一丶原文

#import <pop/POPAnimatableProperty.h>
#import <pop/POPAnimation.h>

/**
 @abstract Flags for clamping animation values.
 @discussion Animation values can optionally be clamped to avoid overshoot. kPOPAnimationClampStart ensures values are more than fromValue and kPOPAnimationClampEnd ensures values are less than toValue.
 */
typedef NS_OPTIONS(NSUInteger, POPAnimationClampFlags)
{
  kPOPAnimationClampNone        = 0,
  kPOPAnimationClampStart       = 1UL << 0,
  kPOPAnimationClampEnd         = 1UL << 1,
  kPOPAnimationClampBoth = kPOPAnimationClampStart | kPOPAnimationClampEnd,
};

/**
    semi-concrete 属性动画子类
 */
@interface POPPropertyAnimation : POPAnimation

/**
做动画的属性
 */
@property (strong, nonatomic) POPAnimatableProperty *property;

/**
做动画的初始值;
如果未设置,则在动画启动的时候,按照对象当前的值作为初始值;
 */
@property (copy, nonatomic) id fromValue;

/**
做动画的值
如果未设置,则在动画启动的时候,按照对象当前的值作为初始值;
 */
@property (copy, nonatomic) id toValue;

/**
 四舍五入系数;
 作用让动画变得更圆滑; 默认0; 取1.0和取整值之间;
 */
@property (assign, nonatomic) CGFloat roundingFactor;

/**
 就是让动画保证在fromValue和tovalue之间,不会越界;
 */
@property (assign, nonatomic) NSUInteger clampMode;

/**
动画的值是叠加,而不是设置;
默认NO;
 */
@property (assign, nonatomic, getter = isAdditive) BOOL additive;

@end

二问题

1.@property (assign, nonatomic) CGFloat roundingFactor; 使用;

先看看源码;

默认为0
 roundingFactor(0),

继续翻

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四舍五入;

就是让每一帧动画变得更滑一点;

@property (assign, nonatomic) NSUInteger clampMode;

庆幸是开源的,不然压根不懂它干嘛的;

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让动画保证在fromValue和tovalue之间,不会越界
看枚举

  kPOPAnimationClampNone        = 0,
  kPOPAnimationClampStart       = 1UL << 0, //保证fromValue开始
  kPOPAnimationClampEnd         = 1UL << 1,//保证toValue开始
  kPOPAnimationClampBoth = kPOPAnimationClampStart | kPOPAnimationClampEnd,

@property (assign, nonatomic, getter = isAdditive) BOOL additive;

叠加,不是设置;

图片来源:http://www.tuicool.com/articles/v22QVfq

1.gif

三丶其他:

翻译有问题,留言告诉我下,谢谢;
以及有使用问题也可以留言,一起探讨探讨;