来自IOS7 by tutorials 下面是个人的一点翻译总结
1,首先在初始化方法李画一个方块
UIView* square = [[UIView alloc] initWithFrame:
CGRectMake(100, 100, 100, 100)];
square.backgroundColor = [UIColor grayColor]; [self.view addSubview:square];
2,声明两个变量。
UIDynamicAnimator* _animator;
UIGravityBehavior* _gravity;
3,初始化
_animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
_gravity = [[UIGravityBehavior alloc] initWithItems:@[square]]; [_animator addBehavior:_gravity];
4,闲着这个方块直接掉出屏幕了,我们需要加边框。
声明变量
UICollisionBehavior* _collision;
代码
_collision = [[UICollisionBehavior alloc] initWithItems:@[square]];
_collision.translatesReferenceBoundsIntoBoundary = YES; [_animator addBehavior:_collision];
5,多个 方块间的冲突
再声明一个长条。
UIView* barrier = [[UIView alloc]
initWithFrame:CGRectMake(0, 300, 130, 20)];
barrier.backgroundColor = [UIColor redColor]; [self.view addSubview:barrier];
我们看见方块穿过了长条。
修改代码
_collision = [[UICollisionBehavior alloc] initWithItems:@[square, barrier]];
这时长条被砸掉下去了。
6,我们把长条也弄成方框的边框。
_collision = [[UICollisionBehavior alloc] initWithItems:@[square]];
// add a boundary that coincides with the top edge
CGPoint rightEdge = CGPointMake(barrier.frame.origin.x + barrier.frame.size.width,
barrier.frame.origin.y); [_collision addBoundaryWithIdentifier:@"barrier"
fromPoint:barrier.frame.origin toPoint:rightEdge];
可以看见方框被长条弹开并落在了底部。
7,每个动画都由一个方法来执行,如碰撞,反弹等等...添加如下代码
_collision.action = ^{ NSLog(@"%@, %@",
NSStringFromCGAffineTransform(square.transform), NSStringFromCGPoint(square.center));
};
上面代码打印出方框下落时,中心和属性的变化。square.center是方框的中心,square.transform是方框的属性。
第一部分你会看到方框的中心square.center,的Y轴数据在变化,如
2014-07-24 11:41:42.133 DynamicsPlayground[766:60b] [1, 0, 0, 1, 0, 0], {150, 161}
2014-07-24 11:41:42.149 DynamicsPlayground[766:60b] [1, 0, 0, 1, 0, 0], {150, 164}
2014-07-24 11:41:42.167 DynamicsPlayground[766:60b] [1, 0, 0, 1, 0, 0], {150, 167}
当方块撞到长条时,方块开始转动,这时打印的结果是
2014-07-24 11:41:42.649 DynamicsPlayground[766:60b] [0.80305022, 0.59591132, -0.59591132, 0.80305022, 0, 0], {170, 266}
2014-07-24 11:41:42.666 DynamicsPlayground[766:60b] [0.7690773, 0.63915575, -0.63915575, 0.7690773, 0, 0], {172, 269}
2014-07-24 11:41:42.683 DynamicsPlayground[766:60b] [0.72068948, 0.69325799, -0.69325799, 0.72068948, 0, 0], {174, 272}
8,对象的动态行为是采用的 UIDynamicItem 协议 ,下面是协议的定义。
@protocol UIDynamicItem <NSObject>
@property (nonatomic, readwrite) CGPoint center;
@property (nonatomic, readonly) CGRect bounds;
@property (nonatomic, readwrite) CGAffineTransform transform;
@end
9,碰撞通知。添加代码在.m文件里。
@interface ViewController () <UICollisionBehaviorDelegate> @end
碰撞后
_collision.collisionDelegate = self;
碰撞后方法
- (void)collisionBehavior:(UICollisionBehavior *)behavior beganContactForItem:(id<UIDynamicItem>)item
withBoundaryIdentifier:(id<NSCopying>)identifier atPoint:(CGPoint)p {
NSLog(@"Boundary contact occurred - %@", identifier); }
可以看到碰撞后打印的信息,。
2014-07-24 12:15:45.124 DynamicsPlayground[820:60b] Boundary contact occurred - barrier
2014-07-24 12:15:45.692 DynamicsPlayground[820:60b] Boundary contact occurred - (null)
10,在打印后面添加代码
UIView* view = (UIView*)item; view.backgroundColor = [UIColor yellowColor];
[UIView animateWithDuration:0.3
animations:^{
view.backgroundColor = [UIColor grayColor];
}];
会看到方块在每次碰撞后发生的颜色变化。
11,配置属性。
下面代码追加在viewDidLoad方法的底部,
UIDynamicItemBehavior* itemBehaviour =
[[UIDynamicItemBehavior alloc] initWithItems:@[square]];
itemBehaviour.elasticity = 0.6;
[_animator addBehavior:itemBehaviour];
发现方块变得更有弹性了。除了弹性,itemBehaviour有更多其他属性可以更改。
12,添加动态行为
ViewController.m里添加一布尔型变量
BOOL _firstContact;
下面代码添加到协议方法里。
if (!_firstContact) {
_firstContact = YES;
UIView* square = [[UIView alloc] initWithFrame:CGRectMake(30, 0, 100, 100)];
square.backgroundColor = [UIColor grayColor];
[self.view addSubview:square];
[_collision addItem:square];
[_gravity addItem:square];
UIAttachmentBehavior* attach = [[UIAttachmentBehavior alloc]
initWithItem:view
attachedToItem:square];
[_animator addBehavior:attach];
}
两个方块被一根隐藏得线联系起来。
来自-IOS7 by tutorials,第二章第一节,目前网上有英文版下载,无中文版翻译。
--原创可转载 ,如有不恰当的地方可留言--guanliyang