1.9動(dòng)力學(xué)元素UIDynamicItemBehavior自身屬性
(一)動(dòng)力學(xué)元素UIDynamicItemBehavior作用
UIDynamicItemBehavior作用:是一個(gè)輔助行為,用來(lái)設(shè)置動(dòng)力學(xué)元素參與物理仿真過(guò)程中的參數(shù),如:彈性系數(shù),摩擦系數(shù),密度,阻力,角阻力,以及是否允許旋轉(zhuǎn)等.
(二)UIDynamicItemBehavior常用屬性和方法
@property (nonatomic, readonly, copy) NSArray<id <UIDynamicItem>> *items;
// 彈性系數(shù),決定了碰撞時(shí)的彈性程度
@property (readwrite, nonatomic) CGFloat elasticity; // Usually between 0 (inelastic) and 1 (collide elastically)
// 摩擦系數(shù),決定了延接觸面平滑時(shí)的摩擦力有多大
@property (readwrite, nonatomic) CGFloat friction; // 0 being no friction between objects slide along each other
// 密度,根size結(jié)合使用,計(jì)算物體的總質(zhì)量,質(zhì)量越大物體減速或加速越困難.
@property (readwrite, nonatomic) CGFloat density; // 1 by default
// 阻力,決定線性移動(dòng)的阻力大小,和摩擦系數(shù)不同,摩擦系數(shù)只作用于摩擦運(yùn)動(dòng)
@property (readwrite, nonatomic) CGFloat resistance; // 0: no velocity damping
// 角阻力 ,決定旋轉(zhuǎn)運(yùn)動(dòng)時(shí)的阻力
@property (readwrite, nonatomic) CGFloat angularResistance; // 0: no angular velocity damping
// 是否允許旋轉(zhuǎn) 在真是物理環(huán)境中是沒(méi)有的.為NO時(shí)無(wú)論施加到物體上面是什么都不會(huì)動(dòng)
@property (readwrite, nonatomic) BOOL allowsRotation; // force an item to never rotate
// 初始化一個(gè)UIDynamicItemBehavior
- (instancetype)initWithItems:(NSArray<id <UIDynamicItem>> *)items;
// 添加一個(gè)動(dòng)力學(xué)元素
- (void)addItem:(id <UIDynamicItem>)item;
// 移除一個(gè)動(dòng)力學(xué)元素
- (void)removeItem:(id <UIDynamicItem>)item;
