Re: KVO Setting a flag for any property change
Re: KVO Setting a flag for any property change
- Subject: Re: KVO Setting a flag for any property change
- From: Keary Suska <email@hidden>
- Date: Wed, 14 Dec 2011 08:56:32 -0700
On Dec 14, 2011, at 6:29 AM, Andre Masse wrote:
> I have a superclass which has a "modified" BOOL property and a bunch of subclasses based on it. When any property is changed, I need to set this flag to YES. I can either write a setter for all properties and set this flag there, or observe all properties and set the flag in -observeValueForKeyPath. Both approach involve a lot of boilerplate coding (some subclasses have 20+ properties).
>
> I thought about using -keyPathsForValuesAffectingModified: but I don't see how I can set a flag using this.
This kind of approach is probably best unless you can base your superclass on NSManagedObject, which does this automatically. But, as you find, there is some difficulty. I would have a pseudo-flag, say "hasBeenModified", and implement +keyPathsForValuesAffectingHasBeenModified:. In -hasBeenModified simply set the flag KVO-compliantly. You mat want to check the flag to avoid unnecessary KVO calls.
HTH.
Keary Suska
Esoteritech, Inc.
"Demystifying technology for your home or business"
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