[摘要]本文是對UIDynamic - 推動行為: UIPushBehavior的講解，對學習IOS蘋果軟件開發有所幫助,與大家分享。

用途:

從一個點移動到另外一個點;

相關屬性:

mode : UIPushBehaviorModeContinuous //推移模式

angle : setAngle //推移角度

magnitude : setMagnitude //速度 每1個magnigude將會引起100/平方秒的加速度

圖片說明:

p1 : squareView的中心點 p2 : 單擊的點

促使squareView朝著p2移動，因為加了UICollisionBehavior，所以移動時又不會超過邊界

代碼:

 //
 //  YFPushBehaviorViewController.m
 //  BigShow1949
 //
 //  Created by apple on 16/8/25.
 //  Copyright © 2016年 BigShowCompany. All rights reserved.
 //
 
 #import "YFPushBehaviorViewController.h"
 
 @interface YFPushBehaviorViewController ()
 @property(nonatomic,strong)UIDynamicAnimator *animator;
 @property (nonatomic, strong) UIView *squareView;
 @property (nonatomic, strong) UIPushBehavior *pushBehavior;
 
 @end
 
 @implementation YFPushBehaviorViewController
 - (void)viewDidLoad {
 
     [super viewDidLoad];
     self.view.backgroundColor = [UIColor whiteColor];
 
 }
 
 - (void)viewDidAppear:(BOOL)animated{
     [super viewDidAppear:animated];
     
     // 創建一個正方形
     self.squareView =[[UIView alloc] initWithFrame: CGRectMake(0.0f, 0.0f, 80.0f, 80.0f)];
     self.squareView.backgroundColor = [UIColor greenColor];
     self.squareView.center = self.view.center;
     [self.view addSubview:self.squareView];
     
     // 視圖單機手勢
     [self createGestureRecognizer];
     
     [self createAnimatorAndBehaviors];
 }
 
 - (void) createGestureRecognizer{
     UITapGestureRecognizer *tapGestureRecognizer =
     [[UITapGestureRecognizer alloc] initWithTarget:self  action:@selector(handleTap:)];
     [self.view addGestureRecognizer:tapGestureRecognizer];
 }
 
 - (void) handleTap:(UITapGestureRecognizer *)paramTap{
     
     CGPoint tapPoint = [paramTap locationInView:self.view];  //p2
     CGPoint squareViewCenterPoint = self.squareView.center;  //p1
     
     CGFloat deltaX = tapPoint.x - squareViewCenterPoint.x;
     CGFloat deltaY = tapPoint.y - squareViewCenterPoint.y;
     CGFloat angle = atan2(deltaY, deltaX);
     [self.pushBehavior setAngle:angle];  //推移的角度
     
     //勾股
     CGFloat distanceBetweenPoints =
     sqrt(pow(tapPoint.x - squareViewCenterPoint.x, 2.0) +
          pow(tapPoint.y - squareViewCenterPoint.y, 2.0));
     //double pow(double x, double y）;計算以x為底數的y次冪
     //double sqrt (double);開平方
     
     //推力的大小（移動速度）
     [self.pushBehavior setMagnitude:distanceBetweenPoints / 50.0f];
     //每1個magnigude將會引起100/平方秒的加速度，這裡分母越大，速度越小
     
 }
 - (void) createSmallSquareView{
     self.squareView =[[UIView alloc] initWithFrame: CGRectMake(0.0f, 0.0f, 80.0f, 80.0f)];
     
     self.squareView.backgroundColor = [UIColor greenColor];
     self.squareView.center = self.view.center;
     
     [self.view addSubview:self.squareView];
 }
 - (void) createAnimatorAndBehaviors{
     self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
     
     /* Create collision detection */
     UICollisionBehavior *collision = [[UICollisionBehavior alloc]
                                       initWithItems:@[self.squareView]];
     collision.translatesReferenceBoundsIntoBoundary = YES;
     
     self.pushBehavior = [[UIPushBehavior alloc]
                          initWithItems:@[self.squareView]
                          mode:UIPushBehaviorModeContinuous];
     
     [self.animator addBehavior:collision];
     [self.animator addBehavior:self.pushBehavior];
 }
 
 @end