Does anybody know how to change the brightness of a UIImageView in objective-C? Also, is there a way to increase/decrease the size of the UIImage?
Check out the UIImage (void)drawInRect:(CGRect)rect blendMode:(CGBlendMode)blendMode alpha:(CGFloat)alpha method and see what you can create. Otherwise, you are going to have to do some more in depth work increasing the brightness of each pixel in HSV color space (proportionately increasing the V values). By blending the image with a white image using the right blend mode though, you should be able to brighten the UIImage contained within the UIImageView.
EDIT:
Also, as I answered in your other question, the UIImage will scale to fit the UIImageView. The image data itself will not scale, but the onscreen rendering will.
来源：https://stackoverflow.com/questions/7219050/increase-decrease-brightness-of-a-uiimageview