Get UIView's alpha value during an animation

[tallyho]

Hi, I'm animating an UIImageView (transforms and alpha) and need to be able to pause / resume the animation. Got the tranforms working fine but I've not managed to grab the changing alpha value. Grabbing the UIImageView's alpha (myView.alpha) directly just gives me the before or after value [1.0, 0.0]. For mid-animation transforms I'm accessing the layer's presentation layer to get to its transform ... thought there might be something similar for the changing alpha value but haven't found anything yet.
Any ideas?
Thanks for any help.

[tallyho]

I missed the presentation layer's opacity property ... that holds the current animated alpha value.

Cheers

[Duncan C]

Originally Posted by tallyho

I missed the presentation layer's opacity property ... that holds the current animated alpha value.

Cheers

I've never tried to read the "in flight" value of a view with an animation in progress. Can you post some sample code showing how to get those values?

Can you query the presentation layer while the animation is active?

If you could grab the transform for a rotate/translate/scale, it might even be possible to do hit testing of touches on a view that's mid-animation, which is something I didn't think was practical (For a crude hit test I would get the transform for the view, then apply that transform to the view's frame.)


Regards,

Duncan C
WareTo

[hello24]

If I remember correctly from one of the Stanford lectures, you don't have access to the intermediate values and you can't change a transition whilst it's running.
From the developer point of view, the view has only 2 states and the final state comes into effect when you commit the animations.

[nesh96]

Originally Posted by tallyho

Hi, I'm animating an UIImageView (transforms and alpha) and need to be able to pause / resume the animation. Got the tranforms working fine but I've not managed to grab the changing alpha value. Grabbing the UIImageView's alpha (myView.alpha) directly just gives me the before or after value [1.0, 0.0]. For mid-animation transforms I'm accessing the layer's presentation layer to get to its transform ... thought there might be something similar for the changing alpha value but haven't found anything yet.
Any ideas?
Thanks for any help.

I am just thinking at the top of my head, so im not sure if it will work.
Try using an NSTimer for your animation and everytime your timer fires it will do an NSLog of the alpha.