ios - How to make UIView animation sequence repeat and autoreverse

Question

How to make this complex animation repeat and autoreverse? Is there any way to add options UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat to this animation sequence?

   [UIView animateWithDuration:1.0f animations:^{

        someView.frame = someFrame1;

    } completion:^(BOOL finished) {

        [UIView animateWithDuration:0.5f animations:^{

            someView.frame = someFrame2;

        } completion:nil];

    }];

Answer 1

To animation from point 1 to 2 to 3 to 2 to 1 and repeat, you can do use animateKeyframesWithDuration in iOS 7 and later:

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];

If using auto-layout, you can animate the changing of the constraint constants:

[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];

Or, the approach with auto layout is to deactivate the constraints, and then you can animate using frame values or what have you.

---

In earlier versions of iOS, you can use CAKeyframeAnimation, for example to animate along a path:

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"];

You can do this with however many points you want. This also useful technique if you want to animate along a curved path (e.g. a circle or bezier curve).

---

To just animate between two points, you can use animateWithDuration:delay:options:animations:completion:, such as:

[UIView animateWithDuration:0.5
                      delay:0.0
                    options:UIViewAnimationOptionAutoreverse | UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveEaseInOut
                 animations:^{
                     // do whatever animation you want, e.g.,

                     someView.frame = someFrame1;
                 }
                 completion:NULL];

This animates the movement of someView from the starting frame to someFrame1 and back.

By the way, using UIViewAnimationOptionCurveEaseInOut in conjunction with UIViewAnimationOptionAutoreverse and UIViewAnimationOptionRepeat will give you a smoother effect as the animation reverses and repeats.