Use the Binary type for binary data, data you wouldn't be able to display in a text editor. Audio and video data are examples of data that could use the Binary type.
Use the Transformable type for any data type that is not in the list of Core Data types. If you have any custom data types in your app that you want to use with Core Data, give that attribute the Transformable type. Rich text is a common example of a Transformable type. Core Data has the String type for plain type but nothing built-in for rich text.
Attributes with the Transformable type are converted to and from the NSData (Swift may call this type Data) type.
The article at the following link provides more information about the Transformable and Binary types:
geekyviney.blogspot.com/2015/02/transformable-binary-data-properties-in.html
