iOS核心动画 - 关键帧动画

• 简单介绍

是CApropertyAnimation的子类，跟CABasicAnimation的区别是：CABasicAnimation只能从一个数值(fromValue)变到另一个数值(toValue)，而CAKeyframeAnimation会使用一个NSArray保存这些数值

• 属性解析：

• values：就是上述的NSArray对象。里面的元素称为”关键帧”(keyframe)。动画对象会在指定的时间(duration)内，依次显示values数组中的每一个关键帧

• path：可以设置一个CGPathRef\CGMutablePathRef,让层跟着路径移动。path只对CALayer的anchorPoint和position起作用。如果你设置了path，那么values将被忽略

• keyTimes：可以为对应的关键帧指定对应的时间点,其取值范围为0到1.0,keyTimes中的每一个时间值都对应values中的每一帧.当keyTimes没有设置的时候,各个关键帧的时间是平分的

• 说明：CABasicAnimation可看做是最多只有2个关键帧的CAKeyframeAnimation

• Values方式：

• CAKeyframeAnimation *animation = [CAKeyframeAnimation animation];
  animation.keyPath = @"position";
  NSValue *value1=[NSValue valueWithCGPoint:CGPointMake(100, 100)];
  NSValue *value2=[NSValue valueWithCGPoint:CGPointMake(200, 100)];
  NSValue *value3=[NSValue valueWithCGPoint:CGPointMake(200, 200)];
  NSValue *value4=[NSValue valueWithCGPoint:CGPointMake(100, 200)];
  NSValue *value5=[NSValue valueWithCGPoint:CGPointMake(100, 100)];
  animation.values=@[value1,value2,value3,value4,value5]; animation.repeatCount=MAXFLOAT;
  animation.removedOnCompletion = NO;
  animation.fillMode = kCAFillModeForwards;
  animation.duration = 4.0f;
  animation.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
  animation.delegate=self;
  [self.myView.layer addAnimation:animation forKey:nil];

• Path方式：

• CAKeyframeAnimation *animation = [CAKeyframeAnimation animation];
  animation.keyPath = @"position";
  CGMutablePathRef path=CGPathCreateMutable();
  CGPathAddEllipseInRect(path, NULL, CGRectMake(150, 100, 100, 100));
  animation.path=path;
  CGPathRelease(path);
  animation.repeatCount=MAXFLOAT;
  animation.removedOnCompletion = NO;
  animation.fillMode = kCAFillModeForwards;
  animation.duration = 4.0f;
  animation.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
  animation.delegate=self;
  [self.myView.layer addAnimation:animation forKey:nil];