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  • Using Interface Builder tags

    - by pat
    I'm using interface builder's tag feature to access some UILabels I'm instantiating in a xib file. Since this a UITextViewCell I want to avoid superfluous method calls, but I want to do it right too. Thus when I do: UILabel *label = (UILabel *)[cell viewWithTag:1]; I'm wondering if I should wrap it up like so: if([[cell viewWithTag:1] isKindOfClass [UITableViewCell class]]) { UILabel *label = (UILabel *)[cell viewWithTag:1]; } Any discussion on this would be appreciated. Thanks

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  • Few iPhone noob questions

    - by mshsayem
    Why should I declare local variables as 'static' inside a method? Like: static NSString *cellIdentifier = @"Cell"; Is it a performance advantage? (I know what 'static' does; in C context) What does this syntax mean?[someObj release], someObj = nil; Two statements? Why should I assign nil again? Is not 'release' enough? Should I do it for all objects I allocate/own? Or for just view objects? Why does everyone copy NSString, but retains other objects (in property declaration)? Yes, NSStrings can be changed, but other objects can be changed also, right? Then why 'copy' for just NSString, not for all? Is it just a defensive convention? Shouldn't I release constant NSString? Like here:NSString *CellIdentifier = @"Cell"; Why not? Does the compiler allocate/deallocate it for me? In some tutorial application I observed these (Built with IB): Properties(IBOutlet, with same ivar name): window, someLabel, someTextField, etc etc... In the dealloc method, although the window ivar was released, others were not. My question is: WHY? Shouldn't I release other ivars(labels, textField) as well? Why not? Say, I have 3 cascaded drop-down lists. I mean, based on what is selected on the first list, 2nd list is populated and based on what is selected on the second list, 3rd list is populated. What UI components can reflect this best? How is drop-down list presented in iPhone UI? Tableview with UIPicker? When should I update the 2nd, 3rd list? Or just three labels which have touch events? Can you give me some good example tutorials about Core-Data? (Not just simple data fetching and storing on 2/3 tables with 1/2 relationship) How can I know whether my app is leaking memory? Any tools?

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  • Core Data: fetch an NSManagedObject by its properties

    - by niklassaers
    Hi guys, I have an object NetworkMember that has no attributes but is defined by its relationships Person, Network, Level and Role. In my app, I've found all the four relationships, but I want to make sure not to double-register my NetworkMember, thus I'd like to search for this NSManagedObject before instantiating it. How should I write a query that queries for an NSManagedObject just consisting of relationships? Cheers Nik

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  • CGGradient in an CGPath

    - by catlan
    Is it possible to draw a gradient in a path on the iPhone? I'm looking for a replacement of the mac os x method -drawInBezierPath:(NSBezierPath *)path relativeCenterPosition:(NSPoint)relativeCenterPosition of NSGradient.

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  • Remove year component from NSDateFormatter style

    - by JK
    I would like to present a date in the kCFDateFormatterFullStyle, but without the year. Is there any way to remove the year component from this style? My app requires localization so practically I cannot programmatically set the format string for all locales. I have come accross a solution which removes the "y" characters from the format string returned by the built in styles. Unfortunately, this is not acceptable as the year components are not represented by "y" in some other languages like Japanese. Any suggestions to get the kCFDateFormatterFullStyle without the year would be great! Thanks.

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  • Release Quickie

    - by Meltemi
    How to succinctly handle this situation. I'm not properly releasing contactDictionary in the if statement... NSNumber *pIDAsNumber; ... NSMutableDictionary *contactDictionary = [NSMutableDictionary dictionaryWithDictionary:[defaults dictionaryForKey:kContactDictionary]]; if (!contactDictionary) { contactDictionary = [[NSMutableDictionary alloc] initWithCapacity:1]; } [contactDictionary setObject:pIDAsNumber forKey:[myClass.personIDAsNumber stringValue]]; [defaults setObject:contactDictionary forKey:kContactDictionary];

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  • iPhone: Does it ever make sense for an object to retain its delegate?

    - by randombits
    According to the rules of memory management in a non garbage collected world, one is not supposed to retain a the calling object in a delegate. Scenario goes like this: I have a class that inherits from UITableViewController and contains a search bar. I run expensive search operations in a secondary thread. This is all done with an NSOperationQueue and subclasses NSOperation instances. I pass the controller as a delegate that adheres to a callback protocol into the NSOperation. There are edge cases when the application crashes because once an item is selected from the UITableViewController, I dismiss it and thus its retain count goes to 0 and dealloc gets invoked on it. The delegate didn't get to send its message in time as the results are being passed at about the same time the dealloc happens. Should I design this differently? Should I call retain on my controller from the delegate to ensure it exists until the NSOperation itself is dealloc'd? Will this cause a memory leak? Right now if I put a retain on the controller, the crashes goes away. I don't want to leak memory though and need to understand if there are cases where retaining the delegate makes sense. Just to recap. UITableViewController creates an NSOperationQueue and NSOperation that gets embedded into the queue. The UITableViewController passes itself as a delegate to NSOperation. NSOperation calls a method on UITableViewController when it's ready. If I retain the UITableViewController, I guarantee it's there, but I'm not sure if I'm leaking memory. If I only use an assign property, edge cases occur where the UITableViewController gets dealloc'd and objc_msgSend() gets called on an object that doesn't exist in memory and a crash is imminent.

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  • How can I consolidate deferred/delayed calls in Objective-C ?

    - by thrusty
    I'd like to ensure that certain maintenance tasks are executed "eventually". For example, after I detect that some resources might no longer be used in a cache, I might call: [self performSelector:@selector(cleanupCache) withObject:nil afterDelay:0.5]; However, there might be numerous places where I detect this, and I don't want to be calling cleanupCache continuously. I'd like to consolidate multiple calls to cleanupCache so that we only periodically get ONE call to cleanupCache. Here's what I've come up with do to this-- is this the best way? [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(cleanupCache) object:nil]; [self performSelector:@selector(cleanupCache) withObject:nil afterDelay:0.5];

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  • iPhone UIView element similar to the lock screen

    - by Travis
    Does anyone know if there is an open source project for an UIView element that acts in a similar way to the lock screen for the iPhone. I am working on an app that has some sensitive data, and I want to add another layer of comfort for users, to be able to setup a 4 digit pin number on the app. I've seen apps like LoseIt and Weightbot that have similar functionality. There isn't any element for this in the UI Library from what I've been able to find, and was hoping some kind soul might have open sourced something similar to this. Thanks in advance!!!

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  • How to edit an default Xcode template?

    - by HelloMoon
    When I create an NSObject subclass, I always get an empty implementation. There are some things I always put in my code like pragma marks and -dealloc methods. I prefer to just delete stuff that I don't need over writing it with typos from scratch every time I need it. I need -dealloc and -init almost always, but they don't ship with the default template. Is there a way to customize what's in there?

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  • NSString stringWithFormat question

    - by John Smith
    I am trying to build a small table using NSString. I cannot seem to format the strings properly. Here is what I have [NSString stringWithFormat:@"%8@: %.6f",e,v] where e is an NSString from somewhere else, and v is a float. What I want is output something like this: Grapes: 20.3 Pomegranates: 2.5 Oranges: 15.1 What I get is Grapes:20.3 Pomegranates:2.5 Oranges:15.1 How can I fix my format to do something like this?

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  • Tab-Bar not hiding on all views

    - by Sheehan Alam
    I have a tab-bar controller that loads a RootView. The RootView has 4 buttons that will load a UITableView I don't want my tab-bar to be visible in the RootView so I added the following code: -(void)viewDidLoad{ self.hidesBottomBarWhenPushed = YES; } When I initially load the app the tab-bar doesn't appear, but when I click on a button, and go back to the RootView the tab-bar still appears. I have tried placing this code in viewWillAppear and other application lifecycle methods but no luck.

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  • Core Data fetch request with array

    - by JK
    I am trying to set a fetch request with a predicate to obtain records in the store whose identifiers attribute match an array of identifiers specified in the predicate e.g. NSString *predicateString = [NSString stringWithFormat:@"identifier IN %@", employeeIDsArray]; The employeeIDsArray contains a number of NSNumber objects that match IDs in the store. However, I get an error "Unable to parse the format string". This type of predicate works if it is used for filtering an array, but as mentioned, fails for a core data fetch. How should I set the predicate please?

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  • How to view existing data in Core Data?

    - by mshsayem
    Well, may be this question is silly, but I couldn't find a way (except programmatically). I built a project (for iPhone OS 3.0) which uses Core Data. The xcdatamodel file shows the schema description, but I want to see the data in tabular form (like the management studio for mssql server or phpmyadmin for mysql). Is there any way (except coding)? What is that? Also, which file (in disk/device) those data are stored into? [ I built the tutorial (from apple) on Core Data, named Locations. They used this line somewhere in the code: NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"Locations.sqlite"]]; But, I did not see any "xxxxx.sqlite" file in project location (nor in the disk).]

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  • Why are the default UI controls in my iPhone app blurred?

    - by Tom H
    Why would the default iPhone interface elements, specifically the UISwitch (unmodified) and a UISegmentedControl appear slightly blurred? I have not changed them or called any private APIs. This blurring occurs when I run it both in the simulator and when I load it on my iPod Touch, so I don't think it's a one off drawing glitch. These elements were created via some code (initWithFrame:) not in interface builder. Here is a screenshot of the blurring in the simulator: http://drp.ly/14rS6a It looks similar on the actual device. Thanks for your help

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  • How to get a long url from a short url

    - by JK
    I would like to determine what the long url of a short url is. I have tried using http HEAD requests, but very few of the returned header fields actually contain any data pertaining to the destination/long url. Is there: 1. Any way to determine the long url? 2. If so, can it be done without downloading the body of the destination? Thank you

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  • NSOutlineView not redrawing

    - by Septih
    Hello, I have an NSOutlineView with checkboxes. I have the checkbox state bound to a node item with the key shouldBeCopied. In the node item I have the getters and setters like so: -(BOOL)shouldBeCopied { if([[self parent] shouldBeCopied]) return YES; return shouldBeCopied; } -(void)setShouldBeCopied:(BOOL)value { shouldBeCopied = value; if(value && [[self children] count] > 0) [[self delegate] reloadData]; } The idea here is that if the parent is checked, so should the children. The problem I'm having is that when I check the parent, it does not update that view of the children if they are already expanded. I can understand that it should not be updated by the bindings because i'm not actually changing the value. But should reloadData not cause the bindings to re-get the value, thus calling -shouldBeCopied for the children? I have tried a few other things such as -setNeedsDisplay and -reloadItem:nil reloadChildren:YES but none work. I've noticed that the display gets refreshed when I swap to xcode and then back again and that's all I want, so how do I get it to behave that way?

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  • Adding methods to an Objective C class interface is optional?

    - by Steve the Plant
    Coming from a C++ background, one thing that confuses me about Objective C is the fact that you can add a method to a class without actually specifying it in the class interface. So I had a barrage of questions: Why would someone choose to not add the method in the class interface? Is it simply because of visibility? Methods without a declaration in the interface are private? Is declaring methods in a class interface just optional? Is it different for overriding a base class' method?

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  • Checking an empty Core Data relationship (SQLite)

    - by rwat
    I have a to-many relationship in my data model, and I'd like to get all the objects that have no corresponding objects in the relationship. For example: Customer - Purchases I want to get all Customers that have 0 Purchases. I've read somewhere that I could use "Purchases[SIZE] = 0", but this gives me an unsupported function expression error, which I think means it doesn't work with a SQLite backing store (which I don't want to switch from, due to some performance constraints). Any ideas?

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  • How to use NSScanner?

    - by Zopi
    Hi, I've just read Apple's docu of NSScanner. I'm trying to get the integer of that string: @"user logged (3 attempts)". I can't find any example, how to scan within parentheses. Any ideas? Here's the code: NSString *logString = @"user logged (3 attempts)"; NSScanner *aScanner = [NSScanner scannerWithString:logString]; [aScanner scanInteger:anInteger]; NSLog(@"Attempts: %i", anInteger); Regrads, Ruby

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  • UTC-8 conversion

    - by leachianus
    Hey guys, I am grabbing a JSON array and storing it in a NSArray, however it includes JSON encoded UTF-8 strings, for example pass\u00e9 represents passé. I need a way of converting all of these different types of strings into the actual character. I have an entire NSArray to convert. Or I can convert it when it is being displayed, which ever is easiest. I found this chart http://tntluoma.com/sidebars/codes/ is there a convenience method for this or a library I can download? thanks, BTW, there is no way I can find to change the server so I can only fix it on my end...

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  • Calling NSFetchedResultsController & CoreData experts

    - by JK
    I am having a few nagging issues with NSFetchedResultsController and CoreData, any of which I would be very grateful to get help on. Issue 1 - Updates: I update my store on a background thread which results in certain rows being delete, inserted or updated. The changes are merged into the context on the main thread using the "mergeChangesFromContextDidSaveNotification:" method. Inserts and deletes are updated properly, but updates are not (e.g. the cell label is not updated with the change) although I have confirmed the updates to come through the contextDidSaveNotifcation, exactly like the inserts and deleted. My current workaround is to temporarily change the staleness interval of the context to 0, but this does not seem like the ideal solution. Issue 2 - Deleting objects: My fetch batch size is 20. If an object is deleted by the background thread which is in the first 20 rows, everything works fine. But if the object is after the first 20 rows and the table is scrolled down, a "CoreData could not fulfill a fault" error is raised. I have tried resaving the context and reperforming the frc fetch - all to no avail. Note: In this scenario, the frc delegate method "didChangeObject...." is not called for the delete - I assume this is because the object in question had not been faulted at that time (as it is was outside the initial fetch range). But for some reason, the context still thinks the object is around, although is has been deleted from the store. Issue 3 - Deleting sections : When the deletion of a row leads to the deletion of a section, I have gotten the "invalid number of rows in section???" error. I have worked around this by removing the "reloadSection" line from the NSFetchedResultsChangeMove: section and replacing it with "[tableView insertRowsAtIndexPaths...." This seems to work, but once again, I am not sure if this is the best solution. Any help would be greatly appreciated. Thank you!

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