this class is not key value coding-compliant for the key managedObjectContext

Ben Coffman — Mon, 28 Sep 2009 16:55:19 GMT

Error Readout:
1st Error:
this class is not key value coding-compliant for the key managedObjectContext

2nd Error:
NSImageCell's object value must be an NSImage

Fix:
1st Error:
There is one prominent reason you could get this answer. You didn't spell your property correctly when you were binding it to....well....whatever you want to bind it to, in my case it was an Array Controller.

My problem however had nothing to do with this. When I created a new project after I upgraded to xCode 3.2 I forgot to check one very import checkbox, Create document-based application (Note: it was not a check box in older version of xCode it was a full icon selection upon creating a project). By not checking this I created a big variety of problems for myself. One of the errors occurring when I didn't check the Create document-based application, was the error this class is not key value coding-compliant for the key managedObjectContext.

2nd Error:
This error is very clear in it's issue. I was creating an entity with a property of native type binary and the compiler wanted NSImage. Grrr but I should be able to pass an image as a binary object, I would say to myself as I had urges to break my laptop and anything else in reach over my knee. My fix again was to simply create a project and remember to click Create document-based application. I know this is not your typical fix, but in case someone else runs into this issue the same way I did I hope they find this and it will be a quick and easy resolution.

Explanation:
All of this pain could have been resolved from the very beginning had I known to click Create document-based application. It was a silly little mistake that cost me a few hours. In my defense however I was under the impression of not checking Create document-based because in Hillegass's book he states that for this exercise we will not be using NSDocument, but NSPersistentDocument instead. It turns out this still means you have to check Create document-based application.

I will state that I should have known something was wrong when I didn't have a MyDocument.xib in the Resource folder after I created the project.

I've attached an image, mainly because blog posts are more fun when there is an image, but also because it shows where this one simple little check box changed my life for a hot minute.

Mac OS X Snow Leopard

Ben Coffman — Sun, 30 Aug 2009 20:10:00 GMT

Snow Leopard has only been out since Friday, but a few people got the OS upgrade early and blogged all the good stuff. Knowing this, I'm still going to blog about the new OS from Apple.

I'll cover the price, the security upgrade, the cool new features, the size reduction and make a fun little video demonstrating some of the features in Snow Leopard.

$29 dollars. The low price is largely because Snow Leopard is more of an upgrade than a whole new OS. It offers only a few new flashy features that mac users have come to expect. Most of its added features are in unseen functionality such as Grand Central Dispatch, that most will never see or care about. Just knowing their computer runs faster is good enough. Examining these aspects Apple marketing said $29 bucks is a fair price. I agree, skip a few drinks this weekend and you have your new upgrade.

Security has always been a big aspect enthusiast place on Apple vs. Windows. Sadly even with this new upgrade, Snow Leopard is not as secure Windows 7. Windows 7 has some new security functionality, such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP). Elinor Mills wrote a great article on it here. The real question about Max OS X security: does Apple need to have the latest security practices incorporated into their OS? If their OS isn't being targeted, yet, why put a large costly focus on having the newest security practices when it doesn't reduce any potential threats on their OS. This is a small advantage Apple has by having 5% market share next to Windows world domination market share.
SIDE NOTE: This will most likely be changing with future generations, have you seen a college lecture hall these days, it looks like a glowing apple orchard.

Finally the upgrade has the potential to reduce the size of the OS's footprint on your hard drive up to half in some cases. Curiosity has me wondering how they did such dramatic size reductions while still adding functionality.

bencoffman.com/blog - Snow Leopard

this class is not key value coding-compliant for the key managedObjectContext

Mac OS X Snow Leopard