how to convert UIImage to 8 bits 3 channel and 8 bits 1 channel for (image processing) in iOS

I am working on image processing where I have to convert the UIImage to (8 bit 3 channel) and (8 bit 1 channel) in iOS ... I am looking for tutorial over internet but could not find that

Any help would be appreciated

how to convert UIImage to 8 bits 3 channel and 8 bits 1 channel for (image processing) in iOS
 
 
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