Creating a Subclass of NSTextStorage
NSTextStorage
isn’t a fully concrete class; rather, it is the abstract superclass of a class cluster. It defines the storage for its NSLayoutManager
objects and implements some methods, but doesn’t provide the primitive attributed string methods to subclasses. A subclass must define the storage for its attributed string, typically as an instance variable of type NSMutableAttributedString
, override init
and define its own initialization methods, and implement the primitive methods of both NSAttributedString
and NSMutableAttributedString
. The primitive methods are:
Beyond these requirements, if a subclass overrides or adds any methods that change its characters or attributes directly, those methods must invoke edited:range:changeInLength:
after performing the change in order to keep the change-tracking information up to date. See the method description for more information.
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