Animate a UIImageView in the middle of an animation

Question

I have an object that is moving right to left across the screen:

[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:7.8];
[UIView setAnimationCurve:UIViewAnimationCurveLinear];
 myImageview.layer.position = CGPointMake(20,  myImageView.layer.position.y);
[UIView commitAnimations];

I found out that even while the animation is still happening, XCode already marks the image's location as its final destination, and in order to detect a touch on the moving image, I need to use the presentationLayer:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesBegan:touches withEvent:event];

    UITouch *touch = [touches anyObject];
    CGPoint touchPoint = [touch locationInView:self.view];

    if ([myImageview.layer.presentationLayer hitTest:touchPoint]) {
        NSLog(@"it's a hit!");
    }
}

This part works. Now, I'd like the image to move up when it is pressed. I want the image to move up while it continues it's sideways movement. Instead, this code moves the image not just up, but also all the way to its final destination on the left:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesBegan:touches withEvent:event];

    UITouch *touch = [touches anyObject];   
    CGPoint touchPoint = [touch locationInView:self.view];

    if ([mouse.layer.presentationLayer hitTest:touchPoint]) {
        NSLog(@"it's a hit!");
        [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:0.5];
        [UIView setAnimationCurve:UIViewAnimationCurveLinear];
        myImageView.layer.position = CGPointMake( mouse.layer.position.x,  myImageView.layer.position.y - 40);
        [UIView commitAnimations];
    }
}

I want the image to move up while it continues it's sideways movement. Does anyone know of a way to accomplish this?

Thanks so much!

Adam Eberbach · Accepted Answer · 2012-10-03T06:16:55.387

Have you tried setting the animation option UIViewAnimationOptionBeginFromCurrentState?

(I say option because it is an option in the block-based animation methods introduced with iOS 4. It is also available as [UIView setAnimationBeginsFromCurrentState:YES] if you can't switch away from the deprecated UIView class methods just yet.)

touchesBegan becomes (using block animations):

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    [super touchesBegan:touches withEvent:event];

    UITouch *touch = [touches anyObject];   
    CGPoint touchPoint = [touch locationInView:self.view];

    if ([mouse.layer.presentationLayer hitTest:touchPoint]) {
        NSLog(@"it's a hit!");
        [UIView animateWithDuration:0.5 delay:0.0 options:(UIViewAnimationOptionCurveLinear & UIViewAnimationOptionBeginFromCurrentState) animations:^{
            myImageView.layer.position = CGPointMake( myImageView.layer.position.x,  mouse.layer.position.y - 40);
        }completion:^(BOOL complete){
            //
        }];
    }
}

If you use that you should be able to specify the final x and y coordinates you want and have animation proceed from the point at which the object was touched to that position.

Very interesting, it takes over instead of the previous animation. I was trying to get the original animation to continue since it only affected the x-axis and add on an animation to the y-axis along the way. This is definitely an interesting option, but still won't work as is, because it not only moves my imageView up but also sends it to the final destination on the left. Thanks so much! Will play around with this new option. =) — RanLearns, Oct 03 '12 at 06:35
You do need to recalculate and change animation parameters to get the final result you want. — Adam Eberbach, Oct 03 '12 at 06:37

Animate a UIImageView in the middle of an animation

1 Answers1