要从点 1 到 2 到 3 到 2 到 1 动画并重复,您可以在 iOS 7 及更高版本中使用animateKeyframesWithDuration:
someView.frame = frame1;
[UIView animateKeyframesWithDuration:2.0 delay:0.0 options:UIViewKeyframeAnimationOptionAutoreverse | UIViewKeyframeAnimationOptionRepeat animations:^{
[UIView addKeyframeWithRelativeStartTime:0.0 relativeDuration:0.5 animations:^{
someView.frame = frame2;
}];
[UIView addKeyframeWithRelativeStartTime:0.5 relativeDuration:0.5 animations:^{
someView.frame = frame3;
}];
} completion:nil];
如果使用自动布局,您可以动画约束常量的变化:
[UIView animateKeyframesWithDuration:2.0 delay:0.0 options:UIViewKeyframeAnimationOptionAutoreverse | UIViewKeyframeAnimationOptionRepeat animations:^{
[UIView addKeyframeWithRelativeStartTime:0.0 relativeDuration:0.5 animations:^{
topConstraint.constant = 200;
leftConstraint.constant = 200;
[self.view layoutIfNeeded];
}];
[UIView addKeyframeWithRelativeStartTime:0.5 relativeDuration:0.5 animations:^{
topConstraint.constant = 100;
leftConstraint.constant = 300;
[self.view layoutIfNeeded];
}];
} completion:nil];
或者,自动布局的方法是停用约束,然后您可以使用 frame 值或您拥有的值进行动画处理。
在早期版本的 iOS 中,您可以使用 CAKeyframeAnimation,例如沿路径制作动画:
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(100.0, 100.0)];
[path addLineToPoint:CGPointMake(200.0, 200.0)];
[path addLineToPoint:CGPointMake(100.0, 300.0)];
CAKeyframeAnimation *animatePosition = [CAKeyframeAnimation animationWithKeyPath:@"position"];
animatePosition.path = [path CGPath];
animatePosition.duration = 1.0;
animatePosition.autoreverses = YES;
animatePosition.repeatCount = HUGE_VALF;
[self.someView.layer addAnimation:animatePosition forKey:@"position"];
您可以使用任意数量的点来执行此操作。如果您想沿曲线路径(例如圆形或贝塞尔曲线)制作动画,这也是有用的技术。
如果只是在两点之间做动画,可以使用animateWithDuration:delay:options:animations:completion:,如:
[UIView animateWithDuration:0.5
delay:0.0
options:UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveEaseInOut
animations:^{
// do whatever animation you want, e.g.,
someView.frame = someFrame1;
}
completion:NULL];
这将动画someView 从起始帧移动到someFrame1 并返回。
顺便说一句,将UIViewAnimationOptionCurveEaseInOut 与UIViewAnimationOptionAutoreverse 和UIViewAnimationOptionRepeat 结合使用会在动画反转和重复时为您提供更平滑的效果。