如何使用CAKeyframeAnimation是为了弹跳效果IOS
如何使用CAKeyframeAnimation是为了弹跳效果IOS
提问于 2013-01-22 02:48:59
我写了这段代码来创建CAKeyframeAnimation，但是结果一点也没有跳动
-(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]];
}回答 1
Stack Overflow用户
发布于 2013-04-06 22:07:58
这里有一个很好的链接，里面有一些如何使用它的例子：
(经过进一步的研究，我发现了这个：http://www.cocoanetics.com/2012/06/lets-bounce/，我认为它有更好的反弹效果，但也更先进。所以我不会把代码放在这里)
http://www.touchwonders.com/some-techniques-for-bouncing-animations-in-ios/
使用CAKeyframeAnimation的示例是：(取自链接)
-(void)animateGreenBall
{
NSValue *from = @(greenBall.layer.position.y);
CGFloat bounceDistance = 20.0;
CGFloat direction = (greenUp? 1 : -1);
NSValue *via = @((greenUp ? HEIGHT_DOWN : HEIGHT_UP) + direction*bounceDistance);
NSValue *to = greenUp ? @(HEIGHT_DOWN) : @(HEIGHT_UP);
NSString *keyPath = @"position.y";
CAKeyframeAnimation *animation = [self keyframeBounceAnimationFrom:from
via:via
to:to
forKeyPath:keyPath
withDuration:.6];
[greenBall.layer addAnimation:animation 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:@[from, via, to, nil]];
[animation setKeyTimes:@[@(0), @(.7), @(1), nil]];
animation.duration = duration;
return animation;
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/14445229
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