Swift中创建有动态交互性的用户界面UIDynamics之UIAttachmentBehavior,UIDynamicItemBehavior的使用（二）

前言:动力项目关联UIAttachmentBehavior的使用

• 吸附主要发生在：元素与锚点、元素与元素之间。
• 当元素与锚点连接，元素的运动依赖于锚点。
• 当元素与元素连接，两个元素的运动彼此影响。
• 有的吸附行为支持两个元素和一个锚点。

如果喜欢UIkit的动力行为所内置的默认物理特性，但是想使用动力行为为控制的动力项目设置不同的特征，比如质量和弹性，如何实现呢，这里就需要用到这个类UIDynamicItemBehavior

元素和锚点之前的吸附

class ViewController: UIViewController{
    var anchorView :UIView!
    
    var dynamicItem1View :UIView!
    var animator:UIDynamicAnimator?
    var attachmentBehavior :UIAttachmentBehavior?
    override func viewDidLoad() {
        super.viewDidLoad()
        
        anchorView = UIView.init(frame: CGRect.init(x: 0, y: 0,  10, height: 10))
        anchorView.center = CGPoint.init(x: 175, y: 250)
        anchorView.backgroundColor  = UIColor.red
        view.addSubview(anchorView)
        
        dynamicItem1View = UIView.init(frame: CGRect.init(x: 0, y: 0,  50, height: 50))
        dynamicItem1View.center = CGPoint.init(x: 125, y: 125)
        dynamicItem1View.backgroundColor = UIColor.blue
        view.addSubview(dynamicItem1View)
    }
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        animator = UIDynamicAnimator.init(referenceView: view)
        let gravity = UIGravityBehavior.init(items: [dynamicItem1View])
        animator?.addBehavior(gravity)
        
        
        let collision = UICollisionBehavior.init(items: [dynamicItem1View] as! [UIDynamicItem])
        collision.translatesReferenceBoundsIntoBoundary = true//确保动画对象使用父视图作为参考视图进行初始化
        animator!.addBehavior(collision)
        
        
        attachmentBehavior = UIAttachmentBehavior.init(item: dynamicItem1View, attachedToAnchor: anchorView.center)
        attachmentBehavior!.length = 50
        animator!.addBehavior(attachmentBehavior!)
    }
    
}

元素和锚点之间的吸附，offset参数设置元素吸附力作用点的偏移量

 attachmentBehavior = UIAttachmentBehavior.init(item: dynamicItem1View, offsetFromCenter: UIOffset.init(horizontal: 25, vertical: 0), attachedToAnchor: anchorView.center)

元素和元素之间的吸附

import UIKit
class ViewController: UIViewController{
   
    var dynamicItem1View :UIView!
    var dynamicItem2View :UIView!
    var animator:UIDynamicAnimator?
    var attachmentBehavior :UIAttachmentBehavior?
    override func viewDidLoad() {
        super.viewDidLoad()
        
        dynamicItem1View = UIView.init(frame: CGRect.init(x: 0, y: 0,  50, height: 50))
        dynamicItem1View.center = CGPoint.init(x: 125, y: 125)
        dynamicItem1View.backgroundColor = UIColor.black
        view.addSubview(dynamicItem1View)
        
        let redView1 = UIView.init(frame: CGRect.init(x: 0, y: 0,  10, height: 10))
        redView1.backgroundColor = UIColor.red
        dynamicItem1View.addSubview(redView1)
        redView1.center = CGPoint.init(x: 25, y: 25)
        
        
        dynamicItem2View = UIView.init(frame: CGRect.init(x: 0, y: 0,  50, height: 50))
        dynamicItem2View.center = CGPoint.init(x: 175, y: 250)
        dynamicItem2View.backgroundColor = UIColor.blue
        view.addSubview(dynamicItem2View)
        let redView0 = UIView.init(frame: CGRect.init(x: 0, y: 0,  10, height: 10))
        redView0.backgroundColor = UIColor.red
        dynamicItem2View.addSubview(redView0)
        redView0.center = CGPoint.init(x: 25, y: 25)
        
    }
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        animator = UIDynamicAnimator.init(referenceView: view)
        let gravity = UIGravityBehavior.init(items: [dynamicItem1View])
        animator?.addBehavior(gravity)
        
        
        let collision = UICollisionBehavior.init(items: [dynamicItem1View,dynamicItem2View] as! [UIDynamicItem])
        collision.translatesReferenceBoundsIntoBoundary = true//确保动画对象使用父视图作为参考视图进行初始化
        animator!.addBehavior(collision)
        
        
        attachmentBehavior = UIAttachmentBehavior.init(item: dynamicItem1View, attachedTo: dynamicItem2View)
        attachmentBehavior!.length = 100
        animator!.addBehavior(attachmentBehavior!)
    }
    
}

元素和元素之间的吸附设置偏移量

 

 attachmentBehavior = UIAttachmentBehavior.init(item: dynamicItem1View, offsetFromCenter: UIOffset.init(horizontal: 0, vertical: -25), attachedTo: dynamicItem2View, offsetFromCenter: UIOffset.init(horizontal: 0, vertical: 25))

        //我们可以通过anchorPoint属性获得锚点位置，附发生在元素和元素之间的时候，该属性的值为(0, 0)
        @property (readwrite, nonatomic) CGPoint anchorPoint;
        //作用点的距离
        @property (readwrite, nonatomic) CGFloat length;
        //振动频率，值越大，弹性运动的频率越快
        @property (readwrite, nonatomic) CGFloat frequency;
        //弹性阻力 值越大，阻力越大，弹性运动震动的幅度越小。
        @property (readwrite, nonatomic) CGFloat damping; // 1: critical damping
        //旋转阻力，指围绕一点旋转所受的阻力，默认值0.0，值越大，阻力越大。
        @property (readwrite, nonatomic) CGFloat frictionTorque
        //运动范围
        @property (readwrite, nonatomic) UIFloatRange attachmentRange

UIDynamicItemBehavior的使用

•      allowsRotation ：允许动力项目在动画过程中发生旋转
•      resistance：动力项目移动时的阻力，可以从0到CGFLOAT_MAX
•      friction：在其他动力项目碰撞或者发生摩擦是，应该有多大的摩擦力，值越高，摩擦力越大
•      elasticity：0.0到1.0的浮点数，值定理了动力项目可以有多大的弹性
•      density：一个浮点数，0到1，默认1，对象的质量，就是密度，同样狂傲越低重量越轻

 

class ViewController: UIViewController{
    var topView:UIView!
    var bottomView:UIView!
    var animator:UIDynamicAnimator?
   
    func newViewWithCenter(center:CGPoint,backgroundColor:UIColor) ->UIView{
       let newView = UIView.init(frame: CGRect.init(x: 0, y: 0,  50, height: 50))
        newView.center = center
        newView.backgroundColor  = backgroundColor
        return newView
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        topView = newViewWithCenter(center: CGPoint.init(x: 100, y: 0), backgroundColor: UIColor.green)
        bottomView = newViewWithCenter(center: CGPoint.init(x: 200, y: 0), backgroundColor: UIColor.red)
        view.addSubview(topView)
        view.addSubview(bottomView)
        
       
        
    }
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        animator = UIDynamicAnimator.init(referenceView: view)
        let gravity = UIGravityBehavior.init(items: [topView,bottomView])
        animator?.addBehavior(gravity)
        
        let collision = UICollisionBehavior.init(items: [topView,bottomView])
        collision.translatesReferenceBoundsIntoBoundary = true
        animator!.addBehavior(collision)
        
        let moreElastiItem = UIDynamicItemBehavior.init(items: [bottomView])
        moreElastiItem.elasticity = 1
        
        let lessElastiItem = UIDynamicItemBehavior.init(items: [topView])
        moreElastiItem.elasticity = 0.5
        animator?.addBehavior(moreElastiItem)
        animator?.addBehavior(lessElastiItem)
    }
    
}