【iOS】UIDynamicAnimator动画

创建动画

UIDynamicAnimator *animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

协议代理

@protocol UIDynamicAnimatorDelegate <NSObject>

@optional
- (void)dynamicAnimatorWillResume:(UIDynamicAnimator *)animator;
- (void)dynamicAnimatorDidPause:(UIDynamicAnimator *)animator;

@end

属性

// 行为执行时间
@property (nonatomic, readonly) NSTimeInterval elapsedTime;
// 判断是否正在执行
@property (nonatomic, readonly, getter = isRunning) BOOL running;

设置动画组件Item的动力属性

UIDynamicItemBehavior

UIDynamicItemBehavior *dynamic = [[UIDynamicItemBehavior alloc] init];
[animator addBehavior:dynamic];
[dynamic addItem:view];

// 相关属性
@property (readwrite, nonatomic) CGFloat elasticity; // Usually between 0 (inelastic) and 1 (collide elastically)
@property (readwrite, nonatomic) CGFloat friction; // 0 being no friction between objects slide along each other
@property (readwrite, nonatomic) CGFloat density; // 1 by default
@property (readwrite, nonatomic) CGFloat resistance; // 0: no velocity damping
@property (readwrite, nonatomic) CGFloat angularResistance; // 0: no angular velocity damping

为动画组件添加具体行为

吸引行为 UISnapBehavior

UISnapBehavior *snap = [[UISnapBehavior alloc]
                        initWithItem:view
                        snapToPoint:CGPointMake(, )];
snap.damping = 0.9;//阻尼系数
[animator addBehavior:snap];

重力行为 UIGravityBehavior

UIGravityBehavior *gravity = [[UIGravityBehavior alloc] init];
// 重力矢量方向 默认为 (0,1)
gravity.gravityDirection = CGVectorMake(, );
// 重力大小
gravity.magnitude = ;
[animator addBehavior:gravity];
[gravity addItem:view];

碰撞行为 UICollisionBehavior

UICollisionBehavior *collision = [[UICollisionBehavior alloc] init];
// 边界刚体碰撞
collision.translatesReferenceBoundsIntoBoundary = YES;
[animator addBehavior:collision];
[collision addItem:view];

作用力行为 UIPushBehavior

UIPushBehavior *push = [[UIPushBehavior alloc] initWithItems:@[view]
                                                        mode:UIPushBehaviorModeInstantaneous];
//    UIPushBehaviorModeContinuous 持续作用力
//    UIPushBehaviorModeInstantaneous 瞬间作用力
push.active = YES;
push.pushDirection = CGVectorMake(, );
[animator addBehavior:push];

效果演示

UIDynamicItemBehavior+UIGravityBehavior+UICollisionBehavior

- (void)viewDidLoad
{
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.

  animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

  dynamic = [[UIDynamicItemBehavior alloc]init];
  dynamic.elasticity = 0.7;// 弹力系数
  [animator addBehavior:dynamic];

  gravity = [[UIGravityBehavior alloc]init];
  gravity.gravityDirection = CGVectorMake(, );// 重力矢量方向
  [animator addBehavior:gravity];

  collision = [[UICollisionBehavior alloc]init];
  collision.translatesReferenceBoundsIntoBoundary = YES;// 边界刚体碰撞
  [animator addBehavior:collision];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  CGFloat width = self.view.frame.size.width;

  int x = arc4random()%(int)width;
  int z = arc4random()%;

  UIView *view = [[UIView alloc]initWithFrame:CGRectMake(x, , +z, +z)];
  view.backgroundColor = [UIColor greenColor];
  view.layer.borderColor = [UIColor blueColor].CGColor;
  view.layer.borderWidth = 1.0;
  view.layer.masksToBounds = YES;
  [self.view addSubview:view];

  [dynamic addItem:view];
  [gravity addItem:view];
  [collision addItem:view];
}

UIPushBehavior+UIGravityBehavior

- (void)viewDidLoad
{
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.

  animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

  UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];
  [self.view addGestureRecognizer:tap];

  gravity = [[UIGravityBehavior alloc] init];
  gravity.gravityDirection = CGVectorMake(, );
  gravity.magnitude = 10.0;
  [animator addBehavior:gravity];
}

- (void)tap:(UITapGestureRecognizer *)tap
{
  CGPoint point = [tap locationInView:self.view];

  for (CGFloat i =  ; i < M_PI*; i = i + 0.2)
  {
    UIView *view = [[UIView alloc]initWithFrame:CGRectMake(, , , )];
    view.center = point;
    view.backgroundColor = [UIColor blueColor];
    view.layer.cornerRadius = ;
    view.layer.masksToBounds = YES;
    [self.view addSubview:view];

    UIPushBehavior *push = [[UIPushBehavior alloc] initWithItems:@[view]
                                                            mode:UIPushBehaviorModeInstantaneous];
    push.active = YES;
    push.angle = i;
    push.magnitude = 0.05;
    [animator addBehavior:push];

    [gravity addItem:view];
  }
}

UIDynamicItemBehavior+UICollisionBehavior+UISnapBehavior

- (void)viewDidLoad
{
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.

  animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

  dynamic = [[UIDynamicItemBehavior alloc]init];
  dynamic.elasticity = 0.7;// 弹力系数
  [animator addBehavior:dynamic];

  collision = [[UICollisionBehavior alloc]init];
  collision.translatesReferenceBoundsIntoBoundary = YES;// 边界刚体碰撞
  [animator addBehavior:collision];

  CGFloat width = self.view.frame.size.width;
  CGFloat height = self.view.frame.size.height;

  red = [[UIView alloc] initWithFrame:CGRectMake(, , , )];
  red.center = CGPointMake(width/, height/+);
  red.backgroundColor = [UIColor redColor];
  red.layer.cornerRadius = 15.0;
  red.layer.masksToBounds = YES;
  [self.view addSubview:red];

  [collision addItem:red];

  UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];
  [self.view addGestureRecognizer:tap];
}

- (void)tap:(UITapGestureRecognizer *)tap
{
  CGPoint point = [tap locationInView:self.view];

  UIView *view = [[UIView alloc] initWithFrame:CGRectMake(, , , )];
  view.center = point;
  view.backgroundColor = [UIColor blueColor];
  view.layer.cornerRadius = 10.0;
  view.layer.masksToBounds = YES;
  [self.view addSubview:view];

  [collision addItem:view];

  UISnapBehavior *snap = [[UISnapBehavior alloc]
                          initWithItem:view
                          snapToPoint:red.center];
  snap.damping = 0.1;
  [animator addBehavior:snap];

  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
    [animator removeBehavior:snap];
  });
}