How can I change every color in a UIImage to gray? [closed]

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Closed 8 years ago.

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I'm trying to create a mask from an image with a transparent background. I want to create a new UIImage where any pixel that has > 0 alpha to turn gray.

Answer 1

You can load an image with rendering mode UIImageRenderingModeAlwaysTemplate which draws the image as a template image, ignoring its color information.

[[UIImage imageNamed:imageName] imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];

Then set the tintColor of the container to gray

yourImageView.tintColor = [UIColor grayColor];