On Sep 18, 2008, at 4:59 PM, Dave DeLong wrote:
On Sep 18, 2008, at 3:57 PM, Rick Mann wrote:
I see that NSObject (and its protocol) define -isEqual: and -
isEqualTo:. What's the difference? Why does something like
NSArray's -indexOfObject: use -isEqual: and not -isEqualTo:? So
that someone can redefine these for an existing class? Why does -
isEqualTo: even exist?
IIRC, isEqual: compares memory addresses, whereas isEqualTo:
compares hashes of the objects being compared. I also believe that
isEqual: is the preferred method.
Nope. isEqual: asks the object to compare itself to another. The
default implementation just uses identity (pointer comparison), but
many subclasses use value comparison or whatever is appropriate.
isEqualTo: is used for scripting support. By default, it's equivalent
to isEqual:, but a class can override it to perform different
scripting-specific comparison.
Cheers,
Ken
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