//

//  RootViewController.m

//  DynamicView

//

//  Copyright (c) 2014年 Y.X. All rights reserved.

//

#import "RootViewController.h"

@interface RootViewController ()

@property (nonatomic, strong) UIView              *gravityView;

@property (nonatomic, strong) UIDynamicAnimator   *animator;     // 力学引擎

@end

@implementation RootViewController

- (void)viewDidLoad

{

    [super viewDidLoad];

    // 创建一个view

    _gravityView = [[UIView alloc] initWithFrame:CGRectMake(, , , )];

    _gravityView.backgroundColor = [UIColor redColor];

    [self.view addSubview:_gravityView];

    // 创建力学引擎并指定一个view来影响这个view的坐标系统

    _animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

    // 创建一个重力感应的行为,_gravityView将遵守这个行为,并提交给力学引擎

    UIGravityBehavior *gravity = \

        [[UIGravityBehavior alloc] initWithItems:@[_gravityView]];

    [_animator addBehavior:gravity];

    // 创建一个边界碰撞行为,_gravityView将遵守这个行为,并提交给力学引擎

    UICollisionBehavior *collision = \

        [[UICollisionBehavior alloc] initWithItems:@[_gravityView]];

    collision.translatesReferenceBoundsIntoBoundary = YES; // 开启边界范围限制

    [_animator addBehavior:collision];

}

@end