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  • should variable be retained or not? iphone-sdk

    - by psebos
    Hi, in the following piece of code I got from a book. The NSString *pPath which is defined in the class as an instance variable. @interface MainViewController : UIViewController { NSString *pPath; } In the implementation after being set it is being retained. I assume that with the assignment the object is automatically retained (because it is an NSString) and there is no need to additionally retain it. - (void) initPrefsFilePath { NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]; pPath = [documentsDirectory stringByAppendingPathComponent: @"flippingprefs.plist"]; [pPath retain]; }

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  • How to cancel a touch sequence

    - by Alex
    I have an UIImage view that responds to touch events. I want to cancel the touch sequence if the touch goes outside of certain bounds. How can I do that? I know that I can inspect the coordinates of the touch object, what I don't know is how to cancel the sequence. I don't see any event in the API that allows for that.

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  • Converting RGB values to CMYK

    - by llk
    Hi all, I have RGB values that I need to convert into CMYK values. I'm using the iPhone SDK to try and do this. I have tried a couple of things, but cannot either get the values to be anything other than 0 or 1, or the K element is completely wrong (showing up as a negative number). Any help would be a life saver! Thanks in advance!

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  • in playgame button Game Get freezed

    - by bmindhacker
    Hey guys i have done a game in cocos2d.And now i am stuck .i have a menu scene and a game scene. In menu scene i have a button named "Play Game". when i press this button game starts perfectly after game over i have a button named "Go back to main menu" that is used to take back to main menu scene now after game over when i click "PlayGame" button game does not perform any action and get freeze. please please help me guys i will be really thankful to you.

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  • Get highlighted state for NSButtonCell

    - by dvg
    I have a NSTableView that contains a NSButtonCell in one of the columns. To draw a custom background in neighbor cells (based on NSTextFieldCell) I use isHighlighted method: - (void)drawWithFrame:(NSRect)cellFrame inView:(NSView *)controlView { if ([self isHighlighted]) { //here I draw the cell background But for NSButtonCell isHighlighted shows only the button pressed state. How to determine when the NSButtonCell is selected, i.e. when it's highlighted in the row?

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  • Specific Strings And NSScanner

    - by Garry
    I need to determine whether a string (sourceString) contains another string (queryString) and if it does, at what offset. I'm guessing that NSScanner might do the trick but I don't fully understand the documentation. Let's say sourceString = @"What's the weather in London today?" If I set queryString to equal @"What's the weather", I'd like a method that would determine that, in this case, YES (sourceString does contain queryString) and the offset is 0 (i.e. at the start of sourceString). Any suggestions?

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  • IOS SDK : first advices for beginners

    - by VdesmedT
    I too often answer the same kind of questions regarding basic topics like memory management, UITableView, Interface Orientation, MVC, etc... I understand very well that everyone starting with that SDK is too exited about getting its hand on it but a few reading would save them hours of debugging and the frustration that come along with the feeling that "We miss something here". I'd like experience users to share the few small articles, white papers, docs, book chapters that helps other save their time and avoid frustration. My first vote would be for : IOS Memory Management Guide View Controller Programming Guide Table View Guide And as a General recommendation, read the Overview section that come along with every class documention in the reference library, they contains most of what you need to know to avoid big traps !

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  • Can't get Jacobi algorithm to work in Objective-C

    - by Chris Long
    Hi, For some reason, I can't get this program to work. I've had other CS majors look at it and they can't figure it out either. This program performs the Jacobi algorithm (you can see step-by-step instructions and a MATLAB implementation here). BTW, it's different from the Wikipedia article of the same name. Since NSArray is one-dimensional, I added a method that makes it act like a two-dimensional C array. After running the Jacobi algorithm many times, the diagonal entries in the NSArray (i[0][0], i[1][1], etc.) are supposed to get bigger and the others approach 0. For some reason though, they all increase exponentially. For instance, i[2][4] should equal 0.0000009, not 9999999, while i[2][2] should be big. Thanks in advance, Chris NSArray+Matrix.m @implementation NSArray (Matrix) @dynamic offValue, transposed; - (double)offValue { double sum = 0.0; for ( MatrixItem *item in self ) if ( item.nonDiagonal ) sum += pow( item.value, 2.0 ); return sum; } - (NSMutableArray *)transposed { NSMutableArray *transpose = [[[NSMutableArray alloc] init] autorelease]; int i, j; for ( i = 0; i < 5; i++ ) { for ( j = 0; j < 5; j++ ) { [transpose addObject:[self objectAtRow:j andColumn:i]]; } } return transpose; } - (id)objectAtRow:(NSUInteger)row andColumn:(NSUInteger)column { NSUInteger index = 5 * row + column; return [self objectAtIndex:index]; } - (NSMutableArray *)multiplyWithMatrix:(NSArray *)array { NSMutableArray *result = [[NSMutableArray alloc] init]; int i = 0, j = 0, k = 0; double value; for ( i = 0; i < 5; i++ ) { value = 0.0; for ( j = 0; j < 5; j++ ) { for ( k = 0; k < 5; k++ ) { MatrixItem *firstItem = [self objectAtRow:i andColumn:k]; MatrixItem *secondItem = [array objectAtRow:k andColumn:j]; value += firstItem.value * secondItem.value; } MatrixItem *item = [[MatrixItem alloc] initWithValue:value]; item.row = i; item.column = j; [result addObject:item]; } } return result; } @end Jacobi_AlgorithmAppDelegate.m // ... - (void)jacobiAlgorithmWithEntry:(MatrixItem *)entry { MatrixItem *b11 = [matrix objectAtRow:entry.row andColumn:entry.row]; MatrixItem *b22 = [matrix objectAtRow:entry.column andColumn:entry.column]; double muPlus = ( b22.value + b11.value ) / 2.0; muPlus += sqrt( pow((b22.value - b11.value), 2.0) + 4.0 * pow(entry.value, 2.0) ); Vector *u1 = [[[Vector alloc] initWithX:(-1.0 * entry.value) andY:(b11.value - muPlus)] autorelease]; [u1 normalize]; Vector *u2 = [[[Vector alloc] initWithX:-u1.y andY:u1.x] autorelease]; NSMutableArray *g = [[[NSMutableArray alloc] init] autorelease]; for ( int i = 0; i <= 24; i++ ) { MatrixItem *item = [[[MatrixItem alloc] init] autorelease]; if ( i == 6*entry.row ) item.value = u1.x; else if ( i == 6*entry.column ) item.value = u2.y; else if ( i == ( 5*entry.row + entry.column ) || i == ( 5*entry.column + entry.row ) ) item.value = u1.y; else if ( i % 6 == 0 ) item.value = 1.0; else item.value = 0.0; [g addObject:item]; } NSMutableArray *firstResult = [[g.transposed multiplyWithMatrix:matrix] autorelease]; matrix = [firstResult multiplyWithMatrix:g]; } // ...

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  • Hiding UITableViewCell

    - by live2dream95
    Is there a way to hide a UITableView cell? I'm looking for some property or method I can invoke on the UITableViewCell returned by a synchronous cellForRowAtIndexPath() to hide it and make it unselectable by the user.

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  • Nested functions not allowed in drawrect problem

    - by Martin
    I have a custom view onto which I draw some graphics from the drawrect function, which works fine. However I like to draw based on the contens of an array I pass on the the view just before I do a setNeedsDisplay. In the drawRect function I try to access the array but then I get a nested functions error which I do not understand. Here's my code: // // MyView.h // window // #import <UIKit/UIKit.h> @interface MyView : UIView { NSArray * nary; } @property (nonatomic, copy) NSArray *nary; @end // // MyView.m // window // #import "MyView.h" @implementation MyView @synthesize nary; CGContextRef c; CGFloat black[4] = {0.0f, 0.0f, 0.0f, 1.0f}; - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { // Initialization code } return self; } - (void)drawRect:(CGRect)rect { c = UIGraphicsGetCurrentContext(); CGContextSetStrokeColor(c, black); NSLog(@"mview"); NSArray *ns = [nary objectAtIndex:0]; } - (void)dealloc { [super dealloc]; } @end

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  • Is it possible to create a UINavigationController within a ModalPopup?

    - by aloo
    Hi I have a modalViewController that I am popping up using [self presentModalViewController:myController animated:YES]; I have an event occurring within myController which I would like to result in another controller being pushed onto the navigation stack ON TOP OF myController (which again has been presented modally). How can I do this? I have tried the following from within myController: UINavigationController* navController = [[UINavigationController alloc] initWithRootViewController:self]; NewController* n = [[NewController alloc] init]; [navController pushViewController:n animated:YES]; [n release]; This does not work however....

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  • iPhone UIImage Display Controller

    - by Bill Shiff
    Hello, I would like to be able to display a UIImage from within my app and support a lot of the functionality available in the built-in Photos app (i.e., pinch-to-zoom, pan, etc). I don't really want to write a bunch of code that someone has already written, so I'm wondering if there is a library out there already that I could just import into my project. I'm aware of the Three20 project, but I don't want to import a huge library if I don't have to. Is anyone aware of an available library that's already out there for displaying UIImages? Or part of some open-source project that can be pulled out on its own? Thanks!

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  • Stored Procedure or calculations via IQueryable?

    - by Shawn Mclean
    This is a question that is based on choosing performance over design practices. If I have a method that will be executed many times a second; public static IQueryable<IPerson> InRadius(this IQueryable<IPerson> query, Coordinate center, double radius) { return (from u in query where CallHeavyMathFormula(u, center, radius) select u); } This extension method for IQueryable generates a SQL that does some heavy maths calculation (Cosine, Sine, etc). This would mean the application sends 1-2KB of sql to the server per call. I've heard of placing all application logic, in your application. I also would like to change to a database such as azure or one of those scalable databases in the future. How do I handle something like this? Should I leave it as it is now or write stored procedures? How do applications like twitter or facebook do it?

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  • Show NSSegmentedControl menu when segment clicked, despite having set action

    - by enchilada
    My question is based on another question. Instead of repeating a bunch of stuff, I hope it's okay that I refer you to that other question instead: http://stackoverflow.com/questions/1203698/show-nssegmentedcontrol-menu-when-segment-clicked-despite-having-set-action/ My question is: How would the code within [self showGearMenu] look like, i.e. how would one actually use the popUpContextMenu:withEvent:forView method to accomplish what the poster of the other question wants? I ask because it seems that the question was resolved for the poster, but he never shared with us how he actually popped up the menu :)

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  • Navigation Controller not Pushing/Popping View Controllers

    - by senfo
    I'm working on a view-based iPhone app that has the following flow: search - (list | map) - details To accomplish the transitions between views, I have a UINavigationController, with the search view controller being the root. After a user performs a search, I transition to a view with a segmented control, which acts as a tab to switch between the list and map functionality (per a suggestion from a related question I had). This view contains a UIViewController, which allows me to switch between the list/map view when a user taps the segmented control. I'm fine up until this point. As you can see from the above mentioned flow, I would like to provide the ability to transition into a details view. Each row of my table in the list view contains a details disclosure button for allowing the user to drill down into a details view. The problem is, when I try to push the details view onto the navigation stack, nothing happens. Below is the delegate method (from my list view controller) to handle the details disclosure button being tapped. I've set up break points, so I know the code is running. The navigation controller simply doesn't want to push the detailsController onto the stack (my guess is that I don't have a pointer to the correct UINavigationController). - (void)tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath { if (detailController == nil) { detailController = [[DetailsViewController alloc] init]; } [self.navigationController pushViewController:detailController animated:YES]; } Assuming I was probably missing a pointer to the navigation controller, I exposed a UINavigation property on my list and map views (navigationController is readonly) and initialized them with a pointer to the navigation controller from my SwitchViewController (the view responsible for switching between list/map views when a user changes the value of the segmented control). Unfortunately, this did not solve the problem. Am I on the right track? If so, how do I see to it that my view has a pointer to the correct navigation controller? Should I add a delegate, which allows me to call a function in the SwitchViewController that transitions into the details view (this seems messy)?

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  • How do I get current network location name?

    - by Devara Gudda
    In system network preference there are some location names.How to get the current or active network location name and list of all network locations? I guess SystemConfiguration.framework supports this but i didn't get exactly which API to use.Thanks in advance for your answer. RegardsDevara Gudda

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  • Fast (de)serialization on iPhone

    - by Jacob Kuypers
    I'm developing a game/engine for iPhone OS. It's the first time I'm using Objective-C. I made my own binary format for geometry data and for textures I'm focusing on PVRTC. That should be the optimal approach as far as speed and space are concerned. I really want to keep loading time to a minimum and - if possible - be able to save very fast as well. So now I'm trying to make my "Entity" stuff persistent without sacrificing performance. First I wanted to use NSKeyedArchiver. From what I've heard, it's not very fast. Also, what I want to serialize is mostly structs made of floats with some ints and strings, so there isn't really a need for all that "object graph" overhead. NSArchiver would have been more appropriate, but they kicked that off the iphone for some reason. So now I'm thinking about making my own serialization scheme again. Am I wrong in thinking that NSKeyedArchiver is slow (I only read that, haven't tested it myself)? If so, what's the best way to encode/decode structs (with no pointers, mostly floats) without sacrificing speed?

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  • How to set the the height of cell progamatically without using nib file ?

    - by srikanth rongali
    This is my program - (void)viewDidLoad { [super viewDidLoad]; // Uncomment the following line to display an Edit button in the navigation bar for this view controller. self.title = @"Library"; self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Close" style:UIBarButtonItemStyleBordered target:self action:@selector(close:)]; // self.tableView.rowHeight = 80; } -(void)close:(id)sender { // } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease]; UILabel *dateLabel = [[UILabel alloc]init]; dateLabel.frame = CGRectMake(85.0f, 6.0f, 200.0f, 20.0f); dateLabel.tag = tag1; [cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator]; cell.contentView.frame = CGRectMake(0.0f, 0.0f, 320.0f, 80.0f); [cell.contentView addSubview:dateLabel]; [dateLabel release]; } // Set up the cell... //[(UILabel *)[cell viewWithTag:tag1] setText:@"Date"]; cell.textLabel.text = @"Date"; return cell; } I am setting the frame size of cell in tableView: but the cell is in default size only. I mean the height I set was 80 but it was not set as 80 height. How can I make it. Thank You

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  • How do you call a method for an Objective-C object's superclass from elsewhere?

    - by executor21
    If you're implementing a subclass, you can, within your implementation, explicitly call the superclass's method, even if you've overridden that method, i.e.: [self overriddenMethod]; //calls the subclass's method [super overriddenMethod]; //calls the superclass's method What if you want to call the superclass's method from somewhere outside the subclass's implementation, i.e.: [[object super] overriddenMethod]; //crashes Is this even possible? And by extension, is it possible to go up more than one level within the implementation, i.e.: [[super super] overriddenMethod]; //will this work?

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