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  • (iphone) maintaining CGContextRef or CGLayerRef is a bad idea?

    - by Eugene
    Hi, I need to work with many images, and I can't hold them as UIImage in memory because they are too big. I also need to change colors of image and merge them on the fly. Creating UIImage from underlying NSData, change color, and combine them when you can't have many images on memory is fairly slow. (as far as I can get) I thought maybe I can store underlying CGLayerRef(for image that will be combined) and CGContextRef(the resulting combined image). I am new to drawing world, and not sure if CGLayerRef or CGContextRef is smaller in memory than UIImage. I recently heard that w*h image takes up w*h*4 bytes in memory. Does CGLayerRef or CGContextRef also take up that much memory? Thank you

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  • How to save an animated image to iPhone's photos album?

    - by OpenThread
    I created an animated image, and it animates properly in an UIImageView: - (void)viewDidLoad { [super viewDidLoad]; UIImage *image1 = [UIImage imageNamed:@"apress_logo"]; UIImage *image2 = [UIImage imageNamed:@"Icon"]; UIImage *animationImage = [UIImage animatedImageWithImages:[NSArray arrayWithObjects:image1, image2, nil] duration:0.5]; UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)]; imageView.image = animationImage; [self.view addSubview:imageView]; } But if saved to photos album, it couldn't animate agian: UIImageWriteToSavedPhotosAlbum(animationImage, self, @selector(imageSavedToPhotosAlbum:didFinishSavingWithError:contextInfo:), nil); So is there any solution to save an animated image to photos album? Special thanks!

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  • What's a good way to have sample data on the iPhone/iPad?

    - by MikeN
    I have an iPad application that pulls in all of its data from an external web service. I am working on building in a demo mode that will use a cache of demo data stored on the device so it can be demoed and tried out without the web service connection (or an internet connection.) Is there a project or good practices standard to follow to model this type of sample data? I'm expecting JSON arrays/Dictionaries back from my web service, how could I build a function that uses hardcoded data to create the NSMutableData object I'd expect to get back from a JSON web request?

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  • Beginner having difficulty with SQL query

    - by Vulcanizer
    Hi, I've been studying SQL for 2 weeks now and I'm preparing for an SQL test. Anyway I'm trying to do this question: For the table: 1 create table data { 2 id int, 3 n1 int not null, 4 n2 int not null, 5 n3 int not null, 6 n4 int not null, 7 primary key (id) 8 } I need to return the relation with tuples (n1, n2, n3) where all the corresponding values for n4 are 0. The problem asks me to solve it WITHOUT using subqueries(nested selects/views) It also gives me an example table and the expected output from my query: 01 insert into data (id, n1, n2, n3, n4) 02 values (1, 2,4,7,0), 03 (2, 2,4,7,0), 04 (3, 3,6,9,8), 05 (4, 1,1,2,1), 06 (5, 1,1,2,0), 07 (6, 1,1,2,0), 08 (7, 5,3,8,0), 09 (8, 5,3,8,0), 10 (9, 5,3,8,0); expects (2,4,7) (5,3,8) and not (1,1,2) since that has a 1 in n4 in one of the cases. The best I could come up with was: 1 SELECT DISTINCT n1, n2, n3 2 FROM data a, data b 3 WHERE a.ID <> b.ID 4 AND a.n1 = b.n1 5 AND a.n2 = b.n2 6 AND a.n3 = b.n3 7 AND a.n4 = b.n4 8 AND a.n4 = 0 but I found out that also prints (1,1,2) since in the example (1,1,2,0) happens twice from IDs 5 and 6. Any suggestions would be really appreciated.

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  • How costly performance-wise are these actions in iPhone objective-C?

    - by Alex Gosselin
    This is really a few questions in one, I'm wondering what the performance cost is for these things, as I haven't really been following a best practice of any sort for these. The answers may also be useful to other readers, if somebody knows these. (1) If I need the core data managed object context, is it bad to use #import "myAppDelegate.h" //farther down in the code: NSManagedObjectContext *context = [(myAppDelegate.h*)[[UIApplication sharedApplication] delegate] managedObjectContext]; as opposed to leaving the warning you get if you don't cast the delegate? (2) What is the cheapest way to hard-code a string? I have been using return @"myString"; on occasion in some functions where I need to pass it to a variety of places, is it better to do it this way: static NSString *str = @"myString"; return str; (3) How costly is it to subclass an object i wrote vs. making a new one, in general? (4) When I am using core data and navigating through a hierarchy of some sort, is it necessary to turn things back into faults somehow after I read some info from them? or is this done automatically? Thanks for any help.

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  • (iphone) can i give different intervals between images when animating?

    - by Eugene
    Hi, I'm animating several image as follows. UIImageView* animationView = [[UIImageView alloc] initWithFrame: self.animationViewContainer.bounds]; animationView.animationImages = animationArray; animationView.animationDuration = 0.5; animationView.animationRepeatCount = 5; [animationView startAnimating]; What I'd like to do is, controlling duration between animationImages. For instance, show image1 for 0.3 sec image2 for 0.5 sec.. There must be some way to do this, but hard to find an answer. I've asked the same question here before, but wording of the question wasn't so clear. Thank you

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  • C++ pointer to functions, Beginner Question...

    - by BobAlmond
    Hi all, I want to ask about pointer in C++ I have some simple code: int add(int a, int b){ return a+b; } int runner(int x,int y, int (*functocall)(int, int)){ return (*functocall)(x,y); } now, suppose I call those functions using this way : cout<<runner(2,5,&add); or maybe cout<<runner(2,5,add); is there any difference? because when I tried, the result is the same and with no error. Thanks a lot

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  • C++ beginner question regarding chars

    - by Samwhoo
    I'm just messing around with some C++ at the moment trying to make a simple tic-tac-toe game and I'm running into a bit of a problem. This is my code: #include <iostream> using namespace std; class Square { public: char getState() const; void setState(char); Square(); ~Square(); private: char * pState; }; class Board { public: Board(); ~Board(); void printBoard() const; Square getSquare(short x, short y) const; private: Square board[3][3]; }; int main() { Board board; board.getSquare(1,2).setState('1'); board.printBoard(); return 0; } Square::Square() { pState = new char; *pState = ' '; } Square::~Square() { delete pState; } char Square::getState() const { return *pState; } void Square::setState(char set) { *pState = set; } Board::~Board() { } Board::Board() { } void Board::printBoard() const { for (int x = 0; x < 3; x++) { cout << "|"; for (int y = 0; y < 3; y++) { cout << board[x][y].getState(); } cout << "|" << endl; } } Square Board::getSquare(short x, short y) const { return board[x][y]; } Forgive me if there are blatantly obvious problems with it or it's stupidly written, this is my first program in C++ :p However, the problem is that when I try and set the square 1,2 to the char '1', it doesn't print out as a 1, it prints out as some strange character I didn't recognise. Can anyone tell me why? :) Thanks in advance.

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  • Opening a streaming connection to an HTTP server on iPhone/Cocoa environment?

    - by Paul
    I've been using NSURLConnection to do a HTTP post to establish the connection. I've also implemented the didReceiveData delegagate to process incoming bytes as they become available. As incoming data comes in via didReceiveData, I add the NSData to a data buffer and try parsing the bytesteam if enough data has come in to complete a message segment. I'm having a hard time managing the data buffer (NSMutableData object) to remove bytes that have been parsed to structs. Was curious if there's an easier way. Thanks

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  • how to fetch data from Plist in Label

    - by SameSung Vs Iphone
    I have a RegistrationController screen to store email-id ,password,DOB,Height,Weight and logininController screen to match email-id and password to log-in purpose. Now In some third screen I have to fetch only the Height,Weight from the plist of the logged-in user to display it on the label.now if I Store the values of email-id and password in from LoginViewController in string and call it in the new screen to match if matches then gives Height,Weight ..if it corrects then how to fetch Height,Weight from the plist of the same one. how can i fetch from the stored plist in a string... the code which i used to match in LoginController -(NSArray*)readFromPlist { NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [documentPaths objectAtIndex:0]; NSString *documentPlistPath = [documentsDirectory stringByAppendingPathComponent:@"XYZ.plist"]; NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:documentPlistPath]; NSArray *valueArray = [dict objectForKey:@"title"]; return valueArray; } - (void)authenticateCredentials { NSMutableArray *plistArray = [NSMutableArray arrayWithArray:[self readFromPlist]]; for (int i = 0; i< [plistArray count]; i++) { id object = [plistArray objectAtIndex:i]; if ([object isKindOfClass:[NSDictionary class]]) { NSDictionary *objDict = (NSDictionary *)object; if ([[objDict objectForKey:@"pass"] isEqualToString:emailTextFeild.text] && [[objDict objectForKey:@"title"] isEqualToString:passwordTextFeild.text]) { NSLog(@"Correct credentials"); return; } NSLog(@"INCorrect credentials"); } else { NSLog(@"Error! Not a dictionary"); } } }

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  • Strategy for animation a lot of LED's - thread?, UIView animations? NSOperation? (iPhone)

    - by RickiG
    Hi I have to do some different views containing 72 LED lights. I built an LED Class so I can loop through the LED's and set them to different colors (Green, Red, Orange, Blue None etc.). The LED then loads the appropriate .png. This works fine, I loop over the LED's and set them. Now I know that at some time they will need to not just turn on/off change color, but will have to turn on with a small delay. Like an equalizer. I have a 5-10 views containing the 72 LED's and I would like to achieve the above with the minimum amount of memory/CPU strain. for(LED *l in self.ledArray) { [l display:Green]; } I simply loop as shown above and inside the LED is a switch case that does the correct logic. If this were actual LED's and a microController I would use sleep(100) or similar in the loop, but I would really like to avoid stuff like that for obvious reasons. I was thinking that doing a performOnThread withDelay would really be consuming, so would UIView animation changing the alpha and NSOperation would also be a lot of lifting for a small feature. Is there a both efficient and clever way to go around this? Thanks for any inspiration given:)

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  • beginner's question about CSS

    - by Nitesh Panchal
    Hello, I am creating a website and i want to allow personalization to individual users upto some extent like changing font family, background color etc. The problem with this is that, my default css file that i load has already default classes for everything. Now when i fetch the background color from my database, then if there is null value for background color then default css class of mystylesheet.css should be loaded and if the value is not null, then i want to override this with my default css. How is it possible? Thanks in advance :)

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  • How do I load a Direct X .x 3D model in iPhone SDK?

    - by Alex
    I have been searching the internet for the last few days trying to figure this out. My goal is to draw a textured and animated .x file exported from a 3D program. I found a tutorial of how to load and draw a .obj file, which I understand, but the tutorial doesn't say how to texture it, and .obj doesn't support animation. The .x file structure is human readable just like .obj, but I have no clue how to texture it, and I might be able to figure out how to animate it, but I would prefer to be instructed on that. Any help would be GREATLY appreciated.

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