UIDynamicItemBehavior *resistance = [[UIDynamicItemBehavior alloc]initWithItems:@[view]];
    resistance.resistance = 50;
    [animator addBehavior:resistance];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

@end