Converting between multiple image formats in Objective-C

Question

I want to be able to, being given a path to an image, convert that image into another image, but with a different format. By format I mean .png, .bmp .jpg .tiff, etc. In pse

Answer 1

Allright, so with Peter's help I could figure this out. First, if you're working with image paths, then open directly the file with NSData like so:

NSData* imgData = [NSData dataWithContentsOfFile: filePath];

If you're working with NSImage objects and is difficult for you to have the path (for example with an NSImageView) then do this (image is the NSImage object you have):

NSData* imgData = [image TIFFRepresentation];

Now that you have your image into NSData objects, get it into a NSBitmapImageRep:

NSBitmapImageRep* bitmap = [NSBitmapImageRep imageRepWithData: imgData];

And then get a new NSData object, but with a different format:

NSData* newData = [bitmap representationUsingType: NSPNGFileType properties: nil];
// I used NSPNGFileType as an example, but all the
// types I wanted to convert between (except PDF) are supported

Finally, save that newData into a file:

[newData writeToFile: newPath atomically: YES]

Simple as pie, once you get how it works!

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The support for transparency and size control is not that difficult either:

• The NSImage class provides support for setting image's size (-setSize:)
• The NSImageRep (superclass of NSBitmapImageRep) has the -setAlpha: method

Just call those when you need. +1 for Cocoa!