Clear image with fade border

Question

I have two UIImageView with same frame. One imageView above second imageView now I'm erasing upper imageView using Core Graphics. My problem is that the border of eraser is very sharp I want faded border i.e. after erasing the upper image should match the lower one's pallet. See below example -

I used these two images and below is result -


As you can see in this image eraser's border is very sharp. I want to make it faded out like in the middle it should be dark then light then more light and so on i.e. we cant see the width and end of brush. And here is my - My Sample Code
Let me know if my question is not clear enough.

Answer 1

You can have a png image like brush (dark in the middle and light in the corner) and draw the image over your image like this.

        [eraser drawAtPoint:location blendMode:kCGBlendModeDestinationOut alpha:1];