Question

我创建了这个代码来创建CAKeyframeAnimation，但结果并没有反弹

-(CAKeyframeAnimation *)keyframeBounceAnimationFrom:(NSValue *)from
                                                    to:(NSValue *)to
                                         forKeypath:(NSString *)keyPath
                                       withDuration:(CFTimeInterval)duration
{

    CAKeyframeAnimation * animation = [CAKeyframeAnimation animationWithKeyPath:keyPath];

    NSMutableArray * valuesArray = [NSMutableArray array];
    NSMutableArray * timeKeyArray = [NSMutableArray array];

    [self createBounceFrom:from to:to Values:valuesArray keyTimes:timeKeyArray];

    [animation setValues:valuesArray];
    [animation setKeyTimes:timeKeyArray];

    animation.duration = duration;
    return animation;
}

-(void)createBounceFrom:(NSValue *)from to:(NSValue *)to Values:(NSMutableArray *)values keyTimes:(NSMutableArray *)keyTimes
{

    CGPoint toPoint= [to CGPointValue];
    CGFloat offset = 60;
    CGFloat duration = 1.0f;
    NSUInteger numberOfOscillations= 4;


    [values addObject:from];
    [keyTimes addObject:[NSNumber numberWithFloat:0.0f]];
    //============
    //ideally bouncing will depend from starting position to end poisiton as simulating real Dumping Oscillations
    //============

    for (NSUInteger index= 0; index <numberOfOscillations ; index++)
    {


        CGPoint viaPoint = CGPointMake(toPoint.x,  toPoint.y + offset);
        NSValue * via = [NSValue valueWithCGPoint:viaPoint];
        [values addObject:via];
        //add time consumed for each oscillation
        [keyTimes addObject:[NSNumber numberWithFloat:duration]];
       // duration = duration - 0.1;

        offset = - offset ;
    }

    [values addObject:to];
    [keyTimes addObject:[NSNumber numberWithFloat:0.6]];

}

Answer 1

以下是一些很好的链接，其中包含一些如何使用它的示例：

（经过一番观察之后我发现了这个：http://www.cocoanetics.com/2012/06/lets-bounce/我觉得它反弹得更好，但更高级。所以不要把代码放在这里）

http://www.touchwonders.com/some-techniques-for-bouncing-animations-in-ios/

CAKeyframeAnimation的示例是:(取自链接）

-(void)animateGreenBall
{
    NSValue * from = [NSNumber numberWithFloat:greenBall.layer.position.y];
    CGFloat bounceDistance = 20.0;
    CGFloat direction = (greenUp? 1 : -1);

    NSValue * via = [NSNumber numberWithFloat:(greenUp ? HEIGHT_DOWN : HEIGHT_UP) + direction*bounceDistance];
    NSValue * to = greenUp ? [NSNumber numberWithFloat:HEIGHT_DOWN] : [NSNumber numberWithFloat:HEIGHT_UP];
    NSString * keypath = @"position.y";
    [greenBall.layer addAnimation:[self keyframeBounceAnimationFrom:from via:via to:to forKeypath:keypath withDuration:.6] forKey:@"bounce"];
    [greenBall.layer setValue:to forKeyPath:keypath];
    greenUp = !greenUp;
}

-(CAKeyframeAnimation *)keyframeBounceAnimationFrom:(NSValue *)from 
                                                via:(NSValue *)via 
                                                 to:(NSValue *)to 
                                         forKeypath:(NSString *)keyPath 
                                       withDuration:(CFTimeInterval)duration
{
    CAKeyframeAnimation * animation = [CAKeyframeAnimation animationWithKeyPath:keyPath];
    [animation setValues:[NSArray arrayWithObjects:from, via, to, nil]];
    [animation setKeyTimes:[NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0], [NSNumber numberWithFloat:.7], [NSNumber numberWithFloat:1.0], nil]];

    animation.duration = duration;
    return animation;
}

如何使用CAKeyframeAnimation用于Bouncing effect IOS

1 个答案: