I have two questions about coredata custom accessors, I've been reading the
section about them, here's the code suggested for the setter of a property of
type NSRect, in this instance the NSRect is cached in a local instance variable
in the class.
- (void)setBounds:(NSRect)aRect
{
[self willChangeValueForKey:@"bounds"];
bounds = aRect;
[self didChangeValueForKey:@"bounds"];
NSString *rectAsString = NSStringFromRect(aRect);
[self setValue:rectAsString forKey:@"boundsAsString"];
}
Assuming I don't cache the object in an instance variable in the class, because
in my case I don't really need to, I can calculate it on the fly and do not
expect that to be a performance issue, should the willChangeValueForKey: and
didChangeValueForKey: calls bracket the entire method so the setters of the
underlying attributes (the persistent ones) are complete before the call to
didChangeValueForKey:? My concern here is that the didChangeValueForKey: method
could trigger something to go read the transient property, but if I've not set
the underlying persistent properties yet, it won't work. Or should you not nest
like that and I should set the persistent variables first, then call
willChange.. and didChange... afterwards with nothing between them?
Other question is, why do we have to use the setValue:<value> forKey: instead
of just invoking [ self setBoundsAsString: ].
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