bencoffman.com/blog - Mac OS X

When to use the * (star) with Objective C

Ben Coffman — Sat, 12 Jun 2010 15:59:04 GMT

It's a good question.

There are some types that are not derived from NSObject, these types are called "Primitive Types." Some examples of these types are

int
bool
short
long
double
char

Sooooo basically any type that is not derived from the NSObject class is a Primitive type and does not require a "*".

Now I bet you are wondering how do I figure out if it's a primitive type or not.

An easy way is to look at the color of the syntax in xCode, is it deep blue or a sky blue? Deep blue = primitive type, but this is not entirely reliable as the standards for coloring syntax can fluctuate or change.

You can option-click on the object after you have typed it in xCode, click the little book in the upper right hand corner, when the class reference viewer comes up, look and see if it inherits from NSObject. If it doesn't it's Primitive and you don't need a "*".

Note:

int

NSInteger,

Just for fun:

value types

int i = 5;

System.Int32 i = new System.Int32(5);

Cocoa Programming For Mac OS X -- Objective C

Ben Coffman — Wed, 14 Apr 2010 03:10:59 GMT

I'll keep this post short. I read this book to prepare myself for iPhone development and give me a deeper understanding of Objective C. This book is probably the best book to start learning Cocoa Programming currently on the market. It gives chapter by chapter examples with exercises to follow along with. The only shortcoming of the book is that it's a bit dated to what the current xCode version is. A few of the examples might take the novice for a spin (which means it took me for a spin, sometimes a quite frustrating spin) because the step by step instructions are not exactly correct due to the fact some of the menu items have changed or been rearranged. Outside of a few minor issues, like the one I mentioned earlier, it's a pretty fun book and I would recommend it to other experienced programmers. Hopefully Mr. Hillegass will come out with a newer version.

Things covered in the book

Memory Management

Target/Actions

Helper Objects

Key-Value Coding; Key-Value Observing

NSArrayController

NSUndoManager

Archiving

Basic Core Data

Nib Files and NSWindowController

User Defaults

Using Notifications

Using Alert Panels

Localization

The list keeps going, it really covers all you need to know for having a strong hold on the basics.

Comparing Values with Objective C, Alpha Or Numeric

Ben Coffman — Sat, 02 Jan 2010 01:51:02 GMT

The Problem:
Not being able to do a simple compare in an "if statement" between two alpha or numerical statements while programing in objective C.

The Solution:
NSOrderedSame

Example Of Use:
This compares the value of "key" to the value of "support." If they are equal then you get a return value of true.

if ([key compare:Support] == NSOrderedSame)

Explanation:
For some reason Objective-C decided to make it a little bit harder to compare values. Instead of just using the traditional way "[key compare:Support]" return a true value for the if statement OR "([key compare:Support] == 0) OR "([key compare:Support] == true)" they decided to make it a little bit more complex. As demonstrated above. I'm sure the writers of Objective-C have a good reason for this, but one more level of abstraction could make Objective-C that much friendlier to it's programmers and isn't that what it's all about in the end...getting more people to develop in your language.

Some of other comparisons you might want to use are:
NSOrderedAscending -- The left operand is smaller than the right operand.
<" in most languages.
This is equivalent to using "
NSOrderedDescending -- The left operand is greater than the right operand.
This is equivalent to using ">" in most languages.

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.

unable to read unknown load command 0x80000022

Ben Coffman — Fri, 18 Sep 2009 02:01:43 GMT

Error Readout:
unable to read unknown load command 0x80000022

Fix:
Upgrade to xCode 3.2 with the 10.6 libraries.

Explanation:
This error doesn't do anything to your application except provide some really annoying output to your Debugger Console. File under annoying. You can get xCode 3.2 DOWNLOAD HERE for free at the apple website. It will require you to create a login.

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.