UIDynamicItemBehavior 定义的都是一些辅助行为
//
// UIDynamicItemBehavior.h
// UIKit
//
// Copyright (c) 2012-2015 Apple Inc. All rights reserved.
//
#import <Foundation/Foundation.h>
#import <UIKit/UIDynamicBehavior.h>
NS_ASSUME_NONNULL_BEGIN
NS_CLASS_AVAILABLE_IOS(7_0) @interface UIDynamicItemBehavior : UIDynamicBehavior
- (instancetype)initWithItems:(NSArray<id <UIDynamicItem>> *)items NS_DESIGNATED_INITIALIZER;
- (void)addItem:(id <UIDynamicItem>)item;
- (void)removeItem:(id <UIDynamicItem>)item;
@property (nonatomic, readonly, copy) NSArray<id <UIDynamicItem>> *items;
@property (readwrite, nonatomic) CGFloat elasticity; // Usually between 0 (inelastic) and 1 (collide elastically)
@property (readwrite, nonatomic) CGFloat friction; // 0 being no friction between objects slide along each other
@property (readwrite, nonatomic) CGFloat density; // 1 by default
@property (readwrite, nonatomic) CGFloat resistance; // 0: no velocity damping
@property (readwrite, nonatomic) CGFloat angularResistance; // 0: no angular velocity damping
/*!
Specifies the charge associated with the item behavior. Charge determines the degree to which a dynamic item is affected by
electric and magnetic fields. Note that this is a unitless quantity, it is up to the developer to
set charge and field strength appropriately. Defaults to 0.0
*/
@property (readwrite, nonatomic) CGFloat charge NS_AVAILABLE_IOS(9_0);
/*!
If an item is anchored, it can participate in collisions, but will not exhibit
any dynamic response. i.e. The item will behave more like a collision boundary.
The default is NO
*/
@property (nonatomic, getter = isAnchored) BOOL anchored NS_AVAILABLE_IOS(9_0);
@property (readwrite, nonatomic) BOOL allowsRotation; // force an item to never rotate
// The linear velocity, expressed in points per second, that you want to add to the specified dynamic item
// If called before being associated to an animator, the behavior will accumulate values until being associated to an animator
- (void)addLinearVelocity:(CGPoint)velocity forItem:(id <UIDynamicItem>)item;
- (CGPoint)linearVelocityForItem:(id <UIDynamicItem>)item;
// The angular velocity, expressed in radians per second, that you want to add to the specified dynamic item
// If called before being associated to an animator, the behavior will accumulate values until being associated to an animator
- (void)addAngularVelocity:(CGFloat)velocity forItem:(id <UIDynamicItem>)item;
- (CGFloat)angularVelocityForItem:(id <UIDynamicItem>)item;
@end
NS_ASSUME_NONNULL_END
