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  • Returning NSNull from actionForLayer:forKey

    - by MrHen
    If I implement the CALayer delegate method actionForLayer:forKey I can return [NSNull null] to force the CALayer to not animate any changes. Unfortunately, [NSNull null] doesn't implement the CAAction delegate and XCode kicks out the following warning: warning: class 'NSNull' does not implement the 'CAAction' protocol Here is the method code: - (id<CAAction>)actionForLayer:(CALayer *)theLayer forKey:(NSString *)theKey { //This disables the animations when moving things around //Also, don't animate the selection box. It was doing weird things if(undoGroupStarted || theLayer == self.selectionBox) { return [NSNull null]; } else { return nil; } } Am I doing something wrong? Is returning [NSNull null] bad behavior? If so, what is another way to do what I am trying to do here? If not, how do I make the compiler happy?

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  • Insert a tag with NSFileHandle

    - by zp26
    Hi, I want insert a tag in the Xml file. I have NSFileHandle object and i know the "offsetInFile" and the "seekToFileOffset:" methods but i don't know how to use. I have the Xml below and i want insert a tag between "positions" and "/positions" tag. Thanks so much. <?xml version=1.0 encoding=UTF-8 ?> <positions> //I want insert in this position my tag with the NSFileHandle. </positions>

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  • Using Core Data Concurrently and Reliably

    - by John Topley
    I'm building my first iOS app, which in theory should be pretty straightforward but I'm having difficulty making it sufficiently bulletproof for me to feel confident submitting it to the App Store. Briefly, the main screen has a table view, upon selecting a row it segues to another table view that displays information relevant for the selected row in a master-detail fashion. The underlying data is retrieved as JSON data from a web service once a day and then cached in a Core Data store. The data previous to that day is deleted to stop the SQLite database file from growing indefinitely. All data persistence operations are performed using Core Data, with an NSFetchedResultsController underpinning the detail table view. The problem I am seeing is that if you switch quickly between the master and detail screens several times whilst fresh data is being retrieved, parsed and saved, the app freezes or crashes completely. There seems to be some sort of race condition, maybe due to Core Data importing data in the background whilst the main thread is trying to perform a fetch, but I'm speculating. I've had trouble capturing any meaningful crash information, usually it's a SIGSEGV deep in the Core Data stack. The table below shows the actual order of events that happen when the detail table view controller is loaded: Main Thread Background Thread viewDidLoad Get JSON data (using AFNetworking) Create child NSManagedObjectContext (MOC) Parse JSON data Insert managed objects in child MOC Save child MOC Post import completion notification Receive import completion notification Save parent MOC Perform fetch and reload table view Delete old managed objects in child MOC Save child MOC Post deletion completion notification Receive deletion completion notification Save parent MOC Once the AFNetworking completion block is triggered when the JSON data has arrived, a nested NSManagedObjectContext is created and passed to an "importer" object that parses the JSON data and saves the objects to the Core Data store. The importer executes using the new performBlock method introduced in iOS 5: NSManagedObjectContext *child = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]; [child setParentContext:self.managedObjectContext]; [child performBlock:^{ // Create importer instance, passing it the child MOC... }]; The importer object observes its own MOC's NSManagedObjectContextDidSaveNotification and then posts its own notification which is observed by the detail table view controller. When this notification is posted the table view controller performs a save on its own (parent) MOC. I use the same basic pattern with a "deleter" object for deleting the old data after the new data for the day has been imported. This occurs asynchronously after the new data has been fetched by the fetched results controller and the detail table view has been reloaded. One thing I am not doing is observing any merge notifications or locking any of the managed object contexts or the persistent store coordinator. Is this something I should be doing? I'm a bit unsure how to architect this all correctly so would appreciate any advice.

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  • Updating Label on previously loaded view?

    - by fuzzygoat
    I am working on a simple app tab-bar based application that has two views. The first is the main application and the second is a simple instruction screen. What I am trying to do is create a update a label on that second screen as things change in the main app. Because the second screen is only simple with one label and some text I am not unloading it once its loaded. After the first viewDidLoad I can update the label just fine, but after that is there a way to catch successive view switches from the tab-bar menu so I can update the label? many thanks gary

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  • Problem with UITabBar + NavController in secondView viewDidLoad isn't called

    - by pbcoder
    My Application is a Tabbar with a navController in each of it's tabs. Now, the problem is to add a custom info button to the navController in the SecondView. I've created the App in InterfaceBuilder and entered the name of the nib to Load there. If I run my App now, the SecondView is shown, but the problem is, that the viewDidLoad is not called. http://www.freeimagehosting.net/image.php?9d8ed67dcc.png

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  • Need help using UIImagePNGRepresentation

    - by mustanggal511
    I'm trying to save a UIImageView image to a png file, and then use that file as a GLTexture. I'm having trouble with this, when I try to run my code in the simulator, XCode says it succeeded, but the simulator crashes with no error messages. Can someone help me with this? Here is my code: NSString *dataFilePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Picture.png"]; NSData *imageData = UIImagePNGRepresentation(imageView.image); [imageData writeToFile:dataFilePath atomically:YES]; // Load image into texture loadTexture("Picture.png", &Input, &renderer);

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  • Referencing file on disk from NSManagedObject

    - by Kamchatka
    Hello, What would be the best way to name a file associated to a NSManagedObject. The NSManagedObject will hold the URL to this file. But I need to create a unique filename for my file. Is there some kind of autoincrement id that I could use? Should I use mktemp (but it's not a temporary file) or try to convert the NSManagedObjectId to a filename? but I fear there will be special characters which might cause problem. What would you suggest?

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  • Question about select UITableViewCell fields

    - by Joaquin McCoy
    Hi guys, I've a custom UITableViewCell like this: +--------------------------+ | username | | | | --- <image> -- | | | | <like it> | +--------------------------+ It display an username, an image and a button "Like it" to like image. I don't want that the entire cell is selectable, I want a user can tap on "username" to see a new view that show username information. The same for image, when user tap on image, he could see the image in a new view. Now I can only select my entire cell. How can I implement something like this? Thanks. When you click on the username you'll see a view for user information. The entire cell is not selectable.

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  • Problem with writing mobilesubstrate plugins for iOS

    - by overboming
    I am trying to hooking message sending for iOS 3.2, I implement my own hook on a working ExampleHook program I find on the web. But my hook apparently caused segmentation fault everytime it hooks and I don't know why. I want to hook to [NSURL initWithString:(NSString *)URLString relativeToURL:(NSURL *)baseURL; and here is my related implementation static id __$GFWInterceptor_NSURL_initWithString2(NSURL<GFWInterceptor> *_NSURL, NSString *URLString, NSURL* baseURL){ NSLog(@"We have intercepted this url: %@",URLString); [_NSURL __HelloNSURL_initWithString:URLString relativeToURL:baseURL]; establish hook Class _$NSURL = objc_getClass("NSURL"); MSHookMessage(_$NSURL, @selector(initWithString:relativeToURL:), (IMP) &__$GFWInterceptor_NSURL_initWithString2, "__HelloNSURL_"); original method declaration - (void)__HelloNSURL_initWithString:(NSString *)URLString relativeToURL:(NSURL *)baseURL; and here is my gdb backtrace Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x74696e71 0x335625f8 in objc_msgSend () (gdb) bt 0 0x335625f8 in objc_msgSend () 1 0x32c05b1a in CFStringGetLength () 2 0x32c108a8 in _CFStringIsLegalURLString () 3 0x32b1c32a in -[NSURL initWithString:relativeToURL:] () 4 0x000877c0 in __$GFWInterceptor_NSURL_initWithString2 () 5 0x32b1c220 in +[NSURL URLWithString:relativeToURL:] () 6 0x32b1c1f4 in +[NSURL URLWithString:] () 7 0x3061c614 in createUniqueWebDataURL () 8 0x3061c212 in +[WebFrame(WebInternal) _createMainFrameWithSimpleHTMLDocumentWithPage:frameView:withStyle:editable:] () and apparently it hooks, but there is some memory issue there and I can't find anything to blame now

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  • Which pdf elements could cause crashes?

    - by Felixyz
    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 rendering code. From what I have been able to see, the crashing pages cause the rendering libraries to start allocating memory like mad until the app is killed. I have nothing else to help me pinpoint what triggers this process. It doesn't necessarily happen with the largest documents, or the ones with the most shapes. In fact, we haven't found any parameter that helps us predict which pages will crash and which not. Now we just discovered that running the pages through a consumer program that lets you merge docs gets rid of the problem, but I haven't been able to detect which attribute or element it is that is the key. Changing documents by hand is also not an option for us in the long run. We need to run an automated process on our server. I'm hoping someone with deeper knowledge about the pdf file format would be able to point me in a reasonable direction to look for document features that could cause this kind of behavior. All I've found so far is something about JBIG2 images, and I don't think we have any of those.

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  • OpenGLES - Rendering a background image only once and not wiping it

    - by chaosbeaker
    Hello, first time asking a question here but been watching others answers for a while. My own question is one for improving the performance of my program. Currently I'm wiping the viewFrameBuffer on each pass through my program and then rendering the background image first followed by the rest of my scene. I was wondering how I go about rendering the background image once, and only wiping the rest of the scene for updating/re-rendering. I tried using a seperate buffer but I'm not sure how to present this new buffer to the render buffer. // Set the current EAGLContext and bind to the framebuffer. This will direct all OGL commands to the // framebuffer and the associated renderbuffer attachment which is where our scene will be rendered [EAGLContext setCurrentContext:context]; glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer); // Define the viewport. Changing the settings for the viewport can allow you to scale the viewport // as well as the dimensions etc and so I'm setting it for each frame in case we want to change i glViewport(0, 0, screenBounds.size.width , screenBounds.size.height); // Clear the screen. If we are going to draw a background image then this clear is not necessary // as drawing the background image will destroy the previous image glClearColor(0.0f, 1.0f, 0.0f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); // Setup how the images are to be blended when rendered. This could be changed at different points during your // render process if you wanted to apply different effects glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); switch (currentViewInt) { case 1: { [background render:CGPointMake(240, 0) fromTopLeftBottomRightCenter:@"Bottom"]; // Other Rendering Code }} // Bind to the renderbuffer and then present this image to the current context glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer); [context presentRenderbuffer:GL_RENDERBUFFER_OES]; Hopefully by solving this I'll also be able to implement another buffer just for rendering particles as I can set them to always use a black background as their alpha source. Any help is greatly appreciated

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  • Can't append space at end of NSString

    - by Sam V
    I have a UITextView in which I want the initial value to be "@username " (notice the space after the username). This way the user can start typing right away without having to tap space. So I do: textView.text = [NSString stringWithFormat:@"@%@ ", username]; But it seems like it's impossible to have an NSString ending with a space (it always gets stripped out). Am I correct? Is there any workaround for this?

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  • OpenGL ES displaying HUD display Text can't be colored black on top of textured 3D objects

    - by ivanceras
    This is a follow-up of this question on here http://iphonedevelopment.blogspot.com/2010/02/drawing-hud-display-in-opengl-es.html It tackles on the HUD (heads up display) which is based on this tutorial http://stackoverflow.com/questions/2681102/opengl-es-displaying-hud-display-has-no-color-on-top-of-textured-3d-objects I wanted to set the "Text" in color BLACK, but it is more complicated than what I thought. Setting it to some other color other than black "glColor4f(0.0, 0.0, 0.0, 1.0);" is just fine. I assume that the culprit must be in the Blending function "glBlendFunc (GL_ONE, GL_ONE);" I experimented a lot of combinations with no luck. Has anyone experimented on this one on top of textured 3D in the backgrounds working?

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  • Retain, alloc, properties ... Topic to make your Obj-c life easier !

    - by gotye
    Hey everyone, The more I code, the more I get lost ... so I decided to create a topic entirely dedicated to the memory management for me (and others) not to waste hours understanding obj-c basics ... I'll update it as new questions are asked ! Okay below is some examples : // myArray is property (retain) myArray = otherArray; //myArray isn't a property myArray = otherArray; //myArray is a property (retain) myArray = [[NSArray alloc] init]; //myArray isn't a property myArray = [[NSArray alloc] init]; Could you explain to me what happens in every cases ? And especially the number 3 ;) Thanks for the time. Gotye.

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  • Custom UISlider Image not responding?

    - by Silent
    Hello all i have a custom image to replace the UISLider defult button image, all works fine image shows, it does not clip off. The problem is when i use the slider to move up and down the image dissapears and some how doesnt show up anymore only sometimes. could someone have a fix?

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