UIPushBehavior的简单使用

#import "PushView.h"

@interface PushView ()

@property (weak, nonatomic) UIImageView * imageView1;

@property (strong,nonatomic)UIDynamicAnimator * animator;

@property (strong,nonatomic)UIPushBehavior * push;

@property (assign,nonatomic)CGPoint beganPoint;

@property (assign,nonatomic)CGPoint endPoint;

@property (assign,nonatomic)CGPoint movePoint;

@end

@implementation PushView

- (instancetype)initWithFrame:(CGRect)frame{

  

  if (self = [superinitWithFrame:frame]) {

    

    self.backgroundColor = [UIColorwhiteColor];

    [selfsetupViews];

  }

  return self;

  

}

- (void)setupViews{

  

  UIImageView * imageView1 = [[UIImageViewalloc]init];

  imageView1.backgroundColor = [UIColorredColor];

  imageView1.frame = CGRectMake(50, 100, 100, 100);

  imageView1.layer.masksToBounds =YES;

  imageView1.layer.cornerRadius = imageView1.frame.size.width/2;

  imageView1.userInteractionEnabled =YES;

  _imageView1 = imageView1;

  [self addSubview:imageView1];

  

  

  

  UIPanGestureRecognizer * pan = [[UIPanGestureRecognizeralloc]initWithTarget:selfaction:@selector(pan:)];

  [selfaddGestureRecognizer:pan];

  

  /**

   UIPushBehavior是继承自UIDynamicBehavior，UIDynamicBehavior是继承自NSObject

   这个行为若有UICollisionBehavior如下，则这个行为最终停留在屏幕边缘，也就是他的父视图的边缘

   如果没有UICollisionBehavior这个行为的载体最终会消失滑出父视图的边缘

   */

  

  //UIPushBehaviorModeInstantaneous  力是瞬时的

  _push = [[UIPushBehavioralloc]initWithItems:@[self.imageView1]mode:UIPushBehaviorModeInstantaneous];

  

  //UIPushBehaviorModeContinuous  力是连续的

   _push = [[UIPushBehavioralloc]initWithItems:@[self.imageView1]mode:UIPushBehaviorModeContinuous];

  

  [self.animatoraddBehavior:_push];

  

  //创建了之后默认是YES用这个属性来决定这个行为是否执行

  NSLog(@"active %d ",_push.active);

  

  //加一个UICollisionBehavior就不会出现在屏幕外面

  UICollisionBehavior * collision = [[UICollisionBehavioralloc]initWithItems:@[self.imageView1]];

  collision.translatesReferenceBoundsIntoBoundary =YES;

  [self.animatoraddBehavior:collision];

  

  

}

- (void)pan:(UIPanGestureRecognizer *)pan{

  

  CGPoint location = [pan locationInView:self];

  

  if (UIGestureRecognizerStateBegan == pan.state) {

    

    _beganPoint = location;

    

  } elseif (UIGestureRecognizerStateChanged == pan.state){

    

    _movePoint = location;

    [selfsetNeedsDisplay];

    

  } elseif (UIGestureRecognizerStateEnded == pan.state){

    

    _endPoint = location;

    

    _push.active =YES;

    

    CGPoint offset =CGPointMake(_beganPoint.x -_endPoint.x,self.beganPoint.y -_endPoint.y);

    

    _push.active =YES;

    

    // 角度 默认的是0如果要配置力矢量UIPushBehavior，必须要设置magnitude和angle两个属性

    _push.angle = -atan2f(offset.y, -offset.x);

    

    // 推动行为的力矢量的大小默认是nil若为负则是力的反方向

    _push.magnitude =sqrtf(offset.x * offset.x + offset.y * offset.y) /50;

    

    //这个方法相当于设定angle和 magnitude

    [_push setAngle:-atan2f(offset.y, -offset.x)magnitude:sqrtf(offset.x * offset.x + offset.y * offset.y) /50];

    

    [selfclearLine];

    

  }

  

  

}

- (void)drawRect:(CGRect)rect{

  //绘制拉伸线路

  CGContextRef context =UIGraphicsGetCurrentContext();

  

  CGContextMoveToPoint(context, self.beganPoint.x,self.beganPoint.y);

  CGContextAddLineToPoint(context,_movePoint.x,_movePoint.y);

  

  CGContextSetLineWidth(context,5.0f);

  CGFloat length[] = {15.0,5.0};

  CGContextSetLineDash(context, 0.0, length, 2);

  [[UIColorblueColor]setStroke];

  

  CGContextDrawPath(context,kCGPathFillStroke);

}

- (void)clearLine{

  

  _beganPoint = CGPointZero;

  _movePoint =CGPointZero;

  _endPoint =CGPointZero;

  [selfsetNeedsDisplay];

  

}

- (UIDynamicAnimator *)animator{

  

  if (_animator ==nil) {

    _animator = [[UIDynamicAnimatoralloc]initWithReferenceView:self];

  }

  return_animator;

  

}

@end