How do those bitmasks actually work?

Posted by mystify on Stack Overflow See other posts from Stack Overflow or by mystify
Published on 2010-03-31T17:31:57Z Indexed on 2010/03/31 17:53 UTC
Read the original article Hit count: 469

Filed under:

iphone

|

objective-c

|

cocoa

|

cocoa-touch

For example, this method from NSCalendar takes a bitmask:

- (NSDate *)dateByAddingComponents:(NSDateComponents *)comps toDate:(NSDate *)date options:(NSUInteger)opts

So options can be like:

NSUInteger options = kCFCalendarUnitYear;

or like:

NSUInteger options = kCFCalendarUnitYear | kCFCalendarUnitMonth | kCFCalendarUnitDay;

What I don't get is, how is this actually done? I mean: How can they pull out those values which are merged into options? If I wanted to program something like this, that can take a bitmask, how would that look?

© Stack Overflow or respective owner

Related posts about iphone

iphone - direct link to iPhone review form from inside iphone

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to link directly to the review link of one of my Apps. I know that it is possible because Appirater did it in the past, but some change in iTunes turned the API down. Appirater uses this URL NSString *templateReviewURL = @"itms-apps://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews… >>> More
Buy iPhone 4 Without Contract: $599 (AT&T) and $699 (Verizon)

as seen on Tech Dreams - Search for 'Tech Dreams'
Purchasing iPhone without a contract is a good option when you are planning to gift it to someone or going to use it outside US. Both AT&T and Verizon lets you iPhone 4 without a contract but this information is buried deep under blurred text in FAQs and agreements. Here is the pricing… >>> More
Is it possible to download and run IPhone apps on an IPhone emulator

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am tasked to provide an IPhone client app for our SaaS website. I have never written an IPhone application, nor do I have an IPhone at the moment. Before I can decide whether or not I want to do this myself or outsource this, I'd like to try a few apps myself to get a feeling for the UI. Is… >>> More
iPhone web app from dashcode rss feed template works deployed on simulator but not on iphone

as seen on Stack Overflow - Search for 'Stack Overflow'
iPhone web app from dashcode rss feed template works deployed on simulator but not on iphone. The web app is deployed at; http://www.alila.se/wordpress/index.html If i run the simulator and enter that adress, it fetches the rss feed and displays it. Everything fine. When i enter the adress into… >>> More
Problem running iPhone application on iPhone from Xcode (and in Instruments)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi I have a problem running one application on the iPhone from Xcode (or Instruments). When I try to run the app I get the error message Failed to upload XXX.app in the bottom left corner of Xcode. The strange thing is it actually uploaded the app to the iPhone but it doesn't start it (after this… >>> More

Related posts about objective-c

Blocking access to websites with objective-C / root privileges in objective-C

as seen on Stack Overflow - Search for 'Stack Overflow'
I am writing a program in Objective-C (XCode 3.2, on Snow Leopard) that is capable of either selectively blocking certain sites for a duration or only allow certain sites (and thus block all others) for a duration. The reasoning behind this program is rather simple. I tend to get distracted when I… >>> More
Objective-C with some Objective-C++, calling a normal c++ method "referenced from" problem

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I made an Objective-C project for the iPhone. I had only one cpp class, the soundEngine taken from some Apple demo. Now I'm trying to merge OpenFeint which is coded in Objective-C++. As soon as I drop in the code without even referring to it from my code, when I hit Build, my Objective-C code… >>> More
Add an objective @property attribute in objective-c

as seen on Stack Overflow - Search for 'Stack Overflow'
Does anyone know of a way to add additional attribute types to the @property keyword without modifying the compiler? Or can anyone think of another way to genericize getter/setter creation? Basically, I have a lot of cases in a recent project where it's handy for objects to lazily instantiate their… >>> More
ObjectiveC Syntax for Specifying Protocol Name in Method Argument

as seen on Stack Overflow - Search for 'Stack Overflow'
What's the ObjectiveC syntax for specifying a protocol as an argument in a method? Say I have 2 protocols, MyProtocol and MyProtocolCB: @protocol MyProtocolCB <NSObject> - (void) func; @end @protocol MyProtocol <NSObject> - (void) register:(MyProtocolCB*) cb; @end I'm receiving this… >>> More
ObjectiveC builtin template system ?

as seen on Stack Overflow - Search for 'Stack Overflow'
I am developing an iPhone application and I use HTML to display formatted text. I often display the same webpage, but with a different content. I would like to use a template HTML file, and then fill it with my diffent values. I wonder if ObjectiveC has a template system similar to ERB in Ruby. That… >>> More