【ios】UIDynamic物理模拟实现物理碰撞

一、需求：请实现下图所示的动画(物理碰撞)

 

 

二、上面引入过uidynamic 可以实现碰撞的物理效果动画，how to start ?

在工程中导入uikit，从headers 找一些uidynamic，发现了uidynamicanimator.h,uidynamicbehavior,uidynamicitembehavior

既然是要动画效果 那就应该是uidynamicanimator.h

到uidynamicanimator.h 头文件去查看注释

// when you initialize a dynamic animator with this method, you should only associates views with your behaviors.

// the behaviors (and their dynamic items) that you add to the animator employ the reference view’s coordinate system.

- (instancetype)initwithreferenceview:(uiview *)view ns_designated_initializer;

大概意思是使用这个初始化方法的时候，需要为你的试图关联behaviors

what’s the behaviors ? jump into defination 然而还不是很懂，uidynamicbehavior,那就查看api (注意文档中的如下描述)。

this parent class, uidynamicbehavior, is inherited by the primitive dynamic behavior classes uiattachmentbehavior, uicollisionbehavior, uigravitybehavior, uidynamicitembehavior, uipushbehavior, and uisnapbehavior.

文档中提到uidynamicbehavior的父类，那么uidynamicbehavior父类(dynamic 行为相关类)描述什么行为呢?

uiattachmentbehavior：附着行为

uicollisionbehavior：碰撞行为

uigravitybehavior：重力行为

uidynamicitembehavior：动态元素行为

uipushbehavior：推行为

uisnapbehavior：吸附行为

上述的各种行为可单独使用，也可以组合使用更复杂的动画效果。

解决方案的思路就引导到这边，也就可以实现上述需求。dynamic 行为相关类的属性可自行研究。

三、解决方案。

上述需求的解决方案(我这边用的是6sp的模拟器奥，因为在设置floor的y坐标是600)

既然是球落地效果，必然有两个模拟对象：floor，basketball

1.创建uidynamicanimator 对象

self.animator = [[uidynamicanimator alloc] initwithreferenceview:self.view];

2.刚刚在api 看到了初始化uidynamicanimator需要关联一个或者多个行为

nsarray *animatorobjects = @[self.imagev1];

// 刚刚在api 看到了初始化uidynamicanimator需要关联一个或者多个行为

self.gravitybehav = [[uigravitybehavior alloc] initwithitems:animatorobjects];

self.colision = [[uicollisionbehavior alloc] initwithitems:animatorobjects];

3.如果你想监听碰撞的状态，可以设置一下代理

self.colision.collisiondelegate = self;

4.设置碰撞边界

[self.colision addboundarywithidentifier:@"boundaryline" frompoint:cgpointmake(0, 600) topoint:cgpointmake(screenwith, 600)];

5.设置动态行为参数

// 设置动态行为参数

uidynamicitembehavior *itembehavior = [[uidynamicitembehavior alloc] initwithitems:animatorobjects];

// 设置弹性

[itembehavior setelasticity:0.5];

6.行为创建了，别忘了给animator添加上

[self.animator addbehavior:self.gravitybehav];

[self.animator addbehavior:self.colision];

[self.animator addbehavior:itembehavior];

三、下面代码只能说功能实现

ps：以下代码不符合代码书写规范

//

// viewcontroller.m

// dynamicanimation

//

// created by jeversonjee on 16/5/27.

// copyright © 2016年 jeversonjee. all rights reserved.

//

#import "viewcontroller.h"

#define screenwith [uiscreen mainscreen].bounds.size.width

#define screenheight [uiscreen mainscreen].bounds.size.height

@interface viewcontroller ()

@property (nonatomic, strong) uidynamicanimator *animator;

@property (nonatomic, strong) uigravitybehavior *gravitybehav;

@property (nonatomic, strong) uicollisionbehavior *colision;

@property (nonatomic, strong) uiimageview *imagev1;

@property (nonatomic, strong) uiimageview *imagev2;

@end

@implementation viewcontroller

- (void)viewdidload {

[super viewdidload];

// do any additional setup after loading the view, typically from a nib.

[self jjcollisionbehav];

}

- (void)jjcollisionbehav {

// 创建碰撞需要的对象

[self jjcreateball];

[self jjcreatefloor];

// 创建uidynamicanimator 对象

self.animator = [[uidynamicanimator alloc] initwithreferenceview:self.view];

nsarray *animatorobjects = @[self.imagev1];

// 刚刚在api 看到了初始化uidynamicanimator需要关联一个或者多个行为

self.gravitybehav = [[uigravitybehavior alloc] initwithitems:animatorobjects];

self.colision = [[uicollisionbehavior alloc] initwithitems:animatorobjects];

// 这里设置代理是为了监听碰撞状态的，可以去了解一下代理方法

self.colision.collisiondelegate = self;

// 设置碰撞边界

[self.colision addboundarywithidentifier:@"boundaryline" frompoint:cgpointmake(0, 600) topoint:cgpointmake(screenwith, 600)];

// 设置动态行为参数

uidynamicitembehavior *itembehavior = [[uidynamicitembehavior alloc] initwithitems:animatorobjects];

// 设置弹性

[itembehavior setelasticity:0.5];

// 创建了行为需要animator添加

[self.animator addbehavior:self.gravitybehav];

[self.animator addbehavior:self.colision];

[self.animator addbehavior:itembehavior];

}

-(void)collisionbehavior:(uicollisionbehavior *)behavior endedcontactforitem:(id)item withboundaryidentifier:(id)identifier {

nslog(@"collisionbehavior=%@", item);

nsstring *identifierstr = [nsstring stringwithformat:@"%@", identifier];

nslog(@"s=%@", identifier);

if ( [identifierstr isequaltostring:@"boundaryline"] ) {

[self.imagev2 setbackgroundcolor:[uicolor graycolor]];

[uiview animatewithduration:2 animations:^(void){

[self.imagev2 setbackgroundcolor:[uicolor graycolor]];

}];

}

}

-(void)jjcreateball {

_imagev1 = [[uiimageview alloc] initwithimage:[uiimage imagenamed:@"basketball"]];

_imagev1.frame = cgrectmake(100, 100, 60, 60);

[self.view addsubview:_imagev1];

}

- (void)jjcreatefloor {

_imagev2 = [[uiimageview alloc] init];

[_imagev2 setbackgroundcolor:[uicolor graycolor]];

_imagev2.frame = cgrectmake(0, 600, screenwith, screenheight - 400);

[self.view addsubview:_imagev2];

}

-(void)didreceivememorywarning {

[super didreceivememorywarning];

// dispose of any resources that can be recreated.

}

@end