Continuous animation in iOS?

Question

In my case I have a view with content. I want to scroll this content on UILongPressGestureRecognizer events:

if the touch position y is enough near the up view border then scroll up;
if the touch position y is enough near the bottom view border then scroll down.

I can't simply use scrollView so I used CATransform3D structs and animateWithDuration:... methods. The problem is I don't know how long should I scroll (the duration of the scroll animation). The second problem is animation should be called when the touch position (of long press gesture) is changed - it seems easy but may have influence on the final solution.

How to solve such issue?

Ok, because I use iCarousel. But it has no relation to the question. — Vyachaslav Gerchicov, May 22 '15 at 12:23
Isn't the point of `iCarousel`, like a scroll view, to rotate the content for you? I'm just trying to understand why you're doing the animation yourself rather than using the container, which in this case is the carousel. — Caleb, May 22 '15 at 12:31
you want to keep the animation going as long as user presses onto the view, am i right? — Mert Buran, May 22 '15 at 12:57
almost. I want to keep the animation while user presses onto the view and this touch is in a specific rect (or user pressed and moved his touch to this area) — Vyachaslav Gerchicov, May 22 '15 at 13:27

score 0 · Accepted Answer · answered May 22 '15 at 13:05

I am not sure if I understood your question correctly, here I share a method that listens to longPressRecognizer and animates a view as long as user presses onto that view. As user stops pressing, view animates back to its default state. You can check if user gesture satisfies your position conditions by adding position check statements to if/else if's. Hope that helps.

- (void)longPressed:(UILongPressGestureRecognizer *)recognizer {
    UIView *longPressView = self.longPressView;
    if (recognizer.state == UIGestureRecognizerStateBegan) {
        [UIView animateWithDuration:longPressDuration
                              delay:0.f
                            options:UIViewAnimationOptionCurveLinear|UIViewAnimationOptionBeginFromCurrentState
                         animations:^{
                             //do stuff
                         }
                         completion:^(BOOL finished) {
                             if (finished) {
                                 //long press exceeded time limit: do stuff
                             }
                         }];
    }
    else if (recognizer.state == UIGestureRecognizerStateEnded) {
        [UIView animateWithDuration:longPressDuration/2.0
                              delay:0.f
                            options:UIViewAnimationOptionCurveEaseInOut|UIViewAnimationOptionBeginFromCurrentState
                         animations:^{
                             //do stuff
                         }
                         completion:nil];
    }
}

1)You didn't understand the question. The animation should start on `UIGestureRecognizerStateChanged` event too. With your code it works as if the whole is acceptable. But I have 2 areas and so touch may not only began/end in this area, it also may enter/exit this area after `UIGestureRecognizerStateBegan`. 2)why do you use `if (finished)`? I ask because this completion block will be called on device rotation with `finished == NO` and so the code in this block may never be executed. — Vyachaslav Gerchicov, May 22 '15 at 13:34
what you need is not UILongPressGestureRecognizer. Please have a look at UIPanGestureRecognizer. — Mert Buran, May 22 '15 at 13:51
Explain me why I need `UIPanGestureRecognizer`. In my case UILongPressGesture seems more appropriate. — Vyachaslav Gerchicov, May 22 '15 at 14:04

Continuous animation in iOS?

1 Answers1