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  • Regarding xml parsing in iphone

    - by Prash.......
    hi... I am developing an applictaion in which i am doing xml parsing i found an error in [xmlparse parse] method. and the error for this is as follows: [NSCFString bytes]: unrecognized selector sent to instance 0x3df6310 2010-04-30 00:09:46.302 SPCiphone2[4234:1003] void SendDelegateMessage(NSInvocation*): delegate () failed to return after waiting 10 seconds. main run loop mode: kCFRunLoopDefaultMode code snippet for this as follows. responseOfWebResultData = [[NSMutableString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; NSLog(@"result: %@", responseOfWebResultData); //starting the XML parsing if(responseOfWebResultData) { @try { xmlParser = [[NSXMLParser alloc] initWithData:responseOfWebResultData]; [xmlParser setDelegate: self]; [xmlParser setShouldResolveExternalEntities: YES]; [xmlParser parse]; [responseOfWebResultData release]; } @catch(NSException *e) { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Please " message:[e reason] delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil]; [alert show]; [alert release]; } }

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  • Recommended textbook for machine-level programming?

    - by Norman Ramsey
    I'm looking at textbooks for an undergraduate course in machine-level programming. If the perfect book existed, this is what it would look like: Uses examples written in C or assembly language, or both. Covers machine-level operations such as two's-complement integer arithmetic, bitwise operations, and floating-point arithmetic. Explains how caches work and how they affect performance. Explains machine instructions or assembly instructions. Bonus if the example assembly language includes x86; triple bonus if it includes x86-64 (aka AMD64). Explains how C values and data structures are represented using hardware registers and memory. Explains how C control structures are translated into assembly language using conditional and unconditional branch instructions. Explains something about procedure calling conventions and how procedure calls are implemented at the machine level. Books I might be interested in would probably have the words "machine organization" or "computer architecture" in the title. Here are some books I'm considering but am not quite happy with: Computer Systems: A Programmer's Perspective by Randy Bryant and Dave O'Hallaron. This is quite a nice book, but it's a book for a broad, shallow course in systems programming, and it contains a great deal of material my students don't need. Also, it is just out in a second edition, which will make it expensive. Computer Organization and Design: The Hardware/Software Interface by Dave Patterson and John Hennessy. This is also a very nice book, but it contains way more information about how the hardware works than my students need. Also, the exercises look boring. Finally, it has a show-stopping bug: it is based very heavily on MIPS hardware and the use of a MIPS simulator. My students need to learn how to use DDD, and I can't see getting this to work on a simulator. Not to mention that I can't see them cross-compiling their code for the simulator, and so on and so forth. Another flaw is that the book mentions the x86 architecture only to sneer at it. I am entirely sympathetic to this point of view, but news flash! You guys lost! Write Great Code Vol I: Understanding the Machine by Randall Hyde. I haven't evaluated this book as thoroughly as the other two. It has a lot of what I need, but the translation from high-level language to assembler is deferred to Volume Two, which has mixed reviews. My students will be annoyed if I make them buy a two-volume series, even if the price of those two volumes is smaller than the price of other books. I would really welcome other suggestions of books that would help students in a class where they are to learn how C-language data structures and code are translated to machine-level data structures and code and where they learn how to think about performance, with an emphasis on the cache.

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  • Comparison of algorithmic approaches to the N queens problem

    - by iceman
    I wanted to evaluate performance comparisons for various approaches to solving the N queens problem. Mainly AI metaheuristics based algorithms like simulated annealing, tabu search and genetic algorithm etc compared to exact methods(like backtracking). Is there any code available for study? A lot of real-world optimization problems like it consider cooperative schemes between exact methods and metaheuristics.

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  • Please help with iPhone Memory & Images, memory usage crashing app

    - by Andrew Gray
    I have an issue with memory usage relating to images and I've searched the docs and watched the videos from cs193p and the iphone dev site on memory mgmt and performance. I've searched online and posted on forums, but I still can't figure it out. The app uses core data and simply lets the user associate text with a picture and stores the list of items in a table view that lets you add and delete items. Clicking on a row shows the image and related text. that's it. Everything runs fine on the simulator and on the device as well. I ran the analyzer and it looked good, so i then starting looking at performance. I ran leaks and everything looked good. My issue is when running Object Allocations as every time i select a row and the view with the image is shown, the live bytes jumps up a few MB and never goes down and my app eventually crashes due to memory usage. Sorting the live bytes column, i see 2 2.72MB mallocs (5.45Mb total), 14 CFDatas (3.58MB total), 1 2.74MB malloc and everything else is real small. the problem is all the related info in instruments is really technical and all the problem solving examples i've seen are just missing a release and nothing complicated. Instruments shows Core Data as the responsible library for all but one (libsqlite3.dylib the other) with [NSSQLCore _prepareResultsFromResultSet:usingFetchPlan:withMatchingRows:] as the caller for all but one (fetchResultSetReallocCurrentRow the other) and im just not sure how to track down what the problem is. i've looked at the stack traces and opened the last instance of my code and found 2 culprits (below). I havent been able to get any responses at all on this, so if anyone has any tips or pointers, I'd really appreciate it!!!! //this is from view controller that shows the title and image - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; self.title = item.title; self.itemTitleTextField.text = item.title; if ([item.notes length] == 0) { self.itemNotesTextView.hidden = YES; } else { self.itemNotesTextView.text = item.notes; } //this is the line instruments points to UIImage *image = item.photo.image; itemPhoto.image = image; } - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { // Delete the managed object for the given index path NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; [context deleteObject:[fetchedResultsController objectAtIndexPath:indexPath]]; // Save the context. NSError *error = nil; if (![context save:&error]) //this is the line instruments points to { NSLog(@"Unresolved error %@, %@", error, [error userInfo]); exit(-1); } } }

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  • Postgres: Convert varchar to text

    - by williamjones
    I screwed up and created a column as a varchar(255) where that is no longer sufficient. I've read that varchar has no performance benefits over text on Postgres, and so would like to convert the varchar to a text column in a safe way that preserves the data. What's the best way for me to do this?

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  • Memory leak appears only when multiprocessing

    - by Sandro
    I am trying to use python's multiprocessing library to hopefully gain some performance. Specifically I am using its map function. Now, for some reason when I swap it out with its single threaded counterpart I don't get any memory leaks over time. But using the multiprocessing version of map causes my memory to go through the roof. For the record I am doing something which can easily hog up loads of memory, but what would the difference be between the two to cause such a stark difference?

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  • Can we change dynamically the interval of "schedule" ?

    - by micropsari
    Hello, I'm making a game on iPhone using cocos2d, and I have a question. In my init method I'm doing this : [self schedule:@selector(newMonster:) interval:1]; It create a new monster every second. But I'd like that the interval change over time. For example : -The 10 first seconds of the game: a new monster appears every 1 second. -Then for 10 seconds: a new monster appears every 0.8 second. -And after every 0.5 second... How can I do that? Thanks !

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  • What is the need of collection framework in java?

    - by JavaUser
    Hi, What is the need of Collection framework in Java since all the data operations(sorting/adding/deleting) are possible with Arrays and moreover array is suitable for memory consumption and performance is also better compared with Collections. Can anyone point me a real time data oriented example which shows the difference in both(array/Collections) of these implementations. Thx

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  • Can I create a UITableViewController that inherits from a custom subclass of UIViewController?

    - by prendio2
    I have common functionality that I need to access from all screens of my app: a right bar button item and associated action. So as not to repeat the code I would like to set this up in a custom UIViewController and have all my view controllers inherit from it. - (void)viewDidLoad { UIBarButtonItem *rightBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemPlay target:self action:@selector(lightsCamera)]; self.navigationItem.rightBarButtonItem = rightBarButton; } - (void)lightsCamera { … } However, I have a number of UITableViewControllers however and I would like to know if it is possible for them to inherit the functionality too?

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  • Cocoa multiple threads, locks don't work

    - by Igor
    I have a threadMethod which shows in console robotMotorsStatus every 0.5 sec. But when I try to change robotMotorsStatus in changeRobotStatus method I receive an exception. Where I need to put locks in that program. #import "AppController.h" @implementation AppController extern char *robotMotorsStatus; - (IBAction)runThread:(id)sender { [self performSelectorInBackground:@selector(threadMethod) withObject:nil]; } - (void)threadMethod { char string_to_send[]="QFF001100\r"; //String prepared to the port sending (first inintialization) string_to_send[7] = robotMotorsStatus[0]; string_to_send[8] = robotMotorsStatus[1]; while(1){ [theLock lock]; usleep(500000); NSLog (@"Robot status %s", robotMotorsStatus); [theLock unlock]; } } - (IBAction)changeRobotStatus:(id)sender { robotMotorsStatus[0]='1'; }

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  • Reasons for Parallel Extensions working slowly

    - by darja
    I am trying to make my calculating application faster by using Parallel Extensions. I am new in it, so I have just replaced the main foreach loop with Parallel.ForEach. But calculating became more slow. What can be common reasons for decreasing performance of parallel extensions? Thanks

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  • Using memcached as a session storage with CodeIgniter

    - by Alex N.
    I am researching possibilities of using memcached as a session storage for a system built on CodeIgniter. Has anybody done this before(that's probably a stupid question :) and if so what's your experience folks? Have you used any existing libraries/extensions? As far as performance improvement what have you seen? Any caveats?

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  • How to select nth element of particular type in enlive?

    - by Mad Wombat
    I am trying to scrape some data from a page with a table based layout. So, to get some of the data I need to get something like 3rd table inside 2nd table inside 5th table inside 1st table inside body. I am trying to use enlive, but cannot figure out how to use nth-of-type and other selector steps. To make matters worse, the page in question has a single top level table inside the body, but (select data [:body : :table]) returns 6 results for some reason. What the hell am I doing wrong?

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  • C# XPath id() not working?

    - by Iggyhopper
    I'm using C# and I'm stumped. Does it just not support id()? I have a large XML file, about 4-5 of them at ~400kb, so I need some speed and performance wherever I can get it. I use XmlDocument.SelectSingleNode("id('blahblahblah')") and it doesn't get the node by id. Am I going crazy or is it that C# XPath just doesn't support id()?

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  • Exploding by Array of Delimiters

    - by JoeC
    Is there any way to explode() using an array of delimiters? PHP Manual: array explode ( string $delimiter , string $string [, int $limit ] ) Instead of using string $delimiter is there any way to use array $delimiter without affecting performance too much?

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