什么是UIDynamic?
UIDynamic是从iOS 7开始引入的一种新技术，隶属于UIKit框架
可以认为是一种物理引擎，能模拟和仿真现实生活中的物理现象
重力、弹性碰撞等现象
UIDynamic使用步骤
- 创建一个物理仿真器（顺便设置仿真范围）
- 创建相应的物理仿真行为（顺便添加物理仿真元素）
- 将物理仿真行为添加到物理仿真器中，开始仿真
物理仿真元素
不是任何对象都能做物理仿真元素，不是任何对象都能进行物理仿真
哪些对象才能做物理仿真元素？
任何遵守了UIDynamicItem协议的对象
UIView默认已经遵守了UIDynamicItem协议，因此任何UI控件都能做物理仿真
UICollectionViewLayoutAttributes类默认也遵守UIDynamicItem协议
物理仿真行为
- UIDynamic提供了以下几种物理仿真行为
- UIGravityBehavior：重力行为
- UICollisionBehavior：碰撞行为
- UISnapBehavior：捕捉行为
- UIPushBehavior：推动行为
- UIAttachmentBehavior：附着行为
- UIDynamicItemBehavior：动力元素行为
物理仿真器
它可以让物理仿真元素执行物理仿真行为，它是UIDynamicAnimator类型的对象
UIDynamicAnimator的初始化
- (instancetype)initWithReferenceView:(UIView *)view;
view参数：是一个参照视图，表示物理仿真的范围
UIDynamicAnimator的常见方法
//添加1个物理仿真行为
- (void)addBehavior:(UIDynamicBehavior *)behavior;
//移除1个物理仿真行为
- (void)removeBehavior:(UIDynamicBehavior *)behavior;
//移除之前添加过的所有物理仿真行为
- (void)removeAllBehaviors;
UIDynamicAnimator的常见属性
//参照视图
@property (nonatomic, readonly) UIView* referenceView;
//添加到物理仿真器中的所有物理仿真行为
@property (nonatomic, readonly, copy) NSArray* behaviors;
//是否正在进行物理仿真
@property (nonatomic, readonly, getter = isRunning) BOOL running;
//代理对象（能监听物理仿真器的仿真过程，比如开始和结束）
@property (nonatomic, assign) id <UIDynamicAnimatorDelegate> delegate;
直接上代码
#import "ViewController.h"
@interface ViewController ()
@property (nonatomic,strong) UIDynamicAnimator *animator;
@property (weak, nonatomic) IBOutlet UISegmentedControl *segmented;
@property (weak, nonatomic) IBOutlet UIView *blueView;
@property (weak, nonatomic) IBOutlet UIView *redView;
@property (weak, nonatomic) IBOutlet UIView *orangeView;
@end
@implementation ViewController
-(void)viewDidLoad {
[super viewDidLoad];
self.blueView.transform = CGAffineTransformMakeRotation(M_PI_4);
self.segmented.transform = CGAffineTransformMakeRotation(-M_PI / 8);
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent: (UIEvent *)event {
//创建重力行为
UIGravityBehavior *gravityBehavior = [[UIGravityBehavior alloc]init];
[gravityBehavior addItem:self.blueView];
[gravityBehavior addItem:self.orangeView];
//加速度
gravityBehavior.magnitude = 3;
//创建碰撞行为
UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc]init];
//碰撞类型为元素和边界
collisionBehavior.collisionMode = UICollisionBehaviorModeEverything;
CGFloat Y = self.view.frame.size.height - CGRectGetHeight(self.redView.frame);
CGFloat X = self.view.frame.size.width;
CGFloat height = self.view.frame.size.height;
//设置红色的View为底边界,左边框跟右边框作为边界
[collisionBehavior addBoundaryWithIdentifier:@"collision1" fromPoint:CGPointMake(0,Y) toPoint:CGPointMake(X, Y)];
[collisionBehavior addBoundaryWithIdentifier:@"collision2" fromPoint:CGPointMake(0, 0) toPoint:CGPointMake(0, height)];
[collisionBehavior addBoundaryWithIdentifier:@"collision3" fromPoint:CGPointMake(X,0) toPoint:CGPointMake(X, height)];
[collisionBehavior addItem:self.blueView];
[collisionBehavior addItem:self.segmented];
[collisionBehavior addItem:self.orangeView];
[self.animator addBehavior:collisionBehavior];
[self.animator addBehavior:gravityBehavior];
}
- (UIDynamicAnimator *)animator{
if (_animator == nil) {
_animator = [[UIDynamicAnimator alloc]init];
}
return _animator;
}
@end
效果
