Get underlying NSData from UIImage

Question

I can create UIImage from NSData using [UIImage imageWithData:] or [UIImage initWithData:] methods.

I wonder if I can get the NSData back from an existing UIImage? Something on the line of NSData *myData = [myImage getData];

Answer 1

NSData *imageData = UIImageJPEGRepresentation(image, 0.7); // 0.7 is JPG quality 

or

NSData *imageData = UIImagePNGRepresentation(image); 

Depending if you want your data in PNG format or JPG format.

Answer 2

When initialising a UIImage object with init(data: originalData), that originalData will be converted into raw data in some kind of internal format. These data can be retrieved later with

let rawData = myImage.cgImage?.dataProvider?.data as Data? 

However because the rawData is raw, it is going to be even larger than when using UIImagePNGRepresentation.