UICollisionBehavior.h

#if USE_UIKIT_PUBLIC_HEADERS || !__has_include(<UIKitCore/UICollisionBehavior.h>)
//
//  UICollisionBehavior.h
//  UIKit
//
//  Copyright (c) 2012-2018 Apple Inc. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <UIKit/UIView.h>
#import <UIKit/UIBezierPath.h>
#import <UIKit/UIDynamicBehavior.h>

NS_ASSUME_NONNULL_BEGIN

@class UICollisionBehavior;



/* 碰撞类型 <枚举> */
typedef NS_OPTIONS(NSUInteger, UICollisionBehaviorMode) {
    UICollisionBehaviorModeItems        = 1 << 0,       /// Item之间的碰撞
    UICollisionBehaviorModeBoundaries   = 1 << 1,       /// 边界碰撞
    UICollisionBehaviorModeEverything   = NSUIntegerMax /// 碰撞所有
} NS_ENUM_AVAILABLE_IOS(7_0);



///!!!: 碰撞行为代理 <协议>
@protocol UICollisionBehaviorDelegate <NSObject>

@optional
// 两个Item开始碰撞时的回调
- (void)collisionBehavior:(UICollisionBehavior *)behavior beganContactForItem:(id <UIDynamicItem>)item1 withItem:(id <UIDynamicItem>)item2 atPoint:(CGPoint)p;
// 两个Item结束碰撞时的回调
- (void)collisionBehavior:(UICollisionBehavior *)behavior endedContactForItem:(id <UIDynamicItem>)item1 withItem:(id <UIDynamicItem>)item2;

// Item和碰撞边界开始碰撞时的回调
- (void)collisionBehavior:(UICollisionBehavior*)behavior beganContactForItem:(id <UIDynamicItem>)item withBoundaryIdentifier:(nullable id <NSCopying>)identifier atPoint:(CGPoint)p;
// Item和碰撞边界结束碰撞时的回调
- (void)collisionBehavior:(UICollisionBehavior*)behavior endedContactForItem:(id <UIDynamicItem>)item withBoundaryIdentifier:(nullable id <NSCopying>)identifier;

@end





#pragma mark - 碰撞行为 Class
#pragma mark -
NS_CLASS_AVAILABLE_IOS(7_0) @interface UICollisionBehavior : UIDynamicBehavior

/* 实例化 */
- (instancetype)initWithItems:(NSArray<id <UIDynamicItem>> *)items NS_DESIGNATED_INITIALIZER;

// 添加碰撞Item
- (void)addItem:(id <UIDynamicItem>)item;
// 移除碰撞Item
- (void)removeItem:(id <UIDynamicItem>)item;

/// 已添加到碰撞行为的Item
@property (nonatomic, readonly, copy) NSArray<id <UIDynamicItem>> *items;
/// 碰撞类型
@property (nonatomic, readwrite) UICollisionBehaviorMode collisionMode;
/// 是否开启系统碰撞边界(即手机屏幕的边界;碰撞标识符为nil;如果collisionMode是UICollisionBehaviorModeItems类型,此效果无效)
@property (nonatomic, readwrite) BOOL translatesReferenceBoundsIntoBoundary;
// 设置自定义碰撞边界(碰撞标识符为nil)
- (void)setTranslatesReferenceBoundsIntoBoundaryWithInsets:(UIEdgeInsets)insets;

// 添加碰撞边界(设置贝塞尔曲线路径为边界)
- (void)addBoundaryWithIdentifier:(id <NSCopying>)identifier forPath:(UIBezierPath *)bezierPath;
// 添加碰撞边界(设置两点之间的线段为边界)
- (void)addBoundaryWithIdentifier:(id <NSCopying>)identifier fromPoint:(CGPoint)p1 toPoint:(CGPoint)p2;
// 返回指定标识符的贝塞尔边界
- (nullable UIBezierPath *)boundaryWithIdentifier:(id <NSCopying>)identifier;
// 移除指定标识符的碰撞边界
- (void)removeBoundaryWithIdentifier:(id <NSCopying>)identifier;

/// 获取已经添加到碰撞边界的标识符
@property (nullable, nonatomic, readonly, copy) NSArray<id <NSCopying>> *boundaryIdentifiers;

// 移除所有碰撞边界
- (void)removeAllBoundaries;

/// 碰撞行为代理
@property (nullable, nonatomic, weak, readwrite) id <UICollisionBehaviorDelegate> collisionDelegate;

@end





NS_ASSUME_NONNULL_END

#else
#import <UIKitCore/UICollisionBehavior.h>
#endif