Animating a UIView without using CoreAnimation

Asked Mar 13 '13 at 19:28

Active Mar 13 '13 at 19:28

Viewed 168 times

I'm trying to move a UIVIew across the screen. I don't want to use CoreAnimation because I need to be able to vary the velocity of the view in real-time.

At the moment I have the following hierarchy:

UIView
-- UIView (subview)

I'm sub-classing the parent view and adding an update method.

-(void) update: (float) dt {

    float newX = _subView.transform.tx + dt * dxdt;

    [_subView setTransform: CGAffineTransformMakeTranslation(newX, 0)];
}

The update method is called every frame and I was hoping that this would cause the sub view to be animated.

Unfortunately it doesn't move. I've tried:

[_subView setNeedsDisplay]

But it still doesn't work. There must be something I'm missing to force the view to re-draw.

asked Mar 13 '13 at 19:28

James Andrews

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Are you using auto layout? – rdelmar Mar 13 '13 at 19:30
Autolayout is disabled. – James Andrews Mar 13 '13 at 19:31
What do you mean, "the update method is called every frame"? How are you calling this method? – rdelmar Mar 13 '13 at 19:37
It's called from a separate thread i.e. 60 times per second – James Andrews Mar 13 '13 at 19:38
3

Don't ever change properties of views from a separate thread, UIKit is *not* thread-safe. – omz Mar 13 '13 at 19:41
How would you recommend I animate the view in that case? I need to be able to change the view's velocity in real time. – James Andrews Mar 13 '13 at 19:42
I would do it by turning on auto layout, and animating one of the constraints using a CADisplayLink for the timing. – rdelmar Mar 13 '13 at 19:46
What you're trying to do can be accomplished with Core Animation. You should look at creating a custom timing function. Take a look here: http://stackoverflow.com/questions/5161465/how-to-create-custom-easing-function-with-core-animation – Matt Long Mar 14 '13 at 18:27

Animating a UIView without using CoreAnimation

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