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  • Learn Obj-C Memory Management

    - by Joshua Brickner
    I come from a web development background. I'm good at XHTML, CSS, JavaScript, PHP and MySQL, because I use all of those technologies at my day job. Recently I've been tinkering with Obj-C in Xcode in the evenings and on weekends. I've written code for both the iPhone and Mac OS X, but I can't wrap my head around the practicalities of memory management. I understand the high-level concepts but am unclear how that plays out in implementation. Web developers typically don't have to worry about these sorts of things, so it is pretty new to me. I've tried adding memory management to my projects, but things usually end up crashing. Any suggestions of how to learn? Any suggestions are appreciated.

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  • Detecting Acceleration in a car (iPhone Accelerometer)

    - by TheGazzardian
    Hello, I am working on an iPhone app where we are trying to calculate the acceleration of a moving car. Similar apps have accomplished this (Dynolicious), but the difference is that this app is designed to be used during general city driving, not on a drag strip. This leads us to one big concern that Dynolicious was luckily able to avoid: hills. Yes, hills. There are two important stages to this: calibration, and actual driving. Our initial run was simple and suffered the consequences. During the calibration stage, I took the average force on the phone, and during running, I just subtracted the average force from the current force to get the current acceleration this frame. The problem with this is that the typical car receives much more force than just the forward force - everything from turning to potholes was causing the values to go out of sync with what was really happening. The next run was to add the condition that the iPhone must be oriented in such a way that the screen was facing toward the back of the car. Using this method, I attempted to follow only force on the z-axis, but this obviously lead to problems unless the iPhone was oriented directly upright, because of gravity. Some trigonometry later, and I had managed to work gravity out of the equation, so that the car was actually being read very, very well by the iPhone. Until I hit a slope. As soon as the angle of the car changed, suddenly I was receiving accelerations and decelerations that didn't make sense, and we were once again going out of sync. Talking with someone a lot smarter than me at math lead to a solution that I have been trying to implement for longer than I would like to admit. It's steps are as follows: 1) During calibration, measure gravity as a vector instead of a size. Store that vector. 2) When the car initially moves forward, take the vector of motion and subtract gravity. Use this as the forward momentum. (Ignore, for now, the user cases where this will be difficult and let's concentrate on the math :) 3) From the forward vector and the gravity vector, construct a plane. 4) Whenever a force is received, project it onto said plane to get rid of sideways force/etc. 5) Then, use that force, the known magnitude of gravity, and the known direction of forward motion to essentially solve a triangle to get the forward vector. The problem that is causing the most difficulty in this new system is not step 5, which I have gotten to the point where all the numbers look as they should. The difficult part is actually the detection of the forward vector. I am selecting vectors whose magnitude exceeds gravity, and from there, averaging them and subtracting gravity. (I am doing some error checking to make sure that I am not using a force just because the iPhone accelerometer was off by a bit, which happens more frequently than I would like). But if I plot these vectors that I am using, they actually vary by an angle of about 20-30 degrees, which can lead to some strong inaccuracies. The end result is that the app is even more inaccurate now than before. So basically - all you math and iPhone brains out there - any glaring errors? Any potentially better solutions? Any experience that could be useful at all? Award: offering a bounty of $250 to the first answer that leads to a solution.

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  • How can I pass a UIEvent to a UIScrollView

    - by rickharrison
    I am subclassing UIWindow and creating an implementation of sendEvent: as follows: - (void)sendEvent:(UIEvent *)event { [super sendEvent:event]; // Send event to UIScrollView here } How can I send the event to a UIScrollView. I tried calling the touchesBegan:, etc. messages, but that did not do anything.

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  • Why do my raytraced spheres have dark lines when lit with multiple light sources?

    - by Curyous
    I have a simple raytracer that only works back up to the first intersection. The scene looks OK with two different light sources, but when both lights are in the scene, there are dark shadows where the lit area from one ends, even if in the middle of a lit area from the other light source (particularly noticeable on the green ball). The transition from the 'area lit by both light sources' to the 'area lit by just one light source' seems to be slightly darker than the 'area lit by just one light source'. The code where I'm adding the lighting effects is: // trace lights for ( int l=0; l<primitives.count; l++) { Primitive* p = [primitives objectAtIndex:l]; if (p.light) { Sphere * lightSource = (Sphere *)p; // calculate diffuse shading Vector3 *light = [[Vector3 alloc] init]; light.x = lightSource.centre.x - intersectionPoint.x; light.y = lightSource.centre.y - intersectionPoint.y; light.z = lightSource.centre.z - intersectionPoint.z; [light normalize]; Vector3 * normal = [[primitiveThatWasHit getNormalAt:intersectionPoint] retain]; if (primitiveThatWasHit.material.diffuse > 0) { float illumination = DOT(normal, light); if (illumination > 0) { float diff = illumination * primitiveThatWasHit.material.diffuse; // add diffuse component to ray color colour.red += diff * primitiveThatWasHit.material.colour.red * lightSource.material.colour.red; colour.blue += diff * primitiveThatWasHit.material.colour.blue * lightSource.material.colour.blue; colour.green += diff * primitiveThatWasHit.material.colour.green * lightSource.material.colour.green; } } [normal release]; [light release]; } } How can I make it look right?

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  • Integrating a C project in the iPhone SDK

    - by iPhoneARguy
    Hello, This is my first time doing this sort of project so apologies if the question is silly. I've got a question about using a C project with a project in the iPhone SDK. I've dragged and dropped the C project into the iPhone project in Xcode (so it appears in the screenshot below). sjeng.h is a file inside GameEngine.xcodeproj, but when I try to include the header file, I not only receive an error, but the file it is looking for seems to be capitalized whereas the import statement is not. (I would post a screenshot but this is my first time doing something on stack overflow and I need more reputation points. The URL of the screenshot is here: http://imgur.com/AdrGL.png) Does anyone know what the problem might be? Thanks!

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  • Display subclass data in XCode Expression window

    - by Nick VanderPyle
    I'm debugging an iPhone application I've written using XCode 3.2 and I cannot view the relevant public properties of an object I pull from Core Data. When I watch the object in the Expressions window it only displays the data from the base NSManagedObject. I'd like to see the properties that are on the subclass, not the superclass. If it helps, here's some of the code I'm using. Settings is a subclass of NSManagedObject. I created it using XCode's built-in modeler. Declared like: @interface Settings : NSManagedObject { } @property (nonatomic, retain) NSNumber * hasNews; @property (nonatomic, retain) NSString * logoUrl; @property (nonatomic, retain) NSNumber * hasPaymentGateway; @property (nonatomic, retain) NSString * customerCode; ... In the interface of my controller I have: Settings *settings; I populate settings with: settings = (Settings *)[NSEntityDescription insertNewObjectForEntityForName:@"Settings" inManagedObjectContext:UIAppManagedObjectContext()]; I then set the properties like: settings.hasNews = [NSNumber numberWithBool:TRUE]; I've tried casting settings as (Settings *) in the Expression window but that doesn't help. All I see are the properties to NSManagedObject. I'm using NSLog but would rather not.

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  • why retain of delegate is wrong what are all alternatives...?

    - by jeeva
    Hi, I have one problem let assume A and B are 2 view controller from A user push to B view controller,In B user starts some download by creating object C(which is NSObject class) and sets B as delegate to C(assign),now user want go back to A then dealloc of B calls object releases, C delegate fails to give call back(crashes).I want to get call and allow user to move to other view controller thats way i am retain the delegate in C class but retain of delegate is wrong ... what are all solutions ... Thanks in Advance.

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  • UIView Login screen to tabbar logic

    - by Benjamin De Bos
    Folks, i'm having trouble with some navigation logic. Currently i have a simple two tabbed tabbar application. But i want to show a loginscreen in front. So that would be an UIView. Currently the code is as follows: - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; UIViewController *viewController1 = [[roosterViewController alloc] initWithNibName:@"roosterViewController" bundle:nil]; UIViewController *viewController2 = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil]; self.tabBarController = [[UITabBarController alloc] init]; self.tabBarController.viewControllers = @[viewController1, viewController2]; self.window.rootViewController = self.tabBarController; [self.window makeKeyAndVisible]; return YES; } SO this pushes a simple tabcontroller. Well, now i want to have a login screen. So that would be a simple UIView which pushes the tabbar controller. But i can't seem to see the logic on how to do this. I've been trying to present a modal view controller, but the thing is: the tabbar will be loaded on the background. Since i need the username/password information to work on the tabbarview, this won't work. My Logic would be: delegate load loginViewController load tabbar controller But, then i need to be able to "logout". So i need to destroy the tabbar controller and present the login screen. Any thoughts on this?

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  • Getting RSSIValue from IOBluetoothHostController

    - by Tanner Ezell
    I'm trying to write a simple application that gathers the RSSIValue and displays it via NSLog, my code is as follows: #import <Foundation/Foundation.h> #import <Cocoa/Cocoa.h> #import <IOBluetooth/objc/IOBluetoothDeviceInquiry.h> #import <IOBluetooth/objc/IOBluetoothDevice.h> #import <IOBluetooth/objc/IOBluetoothHostController.h> #import <IOBluetooth/IOBluetoothUtilities.h> @interface getRSSI: NSObject {} -(void) readRSSIForDeviceComplete:(id)controller device:(IOBluetoothDevice*)device info:(BluetoothHCIRSSIInfo*)info error:(IOReturn)error; @end @implementation getRSSI - (void) readRSSIForDeviceComplete:(id)controller device:(IOBluetoothDevice*)device info:(BluetoothHCIRSSIInfo*)info error:(IOReturn)error { if (error != kIOReturnSuccess) { NSLog(@"readRSSIForDeviceComplete return error"); CFRunLoopStop(CFRunLoopGetCurrent()); } if (info->handle == kBluetoothConnectionHandleNone) { NSLog(@"readRSSIForDeviceComplete no handle"); CFRunLoopStop(CFRunLoopGetCurrent()); } NSLog(@"RSSI = %i dBm ", info->RSSIValue); [NSThread sleepUntilDate: [NSDate dateWithTimeIntervalSinceNow: 5]]; [device closeConnection]; [device openConnection]; [controller readRSSIForDevice:device]; } @end int main (int argc, const char * argv[]) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSLog(@"start"); IOBluetoothHostController *hci = [IOBluetoothHostController defaultController]; NSString *addrStr = @"xx:xx:xx:xx:xx:xx"; BluetoothDeviceAddress addr; IOBluetoothNSStringToDeviceAddress(addrStr, &addr); IOBluetoothDevice *device = [[IOBluetoothDevice alloc] init]; device = [IOBluetoothDevice withAddress:&addr]; [device retain]; [device openConnection]; getRSSI *rssi = [[getRSSI alloc] init]; [hci setDelegate:rssi]; [hci readRSSIForDevice:device]; CFRunLoopRun(); [hci release]; [rssi release]; [pool release]; return 0; } The problem I am facing is that the readRSSIForDeviceComplete seems to work just fine, info passes along a value. The problem is that the RSSI value is drastically different from the one I can view from OS X via option clicking the bluetooth icon at the top. It is typical for my application to print off 1,2,-1,-8,etc while the menu displays -64 dBm, -66, -70, -42, etc. I would really appreciate some guidance.

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  • iPhone application update (using Core Data on Sqlite)

    - by owen
    I have an app which is using Core Data on Sqlite, Now I have a update which has some DB structure changes say adding a new table I know when an app get updated, it updates the app binary only, nothing on document directory will be changed. When the app gets updated and launchs at the first time and run [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; It will find the difference between the data model and DB structure in Sqlite and will throw an exception and quit. Error: "The model used to open the store is incompatible with the one used to create the store" So, can anyone here give me some idea how to update an app when there is a DB structure change? I think we can run a DB script to create that new table when it launchs the update at the first time. But if there are other changes like changing the type of some fields or deleting some fields, and we need to migrate the old data, this is really a headache. In this case, Is the only way to do is creating a new app? Is there anyone tried something similar like this?

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  • Getting "Location" header from NSHTTPURLResponse

    - by aspcartman
    Can't get "Location" header from response at all. Wireshark says that i've got one: Location: http://*/index.html#0;sid=865a84f0212a3a35d8e9d5f68398e535 But NSHTTPURLResponse *hr = (NSHTTPURLResponse*)response; NSDictionary *dict = [hr allHeaderFields]; NSLog(@"HEADERS : %@",[dict description]); Produces this: HEADERS : { Connection = "keep-alive"; "Content-Encoding" = gzip; "Content-Type" = "text/html"; Date = "Thu, 25 Mar 2010 08:12:08 GMT"; "Last-Modified" = "Sat, 29 Nov 2008 15:50:54 GMT"; Server = "nginx/0.7.59"; "Transfer-Encoding" = Identity; } No location anywhere. How to get it? I need this "sid" thing.

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  • Adding ivars to NSManagedObject subclass

    - by The Crazy Chimp
    When I create an entity using core data then generate a subclass of NSManagedObject from it I get the following output (in the .h): @class Foo; @interface Foo : NSManagedObject @property (nonatomic, retain) NSString *name; @property (nonatomic, retain) NSSet *otherValues; @end However, in my .m file I want to make use of the name and otherValues values. Normally I would simply create a couple of ivars and then add the properties for them as I required. That way I can access them in my .m file easily. In this situation would it be acceptable to do this? Would adding ivars to the .h (for name and otherValues) cause any unusual behaviour in the persistance & retrieval of objects?

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  • AVAudioPlayer problem regarding song overlaping in iPhone

    - by riteshkumar1905
    I have using AVAudioPlayer in my app but the problem is that when i play the song from list it will played while before stopping the song i am again goes to song list then select another song then both song will start playing simultaneously so please tell me the code which will terminate my first song. i am using avTouchContoller & avTouchViewController in my app. so i am enclosing the code for song which is written in avController.m & avTouchViewController.m as follow for single song avtouchController.m switch (flag) { case 1: //[self stop]; fileURL = [[NSURL alloc] initFileURLWithPath: [[NSBundle mainBundle] pathForResource:@"Aarti Keeje" ofType:@"aac"]]; self._player = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:nil]; //self._player=newplayer; //[newplayer release]; if (self._player) { _fileName.text = [NSString stringWithFormat: @"%@ (%d ch.)", [[self._player.url relativePath] lastPathComponent], self._player.numberOfChannels, nil]; [self updateViewForPlayerInfo]; [self updateViewForPlayerState]; } [fileURL release]; break;

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  • Animating an Image

    - by Viral
    hi friends, I m creating a game, in that i want to use some animation, but i m new to animations. I want to create an image ,as soon as i click on imageview, the image should come in bouncing manner as if it is a Ball, so is it possible to do so??? The image is predefined for the game.and it must come after touch begin event occures, can any one help me??? regards viral.

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  • Iphone - How to load Chinese text

    - by Dave
    Hi, I have a file with Chinese text that I want to use in my xcode project (I'm planning to load it through a database as it is lot of text), the problem is I dont know how to add the font to my project so that its viewable when used on an iPhone? Thanks :)

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  • How are binding specified for Interface Builder plugins?

    - by Benedict Cohen
    I'm creating an Interface Builder plugin for an NSView subclass. I've been following the Interface Builder Plug-in Programming Guide but it's not answer all my questions. My class has one NSString property and 4 NSColor properties which I want to create bindings for at design time. I can't figure out where the bindings are specified in the plugin project. The documentation states that the Inspector Object is only for creating the Attribute Inspector. The class description file (.classdescription) lists outlets and actions but not bindings. Where do I specify the bindings for my class?

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  • objc[989] objc_exception_throw failed.

    - by thyrgle
    I was just adding some more CCSprites to a CCLayer and it just starts crashing giving me the error: objc[989] objc_exception_throw failed. Is there like a limit to the amount of CCSprites you can have on a screen or something? I added the CCSprites doing the following with the CCSprites already declared at interface: L1Circle1 = [CCSprite spriteWithFile:@"LaserCircle.png"]; [L1Circle1 setPosition:ccp(180,180)]; [self addChild:L1Circle1]; What am I doing wrong?

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  • MKAnnotationView for userLocation pin iPhone

    - by Mauricio Galindo
    I have an application that uses MKMapView and at some point in the app I need to remove all the current pins in the map using [mapView removeAnnotations:mapView.annotations] And then I want to show again the current user location mapView.showUserLocation = YES But I can only make it reappear as a regular pin, because the userLocation view class its not public so I cant return views of that type. Here is my code - (MKAnnotationView *)mapView:(MKMapView *)theMapView viewForAnnotation:(id <MKAnnotation>)annotation MKPinAnnotationView* annView = (MKPinAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:@"currentloc"]; if (!annView) { MKPinAnnotationView *annView=[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"currentloc"]; annView.pinColor = MKPinAnnotationColorRed; annView.animatesDrop=TRUE; annView.canShowCallout = YES; annView.calloutOffset = CGPointMake(-5, 5); if ([annotation isKindOfClass:[DraggableAnnotationAM class]] ) annView.draggable = YES; return annView; } else { if ([annotation isKindOfClass:[DraggableAnnotationAM class]] ) annView.draggable = YES; annView.annotation = annotation; return annView; } Also I have found through reflection that MKUserLocationView is the class that is used to display the current location, but because its not public its not safe to use and my app keeps crashing and Im sure theres a easier way. Is it possible to do what I want, or should I just never remove the user location annotation of the mapView? Thanks in advance

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  • NSFormatter problem: not getting called for the empty string

    - by Enchilada
    I have created a custom formatter for my (read-only) table column. It looks like this: - (NSString *)stringForObjectValue:(id)anObject { NSAssert([anObject isKindOfClass:[NSString class]] && anObject != nil, @"invalid object"); if ([anObject isEqualToString:@""]) return @"EMPTY"; else return [anObject stringByAppendingString:@"++"]; } Very simple. The corresponding objects are just strings, so it's an string-to-string formatter. All non-empty string objects are returned with @"++" appended to them. Empty string objects should be turned into the @"EMPTY" string. The @"++" gets appended to non-empty strings just fine. The problem is, @"EMPTY" never gets shown! My formatter is never called by Cocoa when the underlying object is the empty string. The corresponding row just keeps being empty, instead of showing my requested @"EMPTY". Any ideas?

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  • Monitor Network Traffic Mac

    - by Tom Irving
    I'm wondering how to go about monitoring network traffic on my Mac. Like the way activity monitor does it, showing the bytes / packets in and out. I know it's a bit vague, but I'm unsure of the best place to start.

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  • EXC_BAD_ACCESS when I change moviePlayer contentURL

    - by Bruno
    Hello, In few words, my application is doing that : 1) My main view (MovieListController) has some video thumbnails and when I tap on one, it displays the moviePlayer (MoviePlayerViewController) : MovieListController.h : @interface MoviePlayerViewController : UIViewController <UITableViewDelegate>{ UIView *viewForMovie; MPMoviePlayerController *player; } @property (nonatomic, retain) IBOutlet UIView *viewForMovie; @property (nonatomic, retain) MPMoviePlayerController *player; - (NSURL *)movieURL; @end MovieListController.m : MoviePlayerViewController *controllerTV = [[MoviePlayerViewController alloc] initWithNibName:@"MoviePlayerViewController" bundle:nil]; controllerTV.delegate = self; controllerTV.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController: controllerTV animated: YES]; [controllerTV release]; 2) In my moviePlayer, I initialize the video I want to play MoviePlayerViewController.m : @implementation MoviePlayerViewController @synthesize player; @synthesize viewForMovie; - (void)viewDidLoad { NSLog(@"start"); [super viewDidLoad]; self.player = [[MPMoviePlayerController alloc] init]; self.player.view.frame = self.viewForMovie.bounds; self.player.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight; [self.viewForMovie addSubview:player.view]; self.player.contentURL = [self movieURL]; } - (void)dealloc { NSLog(@"dealloc TV"); [player release]; [viewForMovie release]; [super dealloc]; } -(NSURL *)movieURL { NSBundle *bundle = [NSBundle mainBundle]; NSString *moviePath = [bundle pathForResource:@"FR_Tribord_Surf camp_100204" ofType:@"mp4"]; if (moviePath) { return [NSURL fileURLWithPath:moviePath]; } else { return nil; } } - It's working good, my movie is display My problem : When I go back to my main view : - (void) returnToMap: (MoviePlayerViewController *) controller { [self dismissModalViewControllerAnimated: YES]; } And I tap in a thumbnail to display again the moviePlayer (MoviePlayerViewController), I get a *Program received signal: “EXC_BAD_ACCESS”.* In my debugger I saw that it's stopping on the thread "main" : // // main.m // MoviePlayer // // Created by Eric Freeman on 3/27/10. // Copyright Apple Inc 2010. All rights reserved. // #import <UIKit/UIKit.h> int main(int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; int retVal = UIApplicationMain(argc, argv, nil, nil); //EXC_BAD_ACCESS [pool release]; return retVal; } If I comment self.player.contentURL = [self movieURL]; it's working, but when I let it, iI have this problem. I read that it's due to null pointer or memory problem but I don't understand why it's working the first time and not the second time. I release my object in dealloc method. Thanks for your help ! Bruno.

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