#import "ViewController.h"

@interface ViewController ()<UIDynamicAnimatorDelegate,UICollisionBehaviorDelegate>

//动力效果的元素
@property(nonatomic,strong)UIImageView *ballItem;
@property (weak, nonatomic) IBOutlet UIImageView *bgView;
@property(nonatomic,strong)UIDynamicAnimator *animatior;
//碰撞到边境出现的图片
@property(nonatomic,strong)UIImageView *dungView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.bgView addSubview:self.ballItem];

}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    self.ballItem.center = [[touches anyObject] locationInView:self.view];
}

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    self.ballItem.center = [[touches anyObject] locationInView:self.view];
}

//拖动完之后让球掉落
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    NSLog(@"Y:%f",self.ballItem.frame.origin.y);
    [self gravityBehavior];
    [self collisionBehavior];
}
#pragma mark-------重力效果
- (void)gravityBehavior{
    //移除之前的效果
    [self.animatior removeAllBehaviors];
    UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc]initWithItems:@[self.ballItem]];
    gravityBehavior.gravityDirection = CGVectorMake(0.0, 1.0);
    //重力的方向
    //gravityBehavior.angle = 30*M_PI/180;
    //加速度 会影响下降速度
    gravityBehavior.magnitude = 1.5;
    //把重力效果添加到动力效果的操纵者上
    [self.animatior addBehavior:gravityBehavior];
}

#pragma mark-----检测碰撞的行为
- (void)collisionBehavior{
    
    UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc]initWithItems:@[self.ballItem]];
    //设置碰撞的样式(模式)
    collisionBehavior.collisionMode = UICollisionBehaviorModeEverything;
    //是否 以参照视图作为边界
    //collisionBehavior.translatesReferenceBoundsIntoBoundary = YES;
    
    //画圆
    //UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(20, 300, 300, 300) cornerRadius:150];
    //[collisionBehavior addBoundaryWithIdentifier:@"round" forPath:path];
    
    //画线
    [collisionBehavior addBoundaryWithIdentifier:@"line" fromPoint:CGPointMake(0, 680) toPoint:CGPointMake(414, 680)];
    collisionBehavior.collisionDelegate = self;
    [self.animatior addBehavior:collisionBehavior];
}

#pragma mark--------碰撞行为的代理方法
//元素之间的碰撞
- (void)collisionBehavior:(UICollisionBehavior *)behavior beganContactForItem:(id <UIDynamicItem>)item1 withItem:(id <UIDynamicItem>)item2 atPoint:(CGPoint)p{
    
}
- (void)collisionBehavior:(UICollisionBehavior *)behavior endedContactForItem:(id <UIDynamicItem>)item1 withItem:(id <UIDynamicItem>)item2{
    
}
//元素与边境之间的碰撞
- (void)collisionBehavior:(UICollisionBehavior*)behavior beganContactForItem:(id <UIDynamicItem>)item withBoundaryIdentifier:(nullable id <NSCopying>)identifier atPoint:(CGPoint)p{
    NSLog(@"开始接触边境");
    
    self.dungView.center = CGPointMake(p.x-20, p.y-20);
    //[self.dungView addSubview:self.ballItem];
    [self.bgView exchangeSubviewAtIndex:1 withSubviewAtIndex:0];
}
- (void)collisionBehavior:(UICollisionBehavior*)behavior endedContactForItem:(id <UIDynamicItem>)item withBoundaryIdentifier:(nullable id <NSCopying>)identifier{
    NSLog(@"结束接触边境");
    
    [behavior removeBoundaryWithIdentifier:@"line"];
    [self collisionBehavior];
}

#pragma mark--------UIDynamicAnimatorDelegate(动力效果操纵者)的两个代理方法
- (void)dynamicAnimatorWillResume:(UIDynamicAnimator *)animator{
    NSLog(@"开始");
}
- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator{
    NSLog(@"暂停");
}

- (UIImageView *)ballItem{
    if (_ballItem) {
        return _ballItem;
    }
    _ballItem = [[UIImageView alloc]initWithFrame:CGRectMake(100, 50, 50, 50)];
    _ballItem.image = [UIImage imageNamed:@"球"];
    return _ballItem;
}

- (UIDynamicAnimator *)animatior{
    if (_animatior) {
        return _animatior;
    }
    _animatior = [[UIDynamicAnimator alloc]initWithReferenceView:self.view];
    _animatior.delegate = self;
    return _animatior;
}

- (UIImageView *)dungView{
    if (_dungView) {
        return _dungView;
    }
    UIImage *image = [UIImage imageNamed:@"keng"];
    _dungView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 680, image.size.width/2.5, image.size.height/2.5)];
    _dungView.image = image;
    [self.bgView addSubview:_dungView];
    
    return _dungView;
}
@end