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  • What's safe to assume about the NSMutableArray / NSArray class cluster?

    - by andyvn22
    I know you shouldn't use this to decide whether or not to change an array: if ([possiblyMutable isKindOfClass:[NSMutableArray class]]) But say I'm writing a method and need to return either an NSMutableArray or an NSArray, depending on the mutability of possiblyMutable. The class using my method already knows whether or not it's acceptable to change the returned array. Whether or not it's acceptable to change the returned array directly correlates with whether or not it's acceptable to change possiblyMutable. In that specific case, is this code safe? It seems to me that if it's not acceptable to change the array, but we accidentally get a mutable array, it's ok, because the class using my method won't try to change it. And if it is acceptable to change the array, then we will always get possiblyMutable as an NSMutableArray (though this is the part I'm not entirely clear on). So... safe or not? Alternatives?

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  • 'EXC_BAD_ACCESS' When trying to access a variable?

    - by Nick Brooks
    I get an 'EXC_BAD_ACCESS' error when trying to access variable in a function other than the one it was set in: NSLog(@"Commening search (%@)",sessionID); // This causes it The variable is set in the 'awakeFromNib' function: //Retrieve Session-ID sessionID = [self getSessionID]; The variable itself is defined in the header: NSString *sessionID;

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  • How to debug KVO

    - by user8472
    In my program I use KVO manually to observe changes to values of object properties. I receive an EXC_BAD_ACCESS signal at the following line of code inside a custom setter: [self willChangeValueForKey:@"mykey"]; The weird thing is that this happens when a factory method calls the custom setter and there should not be any observers around. I do not know how to debug this situation. Update: The way to list all registered observers is observationInfo. It turned out that there was indeed an object listed that points to an invalid address. However, I have no idea at all how it got there. Update 2: Apparently, the same object and method callback can be registered several times for a given object - resulting in identical entries in the observed object's observationInfo. When removing the registration only one of these entries is removed. This behavior is a little counter-intuitive (and it certainly is a bug in my program to add multiple entries at all), but this does not explain how spurious observers can mysteriously show up in freshly allocated objects (unless there is some caching/reuse going on that I am unaware of). Modified question: How can I figure out WHERE and WHEN an object got registered as an observer? Update 3: Specific sample code. ContentObj is a class that has a dictionary as a property named mykey. It overrides: + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)theKey { BOOL automatic = NO; if ([theKey isEqualToString:@"mykey"]) { automatic = NO; } else { automatic=[super automaticallyNotifiesObserversForKey:theKey]; } return automatic; } A couple of properties have getters and setters as follows: - (CGFloat)value { return [[[self mykey] objectForKey:@"value"] floatValue]; } - (void)setValue:(CGFloat)aValue { [self willChangeValueForKey:@"mykey"]; [[self mykey] setObject:[NSNumber numberWithFloat:aValue] forKey:@"value"]; [self didChangeValueForKey:@"mykey"]; } The container class has a property contents of class NSMutableArray which holds instances of class ContentObj. It has a couple of methods that manually handle registrations: + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)theKey { BOOL automatic = NO; if ([theKey isEqualToString:@"contents"]) { automatic = NO; } else { automatic=[super automaticallyNotifiesObserversForKey:theKey]; } return automatic; } - (void)observeContent:(ContentObj *)cObj { [cObj addObserver:self forKeyPath:@"mykey" options:0 context:NULL]; } - (void)removeObserveContent:(ContentObj *)cObj { [cObj removeObserver:self forKeyPath:@"mykey"]; } - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { if (([keyPath isEqualToString:@"mykey"]) && ([object isKindOfClass:[ContentObj class]])) { [self willChangeValueForKey:@"contents"]; [self didChangeValueForKey:@"contents"]; } } There are several methods in the container class that modify contents. They look as follows: - (void)addContent:(ContentObj *)cObj { [self willChangeValueForKey:@"contents"]; [self observeDatum:cObj]; [[self contents] addObject:cObj]; [self didChangeValueForKey:@"contents"]; } And a couple of others that provide similar functionality to the array. They all work by adding/removing themselves as observers. Obviously, anything that results in multiple registrations is a bug and could sit somewhere hidden in these methods. My question targets strategies on how to debug this kind of situation. Alternatively, please feel free to provide an alternative strategy for implementing this kind of notification/observer pattern.

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  • should variable be released or not? iphone-sdk

    - by psebos
    Hi, I have the following piece of code from a book. There is this function loadPrefs where the NSString *userTimeZone is being released before the end of the function. Why? The string was not created with alloc and I assume that the stringForKey function returns an autoreleased NSString. Is this an error or am I missing something? Is it an error in the book? (I new into objective-C) In the documentation for stringForKey the only thing it mentions is: Special Considerations The returned string is immutable, even if the value you originally set was a mutable string. The code: - (void) loadPrefs { timeZoneName = DefaultTimeZonePref; NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; NSString *userTimeZone = [defaults stringForKey: TimeZonePrefKey]; if (userTimeZone != NULL) timeZoneName = userTimeZone; [userTimeZone release]; show24Hour = [defaults boolForKey:TwentyFourHourPrefKey]; } Thanks!!!!

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  • Why self.view is not available

    - by amok
    I have this code in the main view controller and it is working just fine and as I wanted. loadingActionSheet = [[UIActionSheet alloc] initWithTitle:@"Posting To Twitter..." delegate:nil cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:nil]; [loadingActionSheet showInView:self.view]; I wanted that code to be reusable from different part of the project so I moved it in a separate file (UIView based). The poblem that I am facing is that self.view is not available there and I don't know why because I am learning and I don't know enough to understand what I am missing. What do I have to do/add/change to have the actionsheet shown in my current view even if that code lives somewhere else?

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  • NSTextField enter to trigger action

    - by Chris
    I've been looking all over for a simple example of how to have an action (or button) be triggered when the enter key is hit in the text field. Should I subclass the text field? Would I need to set a delegate to call the action I need? Is there a way to catch the event in my main window controller class? If you could even just point me to the right direction that would be great. Thanks.

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  • how to hide backbar button in navigationbar in iPhone sdk

    - by Prerak
    Hi, In my iPhone App there are three views [ firstView secondView and thirdView} now I want to put Back Button in navigation bar in thirdview only which should take me to back secondview only for that i m writting this code in first view self.navigationItem.hidesBackButton:NO; and it shows the back button in both the views secondView and thirdView what I should do to hide back button in the the second view? please Help and Suggest. thanks.

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  • UILabel with custom font displays *wrong* custom font

    - by winsmith
    I'm using this method to embed custom fonts in my iPhone app. The embedding works: When I run the following code, the fonts are listed. (Currently, I'm embedding all family members of Myriad Pro in OTF format) for( NSString *familyName in [UIFont familyNames] ){ for( NSString *fntName in [UIFont fontNamesForFamilyName:familyName] ){ NSLog(@"%@", fntName); }} When I try to set the font of a label to MyriadPro or MyriadPro-Bold, this works just as expected. However, when I set the font to MyriadPro-BoldCond, the label is still set in MyriadPro-Bold instead of the condensed version. (The font names are correct, I checked.) My Code: [recommendationLabel setFont:[UIFont fontWithName:@"MyriadPro-BoldCond" size:140]]; recommendationLabel.adjustsFontSizeToFitWidth = YES; What's the deal?

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  • iPhone: Which are the most useful techniques for faster Bluetooth?

    - by Mike Howard
    Hi. I'm adding peer-to-peer bluetooth using GameKit to an iPhone shoot-em-up, so speed is vital. I'm sending about 40 messages a second each way, most of them with the faster GKSendDataUnreliable, all serializing with NSCoding. In testing between a 3G and 3GS, this is slowing the 3G down a lot more than I'd like. I'm wondering where I should concentrate my efforts to speed it up. How much slower is GKSendDataReliable? For the few packets that have to get there, would it be faster to send a GKSendDataUnreliable and have the peer send an acknowledgement so I can send again if I don't get the Ack within, say, 100ms? How much faster would it be to create the NSData instance using a regular C array rather than archiving with the NSCoding protocol? Is this serialization process (for about a dozen floats) just as slow as you'd expect from an object creation/deallocation overhead, or is something particularly slow happening? I heard that (for example) sending four seperate sets of data is much, much slower, than sending one piece of data four times the size. Would I make a significant saving by sending separate packets of data that wouldn't always go together in the same packet when they happen at the same time? Are there any other bluetooth performance secrets I've missed? Thanks for your help.

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  • What's the correct way to represent a linear process in CocoaTouch (UIKit)?

    - by UloPe
    I need to represent a linear process (think wizard) in an iPad app. In principle I could use a UINavigationController and just keep pushing new controllers for each step of the process. But this seems rather inefficient since the process I'm modeling has no notion of navigating backwards so all previous views would pointlessly stay around and use up resources. At the moment I keep adding and removing a subview to one "master" viewcontroller and basically swapping out the contents. This works but feels rather clunky and I hope there is some nicer way to achieve this. Additionally there needs to be an animated transition between the views. (I have this working at the moment via beginAnimations / commitAnimations)

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  • Objective C convention: When to use For and when to use With

    - by Howard
    According to the Apple guideline , seems it is confusing, e.g. for method viewWithTag In Java, I would have a method called getViewByTag // Java version, equivalent to viewWithTag in Obj-C But I also found there are some method like objectForKey, so why not just use objectWithKey instead? getObjectByKey or just get // Java version, equivalent to objectForKey, // but why not objectWithKey? Or not viewForKey above?

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  • Can't use method from class in other file

    - by user1833848
    I am not able to use one of my methods that i implemented in my tableviewcell file in my tableview controller implementation. I tried searching the web and xcode help with no luck. My codes looks like this: TableViewController.h: #import TableViewCell.h @interface TableViewController : UITableViewController @property (nonatomic, strong) IBOutlet UIBarButtonItem *A1Buy; @property (nonatomic, getter = isUserInteractionEnabled) BOOL userInteractionEnabled; - (IBAction)A1Buy:(UIBarButtonItem *)sender; TableViewController.m: @implementation A1ViewController @synthesize A1Buy = _A1Buy; @synthesize userInteractionEnabled; - (IBAction)A1Buy:(UIBarButtonItem *)sender { [TableViewCell Enable]; //this is where it gives an error } TableViewCell.h: @interface TableViewCell : UITableViewCell { BOOL Enable; BOOL Disable; } @property (nonatomic, getter = isUserInteractionEnabled) BOOL userInteractionEnabled; TableViewCell.m: @implementation TableViewCell; @synthesize userInteractionEnabled; - (BOOL) Enable { return userInteractionEnabled = YES; } - (BOOL) Disable { return userInteractionEnabled = NO; } As you can see i am trying to enable user interaction with a button, but Xcode only gives me errors like "class does not have this method" and stuff like that. All files are importet correctly so thats not why. Would appreciate any help. Thanks!

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  • Is there a way to detect non-movement (touch events) ?

    - by hyn
    Is there a way to detect a finger's non-movement by using a combination of UITouch events? The event methods touchesEnded and touchesCancelled are only fired when the event is cancelled or the finger lifted. I would like to know when a touch has stopped moving, even while it is still touching the screen.

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  • How do I reset the state of a view inside a tabbar?

    - by ABeanSits
    Hello CocoaTouch-Experts! This is a fairly straightforward question though my Googling session gave me nothing. How do I reset the state of a view hierarchy located in a tabbar programmatically? The behavior I want to replicate is when the user tapps on a tab twice. This causes the view located under that tab to return to it's initial state. The tab is "owned" by a UINavigationController and when the user reaches a certain point in the view hierarchy there is a button which I want to connect this behavior to. All my attempts have failed except calling on a method in AppDelegate which kills the view and adds it back to the UITabBarController again. But this does not feel like the right way to go. Thanks in advance. Best regards //Abeansits

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  • Loading an external NIB, how do I set the view property?

    - by Sheehan Alam
    If I am loading a view from another NIB, how do I set the File's Owner view property? IB is not letting me hook it up to my View Controller which is loading the external NIB. My NIB looks like this: File's Owner - Identity is set to LBRootViewController First Responder LBTableViewController - Identity is set to LBTableViewController, NIB Name is LBTableViewController

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  • Favourite Open Source iPhone apps

    - by objektivs
    I'm an aspiring iPhone developer and I'm looking for a significant OS iPhone codebase to see how others build apps. I'm especially interested in examples exhibiting some or all of the following: business/enterprise apps apps that interact with web services apps utilising XML apps using oauth or other authenticate Personally, I'm less interested in games, but feel free to include any examples for the benefit of others. I'm asking here because the usual places I've been looking (i.e. sourceforge) don't seem to have the kind of examples I'm looking for.

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  • Defined outlets, connected them, they all returns (null)

    - by Tom
    Hi! I'm trying to play with a WebView. I made an outlet: IBOutlet UIWebView *browser; Defined it as a property: @property (nonatomic, retain) IBOutlet UIWebView *browser; Synthethized it: @synthesize browser; Finally, I connected it in Interface Builder, really it is. Then I try to do something with it i.e.: [browser loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://apple.com"]]]; Or also: Etape *etape = [[Etape alloc] init]; NSString *html = [etape generateHTMLforEtape:[current_etape objectAtIndex:0]]; [browser loadHTMLString:html baseURL:nil]; [etape release]; I get no errors, I tried to Build & Analyse, no notices or warnings or errors.. I've been searching for one whole day, please help me :/ Thanks a lot! EDIT: Here's screenshots of my connections for my WebView: EDIT: That is how I call the view: DetailViewController *dvController = [[DetailViewController alloc] initWithNibName:@"DetailViewController" bundle:[NSBundle mainBundle]]; dvController.workflow_id = parent_id; Etape *etape = [[Etape alloc] init]; dvController.etapes = [etape getEtapes:parent_id]; [etape release]; [self.navigationController pushViewController:dvController animated:YES]; [dvController release];

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  • Displaying a "Loading..." screen in a UITableView like the AppStore App...

    - by Mugunth Kumar
    the App Store app and fairly a lot many apps display a view that says "Loading.." while the content is being retrieved. How can we do this? Should I remove the UITableView and call addSubView and then once the data is available, add the tableview back? Or is there any other shortcut? If my question is not clear, please see this image... http://www.flickr.com/photos/mugunthkumar/3774575906/ I want to know how to create a temporary loading view like this till my tableview contents are ready...

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