####iOS7 Programming Cookbook 第二章学习笔记 UIPushBehavior
#####Animating Your UI Components With a Push
#####ViewController.m1
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98@interface ViewController ()
//方块view
@property (nonatomic, strong) UIView *squareView;
//UIDynamicAnimator，它通过底层的iOS物理引擎和动态项目之间的媒介,通过行为对象添加到动画师。
@property (nonatomic, strong) UIDynamicAnimator *animator;
//父类 UIDynamicBehavior，UIPushBehavior：推动行为持续或瞬时力量适用于一个或多个动态项目,使得这些项目改变相应位置。
@property (nonatomic, strong) UIPushBehavior *pushBehavior;
@end
@implementation ViewController
- (void) createSmallSquareView{
//创建方块 长宽
self.squareView = [[UIView alloc] initWithFrame:
CGRectMake(0.0f, 0.0f, 80.0f, 80.0f)];
//背景颜色
self.squareView.backgroundColor = [UIColor greenColor];
//初始化center
self.squareView.center = self.view.center;
//添加到view
[self.view addSubview:self.squareView];
}
- (void) createGestureRecognizer{
//创建并添加点击事件
UITapGestureRecognizer *tapGestureRecognizer =
[[UITapGestureRecognizer alloc] initWithTarget:self
action:@selector(handleTap:)];
//点击事件添加到view
[self.view addGestureRecognizer:tapGestureRecognizer];
}
- (void) createAnimatorAndBehaviors{
self.animator = [[UIDynamicAnimator alloc]
initWithReferenceView:self.view];//指定视图为self.view
//创建碰撞检测
UICollisionBehavior *collision = [[UICollisionBehavior alloc]
initWithItems:@[self.squareView]];
//基于系统，指定一个碰撞边界
collision.translatesReferenceBoundsIntoBoundary = YES;
//创建push行为self.squareView， UIPushBehaviorModeContinuous：选择连续力量
self.pushBehavior = [[UIPushBehavior alloc]
initWithItems:@[self.squareView]
mode:UIPushBehaviorModeContinuous];
//动画师添加碰撞检测，添加push行为
[self.animator addBehavior:collision];
[self.animator addBehavior:self.pushBehavior];
}
- (void) handleTap:(UITapGestureRecognizer *)paramTap{
//从方块中心和点击点得到角度
//(CGPoint) tapPoint = (x=221, y=133.5)
CGPoint tapPoint = [paramTap locationInView:self.view];
//绿色方块当前所在位置的 方块中心坐标 (CGPoint) $1 = (x=40, y=528)
CGPoint squareViewCenterPoint = self.squareView.center;
//x ,181 = 221 - 40
CGFloat deltaX = tapPoint.x - squareViewCenterPoint.x;
//y, - 394.5 = 133.5 - 528
CGFloat deltaY = tapPoint.y - squareViewCenterPoint.y;
//atan 返回给定的 X 及 Y 坐标值的反正切值。
//反正切的角度值等于x轴正方向与通过原点和给定坐标点 (Y坐标， X坐标) 的射线之间的夹角。
//结果以弧度表示并介于 -pi 到 pi 之间（不包括 -pi）。
//-1.1406413
//检测2点之间的角度arc tangent 2((p1.x - p2.x), (p1.y - p2.y))
CGFloat angle = atan2(deltaY, deltaX);
//设置pushBehavior角的弧度
[self.pushBehavior setAngle:angle];
//从点击点和矩形
/*
距离公式: ((p1.x - p2.x)^2 + (p1.y - p2.y)^2)
*/
//pow 计算x的y次幂
//distanceBetweenPoints （434.04062）＝ sqrt ((181)^2+(133.5-528)^2);
CGFloat distanceBetweenPoints =
sqrt(pow(tapPoint.x - squareViewCenterPoint.x, 2.0) +
pow(tapPoint.y - squareViewCenterPoint.y, 2.0));
//设置力矢量的大小434/200
[self.pushBehavior setMagnitude:distanceBetweenPoints / 200.0f];
}
- (void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
[self createGestureRecognizer];
[self createSmallSquareView];
[self createAnimatorAndBehaviors];
}
@end
