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Editorial Team
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Asked: 2026-05-28T03:41:42+00:00

I’m trying to achieve a sort of dynamic UIView masking effect. Here is a

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I’m trying to achieve a sort of dynamic UIView masking effect. Here is a sketch:
enter image description here

So as you can see, I’m trying to create a UIView that can effectively cut through an image to reveal the image behind it. I already know how to return an image with a mask statically, however I would like the “revealer” to be draggable (I’ll use pan gesture) and live.

Does anyone have any ideas or starting points on how to achieve this? Thanks

(NOTE: My demo says White layer, but I’d actually like to show another image or photo).

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1 Answer

  1. Editorial Team

    masking an image is not that difficult.

    This link shows the basics.
    http://iosdevelopertips.com/cocoa/how-to-mask-an-image.html

    But personally I think i would make 2 UIImage views and crop the content of the draggable UIView. I’m not sure but I would expect that clipping and panning the second image will be less computationally expensive then applying the mask and will get you a better frame rate.

    So I would do: UIImageView of the full image. A UIView on top of it with a white and some transparency setting to make it look white, then a UIImageView with the image either places or cropped so that only the correct section is showing.

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