macOS Data binding is deprecated?

kainjow said:

Not sure what you mean. You bind to data an NSData object, and you bind to value an NSImage. Since NSImageViews display images and not data objects, it really should be an image, which is probably why Apple deprecated the data binding since it doesn't make sense.

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lordandrei said:

I too came across this problem. However, when I switched the Binding from Data to Value for my NSView, the interface no longer honoured the "Selection." Now whichever image I drag to the interface becomes the image for all selections in the array.

If I bind to Data, things work correctly, but I get the deprecation warning.

Suggestions?

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1. Create a new class called DataImageTransformer, following the examples in the above-linked Value Transformer Programming Guide. Specifically, for the 'transformedValue:' implementation, I check to make sure that the input is a kind of NSData instance, and then use it to initialize an NSImage instance, which I return. For the 'reverseTransformedValue:' implementation, I check to make sure that the input is a kind of NSImage, then use the 'TIFFRepresentation' instance method to generate an NSData instance, which I return. There are ways to get other kinds of representations (JPG, PNG, etc.), but those are more involved.
2. Create a new class called AppDelegate, instantiate it in Interface Builder, and set the new instance as the Application's delegate. In AppDelegate.m, implement the 'initialize' class method according to the instructions in the section "Registering a Value Transformer" of the above-linked guide. It'll look something like the following:
   
   Code:

   #import "DataImageTransformer.h"
   
   + (void)initialize {
       DataImageTransformer *dit = [[[DataImageTransformer alloc] init] autorelease];
       [NSValueTransformer setValueTransformer:dit forName:@"DataToImageTransformer"];
   }

3. In InterfaceBuilder, select the NSImageView, bring up the Bindings inspector palette, disable the 'data' binding (if enabled) and instead bind the 'value' binding, just like the book says to do for the 'data' binding. The one difference is that you're also going to fill in the "Value Transformer" field with the name that you registered the DataImageTransformer instance under in the 'initialize' method (in my example it would be "DataToImageTransformer").

zbrimhall said:

Specifically, for the 'transformedValue:' implementation, I check to make sure that the input is a kind of NSData instance, and then use it to initialize an NSImage instance, which I return. For the 'reverseTransformedValue:' implementation, I check to make sure that the input is a kind of NSImage, then use the 'TIFFRepresentation' instance method to generate an NSData instance, which I return.

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Blakadher said:

I ended up just not implementing that check, but I know that is not good coding practice so I've been searching for how to check that the value object passed to those 2 methods is of the correct type. My Google-fu is failing me and I've not found the proper way to do that. Can anyone give me a pointer? Thanks.

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zbrimhall said:

The problem is of course that your managed object's photo is returned as an instance of NSData, while the 'value' binding on NSImageView expects an instance of NSImage. In order to avoid the deprecation warning and bind to 'value' you need to have a middleman in there somewhere, handling the conversion between NSData and NSImage.

Enter value transformers.
...

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CocoaBean said:

Hi,

After finishing the example from Hillegass' book chapter 11 (core data), I debug the app and get the following warning: The "data" binding is deprecated in Mac OS X versions 10.6 and later.

This is related to binding the imageWell under the data binding. If the data binding is indeed deprecated then what do I use?

Had a search and can't find what I'm after.

Thanks

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