objective-c

How are files (especially audio files) organized internally?

I try to grok that: Apple is talking about "packets" in audio files, and there is a fancy function called AudioFileReadPackets which takes a lot of arguments. One of them specifies the "start packet", and another one the number of packets which you want to read. So I imagine an audio file to look like this, internally: It's made up of a...

Is developing iPhone apps in any language other than Objective-C ever a truly viable solution?

I hear all this stuff about crazy ways to build iPhone apps using Ruby or C# under .NET or the like. Even stuff about developing apps on Windows using Java, or auto-generated apps using Flash CS5 or something. Now, I've never really spent any time at all investigating these claims—I just brushed them off as clumsy or cumbersome or downr...

Should i use a C function or Obj-C Method?

I'm about to create a function which adds two NSDateComponents together is there any advantage to putting this in a C style function or should it go in a Obj-C method? Is there ever a reason to use one rather then the other or should I always stick to Obj-C? BTW: Not that it makes any difference I'm sure but this is for an app on the i...

Which pdf elements could cause crashes?

This is a very general question but it's based on a specific problem. I've created a pdf reader app for the iPad and it works fine except for certain pdf pages which always crash the app. We now found out that the very same pages cause Safari to crash as well, so as I had started to suspect the problem is somewhere in Apple's pdf renderi...

Typecasting doesn't work. How to convert an object?

Hi everyone! I need to convert a custom object to a different object. How can I do that? I know that typecasting doesn't work (the only thing is does is "shuts the compiler warnings off", but nothing more). Here is a sample code: MyType* obj1; MyOtherType* obj2; obj1 = [MyType initWithData: 1]; obj2 = (MyOtherType*) obj1; if ([obj2 ...

name of UIView that was touched

Hi, How can I get the name of the [touch view] in the touchesbegan event. So if it were UIView *aaaaaview I would get aaaaaview as the return; Thank You, nonono ...

Handling the rel attribute in a UIWebView?

Is there a way for my UIWebViewDelegate to see what the rel attribute of a clicked < a> element is? ...

Implementing NSToolbar

Im trying to Implement my application with NSToolbar. I know I need to add the following, but I don't know where... IBOutlet NSWindow *window; ...

obj-c : iphone programming disabling the round off of a number

hi, i need to show a number to a user : 1.96666777 (timeHour) moduloformat = [NSString stringWithFormat:@"%0.0f hours ",timeHour]; but it is rounding off the number automaticly. It gives "2" and i want to show "1" i could use a NSrange and take the first number but i wanna know how to deal with this. Thanks!! ...

How do I pass (by value) a struct in Objective-C?

This one has been driving me mad! I have a struct: typedef struct{ int a; }myStruct; Then I have: myStruct tempStruct; I am trying to pass the struct to a class method whose implementation is: - (void) myFunc:(struct myStruct)oneOfMyStructs{}; I call the method like so: [myClass myFunc:(struct myStruct)tempStruct]; The com...

How, exactly, does the double-stringize trick work?

At least some C preprocessors let you stringize the value of a macro, rather than its name, by passing it through one function-like macro to another that stringizes it: #define STR1(x) #x #define STR2(x) STR1(x) #define THE_ANSWER 42 #define THE_ANSWER_STR STR2(THE_ANSWER) /* "42" */ Example use cases here. This does work, at least i...

Can't get Jacobi algorithm to work in Objective-C

Hi, For some reason, I can't get this program to work. I've had other CS majors look at it and they can't figure it out either. This program performs the Jacobi algorithm (you can see step-by-step instructions and a MATLAB implementation here). BTW, it's different from the Wikipedia article of the same name. Since NSArray is one-dimen...

How to directly store SQLite data in XCode?

Hi guys: Searched on here and got some vague answers, so I thought i'd rephrase the problem to get some clearer answers- Right now I have an SQL Lite db that reads/parses information from a pre-formatted .txt file. When I open the app, there is a slight 'lag' as the iDevice parses the info, then gets fetched for the iDevice. I'm just wo...

Fully-loaded UIViewController losing all it's data after adding to scroll view

Summary I'm repurposing Apple's Page Control project. In loadScrollViewWithPage:, the view controllers that I'm adding to the scroll view appear on screen without their initialized values, as if displayed directly from the nib. Specifics Here's the code that appears to be working when I step through it: CBFullScreenViewController *c...

Multiple View application and Navigation Bar

Hi. I'm working in a iphone view-based application. The application works this way: First view is a welcome view with buttons for load other views. Second view is a map that shows the location using gps. Third view is a search engine that loads some information to show on the map and on a list (This has two button to load map or table). ...

Debugging runtime error "Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:'"

I'm going through the Beginning iPhone Development book & stuck in chapter 9. I've spent a few hours trying to debug this error w/o avail: 2010-05-01 19:27:51.361 Nav2[4113:20b] *** Assertion failure in -[UITableView _createPreparedCellForGlobalRow:withIndexPath:], /SourceCache/UIKit/UIKit-984.38/UITableView.m:4709 2010-05-01 19:27:51....

Get name given by phone number on the iPhone

I'm using a TextField where the user types a phone number. When the TextField changes, it should check if this number is already in the phonebook and display the name. So far, my only way is to parse all names and number in a Dict and read it from there. Is there a simpler, more efficient and sophisticated way to do that? ...

Why is my UITableView not being set?

I checked using the debbuger in the viewDidLoad method and tracerTableView is 0x0 which i assume means it is nil. I don't understand. I should go ahaed say yes I have already checked my nib file and yes all the connections are correct. Here is the header file and the begging of the .m. ///////////// .h file //////////// @interface T...

What's the best way to have functions share an array in Objective-C?

I understand that in Objective-C you declare an array in the header file and interact with it in a class. So far I'm adding things and fetching them fine within a single function. I'm new to the language however and can't figure out how to share that array across other functions. I'd like to initialize array data in my viewDidLoad and a...

Does it ever make sense to call [init] outside of [[alloc] init]?

I am wondering if [[alloc] init] is just a convention or if separating the two calls has wider use. For instance, I wonder if people ever call [init] (or friends) on an existing object to "re-initialize" it. ...