How do I change the alpha value only of a part of an UIImage in Xcode? 

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                    Need more info. What platform, what libraries, what have you tried, and it's not an Xcode question because Xcode is just the IDE. – Almo May 09 '14 at 13:36
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                    [How to set the opacity/alpha of a UIImage?](http://stackoverflow.com/questions/5084845/how-to-set-the-opacity-alpha-of-a-uiimage) – Hemang May 09 '14 at 13:41
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                    @Almo: Thanks. I changed the key words in my question. I have a ball and I try to change the alpha value on only a part of that ball image, as shown in the attached image. – suyama May 09 '14 at 13:42
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                    1You should use alpha masking. This documentation has a lot of examples: https://developer.apple.com/library/mac/documentation/graphicsimaging/conceptual/drawingwithquartz2d/dq_images/dq_images.html – Taum May 09 '14 at 13:45
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                    OK. I'll read about alpha masking. Thanks to all. – suyama May 09 '14 at 13:48
 
    