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  • How important is managing memory in Objective-C?

    - by Alex Mcp
    Background: I'm (jumping on the bandwagon and) starting learning about iPhone/iPad development and Objective-C. I have a great background in web development and most of my programming is done in javascript (no libraries), Ruby, and PHP. Question: I'm learning about allocating and releasing memory in Objective-C, and I see it as quite a tricky task to layer on top of actually getting the farking thing to run. I'm trying to get a sense of applications that are out there and what will happen with a poorly memory-managed program. A) Are apps usually released with no memory leaks? Is this a feasible goal, or do people more realistically just excise the worst offenders and that's ok? B) If I make an NSString for a title of a view, let's say, and forget to deallocate it it, does this really only become a problem if I recreate that string repeatedly? I imagine what I'm doing is creating an overhead of the memory needed to store that string, so it's probably quite piddling (a few bytes?) However if I have a rapidly looping cycle in a game that 'leaks' an int every cycle or something, that would overflow the app quite quickly. Are these assumptions correct? Sorry if this isn't up the community-wiki alley, I'm just trying to get a handle on how to think about memory and how careful I'll need to be. Any anecdotes or App Store-submitted app experiences would be awesome to hear as well.

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  • Fuzzy Date algorithm in Objective-C

    - by Brock Woolf
    I would like to write a fuzzy date method for calculating dates in Objective-C for iPhone. There is a popular explanation here: http://stackoverflow.com/questions/11/how-do-i-calculate-relative-time However it contains missing arguments. How could this be used in Objective-C?. Thanks. const int SECOND = 1; const int MINUTE = 60 * SECOND; const int HOUR = 60 * MINUTE; const int DAY = 24 * HOUR; const int MONTH = 30 * DAY; if (delta < 1 * MINUTE) { return ts.Seconds == 1 ? "one second ago" : ts.Seconds + " seconds ago"; } if (delta < 2 * MINUTE) { return "a minute ago"; } if (delta < 45 * MINUTE) { return ts.Minutes + " minutes ago"; } if (delta < 90 * MINUTE) { return "an hour ago"; } if (delta < 24 * HOUR) { return ts.Hours + " hours ago"; } if (delta < 48 * HOUR) { return "yesterday"; } if (delta < 30 * DAY) { return ts.Days + " days ago"; } if (delta < 12 * MONTH) { int months = Convert.ToInt32(Math.Floor((double)ts.Days / 30)); return months <= 1 ? "one month ago" : months + " months ago"; } else { int years = Convert.ToInt32(Math.Floor((double)ts.Days / 365)); return years <= 1 ? "one year ago" : years + " years ago"; }

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  • Objective-C memory model

    - by TofuBeer
    I am attempting to wrap my head around one part of the Objective-C memory model (specifically on the iPhone, so no GC). My background is C/C++/Java, and I am having an issue with the following bit of code (also wondering if I am doing this in an "Objective-C way" or not): - (NSSet *) retrieve { NSMutableSet *set; set = [NSMutableSet new]; // would normally fill the set in here with some data return ([set autorelease]); } - (void) test { NSSet *setA; NSSet *setB; setA = [self retrieve]; setB = [[self retrieve] retain]; [setA release]; [setB release]; } start EDIT Based on comments below, the updated retrieve method: - (NSSet *) retrieve { NSMutableSet *set; set = [[[NSMutableSet alloc] initWithCapacity:100] autorelease]; // would normally fill the set in here with some data return (set); } end EDIT The above code gives a warning for [setA release] "Incorrect decrement of the reference count of an object is not owned at this point by the caller". I though that the "new" set the reference count to 1. Then the "retain" call would add 1, and the "release" call would drop it by 1. Given that wouldn't setA have a reference count of 0 at the end and setB have a reference count of 1 at the end? From what I have figured out by trial and error, setB is correct, and there is no memory leak, but I'd like to understand why that is the case (what is wrong with my understanding of "new", "autorelease", "retain", and "release").

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  • C++ stack in Objective-C++

    - by helixed
    I'd like to use a C++ stack type in Objective-C, but I'm running into some issues. Here's a sample of what I would like to do: #import <stack> #import <UIKit/UIKit.h> @interface A : NSObject { stack<SEL> selectorStack; } @end Unfortunately, this doesn't compile. After messing around with the code for a while and trying different things, I can't seem to find a way to accomplish this. Can somebody tell me the best way to use a C++ stack within an Objective-C object or if it's even possible? Thanks. UPDATE: Well, KennyTM's answer worked on my example file, but for some reason when I tried to rename the class it quit working. Here's the code I have right now: #import <stack> #import <UIKit/UIKit.h> @interface MenuLayer : NSObject { std::stack<SEL> selectorStack; } @end The compiler spits out the following errors: stack: No such file or directory expected specifier-qualifier-list before 'std'

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  • Want to learn Objective-C but syntax is very confusing

    - by Sahat
    Coming from Java background I am guessing this is expected. I would really love to learn Objective-C and start developing Mac apps, but the syntax is just killing me. For example: -(void) setNumerator: (int) n { numerator = n; } What is that dash for and why is followed by void in parenthesis? I've never seen void in parenthesis in C/C++, Java or C#. Why don't we have a semicolon after (int) n? But we do have it here: -(void) setNumerator: (int) n; And what's with this alloc, init, release process? myFraction = [Fraction alloc]; myFraction = [myFraction init]; [myFraction release]; And why is it [myFraction release]; and not myFraction = [myFraction release]; ? And lastly what's with the @ signs and what's this implementation equivalent in Java? @implementation Fraction @end I am currently reading Programming in Objective C 2.0 and it's just so frustrating learning this new syntax for someone in Java background.

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  • iPhone Objective-C service handlers

    - by Xavi Colomer
    Hello community! I am a as3 developer, I am used to use handlers everytime I launch an event and I am wondering which is the best way / practice to do that in Objective C. Let's say I want to call a diferent services from my backend. In as3 would be something like this to listent to the finish event: service.addEventListener( Event.COMPLETE, handler_serviceDidFinished ) service2.addEventListener( Event.COMPLETE, handler_serviceDidFinished2 ) But how can I do the same in Objective C? The problem is I already created the protocols and delegates, but how can I separate each response from the server? For example: -(void)callService:( NSString * )methodName withParameters:(NSMutableDictionary *) parameters { ... if (self.delegate != NULL && [self.delegate respondsToSelector:@selector(serviceDidFinishSuccessfully:)]) { [delegate serviceDidFinishSuccessfully:data]; } } Well I'm trying to create a generic delegate here, so how can I separate each response for every service? My first idea is that maybe I should return the name of the service method in the delegate call to identify each service. Maybe I should create a UID for each service and pass it the same way... Any idea?

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  • Learning Objective-C: Need advice on populating NSMutableDictionary

    - by Zigrivers
    I am teaching myself Objective-C utilizing a number of resources, one of which is the Stanford iPhone Dev class available via iTunes U (past 2010 class). One of the home work assignments asked that I populate a mutable dictionary with a predefined list of keys and values (URLs). I was able to put the code together, but as I look at it, I keep thinking there is probably a much better way for me to approach what I'm trying to do: Populate a NSMutableDictionary with the predefined keys and values Enumerate through the keys of the dictionary and check each key to see if it starts with "Stanford" If it meets the criteria, log both the key and the value I would really appreciate any feedback on how I might improve on what I've put together. I'm the very definition of a beginner, but I'm really enjoying the challenge of learning Objective-C. void bookmarkDictionary () { NSMutableDictionary* bookmarks = [NSMutableDictionary dictionary]; NSString* one = @"Stanford University", *two = @"Apple", *three = @"CS193P", *four = @"Stanford on iTunes U", *five = @"Stanford Mall"; NSString* urlOne = @"http://www.stanford.edu", *urlTwo = @"http://www.apple.com", *urlThree = @"http://cs193p.stanford.edu", *urlFour = @"http://itunes.stanford.edu", *urlFive = @"http://stanfordshop.com"; NSURL* oneURL = [NSURL URLWithString:urlOne]; NSURL* twoURL = [NSURL URLWithString:urlTwo]; NSURL* threeURL = [NSURL URLWithString:urlThree]; NSURL* fourURL = [NSURL URLWithString:urlFour]; NSURL* fiveURL = [NSURL URLWithString:urlFive]; [bookmarks setObject:oneURL forKey:one]; [bookmarks setObject:twoURL forKey:two]; [bookmarks setObject:threeURL forKey:three]; [bookmarks setObject:fourURL forKey:four]; [bookmarks setObject:fiveURL forKey:five]; NSString* akey; NSString* testString = @"Stanford"; for (akey in bookmarks) { if ([akey hasPrefix:testString]) { NSLog(@"Key: %@ URL: %@", akey, [bookmarks objectForKey:akey]); } } } Thanks for your help!

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  • Objective-C Simple Inheritance and OO Principles

    - by bleeckerj
    I have a subclass SubClass that inherits from baseclass BaseClass. BaseClass has an initializer, like so: -(id)init { self = [super init]; if(self) { [self commonInit]; } return self; } -(void)commonInit { self.goodStuff = [[NSMutableArray alloc]init]; } SubClass does its initializer, like so: -(id)init { self = [super init]; if(self) { [self commonInit]; } return self; } -(void)commonInit { self.extraGoodStuff = [[NSMutableArray alloc]init]; } Now, I've *never taken a proper Objective-C course, but I'm a programmer more from the Electrical Engineering side, so I make do. I've developed server-side applications mostly in Java though, so I may be seeing the OO world through Java principles. When SubClass is initialized, it calls the BaseClass init and my expectation would be — because inheritance to me implies that characteristics of a BaseClass pass through to SubClass — that the commonInit method in BaseClass would be called during BaseClass init. It is not. I can *sorta understand maybe-possibly-stretch-my-imagination why it wouldn't be. But, then — why wouldn't it be based on the principles of OOP? What does "self" represent if not the instance of the class of the running code? Okay, so — I'm not going to argue that what a well-developed edition of Objective-C is doing is wrong. So, then — what is the pattern I should be using in this case? I want SubClass to have two main bits — the goodStuff that BaseClass has as well as the extraGoodStuff that it deserves as well. Clearly, I've been using the wrong pattern in this type of situation. Am I meant to expose commonInit (which makes me wonder about encapsulation principles — why expose something that, in the Java world at least, would be considered "protected" and something that should only ever be called once for each instance)? I've run into a similar problem in the recent past and tried to muddle through it, but now — I'm really wondering if I've got my principles and concepts all straight in my head. Little help, please.

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  • Objective-C respondsToSelector question.

    - by Holli
    From what I have learned so far: In Objective-C you can send any message to any object. If the object does implement the right method it will be executed otherwise nothing will happen. This is because before the message is send Objective-C will perform respondsToSelector. I hope I am right so far. I did a little program for testing where an action is invoked every time a slider is moved. Also for testing I set the sender to NSButton but in fact it is an NSSlider. Now I asked the object if it will respond to setAlternateTitle. While a NSButton will do and NSSlider will not. If I run the code and do respondsToSelector myself it will tell me the object will not respond to that selector. If I test something else like intValue, it will respond. So my code is fine so far. - (IBAction)sliderDidMove:(id)sender { NSButton *slider = sender; BOOL responds = [slider respondsToSelector:@selector(setAlternateTitle)]; if(responds == YES) { NSLog(@"YES"); } else { NSLog(@"NO"); } [slider setAlternateTitle:@"Hello World"]; } But when I actually send the setAlternateTitle message the program will crash and I am not exactly sure why. Shouldn't it do a respondsToSelector before sending the message?

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  • Good Learning Method for Objective-C?

    - by Josh Kahane
    Hi I know this must be asked a millions times and can't be easy to answer as there is o definitive method, but any help would be appreciated, thanks. I have been playing around with all sorts of things in Xcode and with Objective-C, however I can't seem to find a good way of learning things in an efficient way. I have bought the book 'Programming in Objective-C 2.0' and its great but just lays down the basics it seems. I want to learn in the 2D game development direction, then of course 3D after nailing that, if thats the right thing to do? I am 17 currently in year 13, last year of school/A Levels and am almost definitely taking a gap year. Any good, well known reputable courses online or offline (real world)? This is my first programming language, and I am absolutely serious about learning this. One last question, is when learning things online, I have in the past started building a feature and learning a certain aspect in programming only to find out after adding more its slows down the app or its to inefficient. Is the key to use a certain method in a certain situation (being os many ways to do the same thing) or use any of those methods and refine it in your app to make it run smoothly? Sorry, its hard for me to know when I have little experience, thus far. Sorry for rambling on! I would appreciate any help, thank you!

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  • pass objective c object and primitive type into a void *

    - by user674669
    I want to pass 2 variables: UIImage * img int i into another method that only takes a (void *) I tried making a C struct containing both img and i struct MyStruct { UIImage *img; int i; } but xcode gives me an error saying "ARC forbids Objective-C objects in structs or unions" The next thing I tried is to write an objective-c class MyStruct2 containing img and i, alloc-initing an instance of it and typecasting it as (__bridge void*) before passing it to the method. Seems little involved for my use case. Seems like there should be a better way. What's the simplest way to achieve this? Thank you. Edit based on comments: I have to use void * as it is required by the UIView API. I created a selector as mentioned by UIVIew API + (void)setAnimationDidStopSelector:(SEL)selector Please see documentation for setAnimationDidStopSelector at http://developer.apple.com/library/ios/#documentation/uikit/reference/UIView_Class/UIView/UIView.html . It says ... The selector should be of the form: - (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context I want to pass both img and i into the (void *)context argument.

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  • Why do properties require explicit typing during compilation?

    - by ctpenrose
    Compilation using property syntax requires the type of the receiver to be known at compile time. I may not understand something, but this seems like a broken or incomplete compiler implementation considering that Objective-C is a dynamic language. The property "comment" is defined with: @property (nonatomic, retain) NSString *comment; and synthesized with: @synthesize comment; "document" is an instance of one of several classes which conform to: @protocol DocumentComment <NSObject> @property (nonatomic, retain) NSString *comment; @end and is simply declared as: id document; When using the following property syntax: stringObject = document.comment; the following error is generated by gcc: error: request for member 'comment' in something not a structure or union However, the following equivalent receiver-method syntax, compiles without warning or error and works fine, as expected, at run-time: stringObject = [document comment]; I don't understand why properties require the type of the receiver to be known at compile time. Is there something I am missing? I simply use the latter syntax to avoid the error in situations where the receiving object has a dynamic type. Properties seem half-baked.

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  • improve Collision detection memory usage (blocks with bullets)

    - by Eddy
    i am making a action platform 2D game, something like Megaman. I am using XNA to make it. already made player phisics,collisions, bullets, enemies and AIs, map editor, scorolling X Y camera (about 75% of game is finished ). as i progressed i noticed that my game would be more interesting to play if bullets would be destroyed on collision with regular(stationary ) map blocks, only problem is that if i use my collision detection (each bullet with each block) sometimes it begins to lag(btw if my bullet exits the screen player can see it is removed from bullet list) So how to improve my collision detection so that memory usage would be so high? :) ( on a map 300x300 blocks for example don't think that bigger map should be made); int block = 0; int bulet= 0; bool destroy_bullet = false; while (bulet < bullets.Count) { while (block < blocks.Count) { if (bullets[bulet].P_Bul_rec.Intersects( blocks[block].rect)) {//bullets and block are Lists that holds objects of bullet and block classes //P_Bul_rec just bullet rectangle destroy_bullet = true; } block++; } if (destroy_bullet) { bullets.RemoveAt(bulet); destroy_bullet = false; } else { bulet++; } block = 0; }

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  • How much overhead does a msg_send call incur?

    - by pxl
    I'm attempting to piece together and run a list of tasks put together by a user. These task lists can be hundreds or thousand of items long. From what I know, the easiest and most obvious way would be to build an array and then iterate through them: NSArray *arrayOfTasks = .... init and fill with thousands of tasks for (id *eachTask in arrayOfTasks) { if ( eachTask && [eachTask respondsToSelector:@selector(execute)] ) [eachTask execute]; } For a desktop, this may be no problem, but for an iphone or ipad, this may be a problem. Is this a good way to go about it, or is there a faster way to accomplish the same thing? The reason why I'm asking about how much overhead a msg_send occurs is that I could also do a straight C implementation as well. For example, I could put together a linked list and use a block to handle the next task. Will I gain anything from that or is it really more trouble than its worth?

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  • Singleton Issues in iOS http client

    - by Andrew Lauer Barinov
    I implemented an HTTP client is iOS that is meant to be a singleton. It is a subclass of AFNetworking's excellent AFHTTPClient My access method is pretty standard: + (LBHTTPClient*) sharedHTTPClient { static dispatch_once_t once = 0; static LBHTTPClient *sharedHTTPClient = nil; dispatch_once(&once, ^{ sharedHTTPClient = [[LBHTTPClient alloc] initHTTPClient]; }); return sharedHTTPClient; } // my init method - (id) initHTTPClient { self = [super initWithBaseURL:[NSURL URLWithString:kBaseURL]]; if (self) { // Sub class specific initializations } return self; } Super's init method is very long, and can be found here However the problem I experience is when the dispatch_once queue is run, the app locks and become unresponsive. When I step through code, I notice that it locks on dispatch_once and then remains frozen. Is this something to do with the main thread locking down? How come it stays locked like that? Also, none of the HTTP client methods fire. Stepping through the code some more, I find this line in dispatch/once.h is where the app locks down: DISPATCH_INLINE DISPATCH_ALWAYS_INLINE DISPATCH_NONNULL_ALL DISPATCH_NOTHROW void _dispatch_once(dispatch_once_t *predicate, dispatch_block_t block) { if (DISPATCH_EXPECT(*predicate, ~0l) != ~0l) { dispatch_once(predicate, block); // App locks here } }

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  • Objects not loading on second request in Restkit

    - by Holger Edward Wardlow Sindbæk
    I'm sending off 2 requests simultaneously with Restkit and I receive a response back from both of them, but only one of the requests receives any objects. If I send them off one by one, then my objectloader receives all objects. First request: self.firstObjectManager = [RKObjectManager sharedManager]; [self.firstObjectManager loadObjectsAtResourcePath:[NSString stringWithFormat: @"/%@.json", subUrl] usingBlock:^(RKObjectLoader *loader){ [loader.mappingProvider setObjectMapping:designArrayMapping forKeyPath:@""]; loader.userData = @"design"; loader.delegate = self; [loader sendAsynchronously]; }]; Second request: self.secondObjectManager = [RKObjectManager sharedManager]; [self.secondObjectManager loadObjectsAtResourcePath:[NSString stringWithFormat: @"/%@.json", subUrl] usingBlock:^(RKObjectLoader *loader){ [loader.mappingProvider setObjectMapping:designerMapping forKeyPath:@""]; loader.userData = @"designer"; loader.delegate = self; [loader sendAsynchronously]; }]; My objecloader: -(void)objectLoader:(RKObjectLoader *)objectLoader didLoadObjects:(NSArray *)objects { //NSLog(@"This happened: %@", objectLoader.userData); if (objectLoader.userData == @"design") { NSLog(@"Design happened: %i", objects.count); }else if(objectLoader.userData == @"designer"){ NSLog(@"designer: %@", [objects objectAtIndex:0]); } } My response: 2012-11-18 14:36:19.607 RestKitTest5[14220:c07] Started loading of request: designer 2012-11-18 14:36:22.575 RestKitTest5[14220:c07] I restkit.network:RKRequest.m:680:-[RKRequest updateInternalCacheDate] Updating cache date for request <RKObjectLoader: 0x95c3160> to 2012-11-18 19:36:22 +0000 2012-11-18 14:36:22.576 RestKitTest5[14220:c07] response code: 200 2012-11-18 14:36:22.584 RestKitTest5[14220:c07] Design happened: 0 2012-11-18 14:36:22.603 RestKitTest5[14220:c07] I restkit.network:RKRequest.m:680:-[RKRequest updateInternalCacheDate] Updating cache date for request <RKObjectLoader: 0xa589b50> to 2012-11-18 19:36:22 +0000 2012-11-18 14:36:22.605 RestKitTest5[14220:c07] response code: 200 2012-11-18 14:36:22.606 RestKitTest5[14220:c07] designer: <DesignerData: 0xa269fc0> Update: Setting my base url RKURL *baseURL = [RKURL URLWithBaseURLString:@"http://iphone.meer.li"]; [RKObjectManager setSharedManager:[RKObjectManager managerWithBaseURL:baseURL]]; Solution Problem was that I used the shared manager for both object managers, so I ended up doing: RKURL *baseURL = [RKURL URLWithBaseURLString:@"http://iphone.meer.li"]; RKObjectManager *myObjectManager = [[RKObjectManager alloc] initWithBaseURL:baseURL]; self.firstObjectManager = myObjectManager; and: RKURL *baseURL = [RKURL URLWithBaseURLString:@"http://iphone.meer.li"]; RKObjectManager *myObjectManager = [[RKObjectManager alloc] initWithBaseURL:baseURL]; self.secondObjectManager = myObjectManager;

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  • Completion block not being called. How to check validity?

    - by HCHogan
    I have this method which takes a block, but that block isn't always called. See the method: - (void)updateWithCompletion:(void (^)(void))completion { [MYObject myMethodWithCompletion:^(NSArray *array, NSError *error) { if (error) { NSLog(@"%s, ERROR not nil", __FUNCTION__); completion(); return; } NSLog(@"%s, calling completion %d", __FUNCTION__, &completion); completion(); NSLog(@"%s, finished completion", __FUNCTION__); }]; } I have some more NSLogs inside completion. Sometimes this program counter just blows right past the call to completion() in the code above. I don't see why this would be as the calling code always passes a literal block of code as input. If you're curious of the output of the line containing the addressof operator, it's always something different, but never 0 or nil. What would cause completion not to be executed?

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  • Objective-C library recommendation for AES-256 in CTR mode

    - by lpfavreau
    Hello, I'm looking for recommendations on an Objective-C library for AES-256 encryption in CTR mode. I have a database full of data encrypted with another library using CTR and seems the included CCCrypt only supports ECB or CBC with PKCS#7. Any idea on the best portable library I should use? I'm not looking to port the original implementation as I don't have the required knowledge in cryptography and hence, that's-a-bad-idea (tm). Thanks!

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  • IPhone/Objective-c RSA encryption

    - by Paul
    Hello, I have been google-ing and researching for an answer on how to do a simple RSA encryption using objective-c on an iphone. The main problem i have is that i have been supplied the Exponent and Modulus as an NSData object and i need to then convert them to a SecKeyRef object in order to perform the RSA encryption. Does anyone have any idea how to do that or have any useful hints? Many thanks!

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  • HTML character decoding in Objective-C / Cocoa Touch

    - by skidding
    First of all, I found this: http://stackoverflow.com/questions/659602/objective-c-html-escape-unescape, but it doesn't work for me. My encoded characters (come from a RSS feed, btw) look like this: &#038; I searched all over the net and found related discussions, but no fix for my particular encoding, I think they are called hexadecimal characters. Thanks.

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  • Sorting a multidimensional array in objective-c

    - by Zen_silence
    Hello, I'm trying to sort a multidimensional array in objective-c i know that i can sort a single dimensional array using the line of code below: NSArray *sortedArray = [someArray sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)]; I can't seem to figure out how to sort a 2D array like the one below: ( ("SOME_URL", "SOME_STORY_TITLE", "SOME_CATEGORY"), ("SOME_URL", "SOME_STORY_TITLE", "SOME_CATEGORY"), ("SOME_URL", "SOME_STORY_TITLE", "SOME_CATEGORY") ); If someone could provide me code that would sort the array by SOME_CATEGORY it would be of great help to me. Thanks, Zen_Silence

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  • Objective-C Out of scope problem

    - by davbryn
    Hi, I'm having a few problems with some Objective-C and would appreciate some pointers. So I have a class MapFileGroup which has the following simple interface (There are other member variables but they aren't important): @interface MapFileGroup : NSObject { NSMutableArray *mapArray; } @property (nonatomic, retain) NSMutableArray *mapArray; mapArray is @synthesize'd in the .m file. It has an init method: -(MapFileGroup*) init { self = [super init]; if (self) { mapArray = [NSMutableArray arrayWithCapacity: 10]; } return self; } It also has a method for adding a custom object to the array: -(BOOL) addMapFile:(MapFile*) mapfile { if (mapfile == nil) return NO; mapArray addObject:mapfile]; return YES; } The problem I get comes when I want to use this class - obviously due to a misunderstanding of memory management on my part. In my view controller I declare as follows: (in the @interface): MapFileGroup *fullGroupOfMaps; With @property @property (nonatomic, retain) MapFileGroup *fullGroupOfMaps; Then in the .m file I have a function called loadMapData that does the following: MapFileGroup *mapContainer = [[MapFileGroup alloc] init]; // create a predicate that we can use to filter an array // for all strings ending in .png (case insensitive) NSPredicate *caseInsensitivePNGFiles = [NSPredicate predicateWithFormat:@"SELF endswith[c] '.png'"]; mapNames = [unfilteredArray filteredArrayUsingPredicate:caseInsensitivePNGFiles]; [mapNames retain]; NSEnumerator * enumerator = [mapNames objectEnumerator]; NSString * currentFileName; NSString *nameOfMap; MapFile *mapfile; while(currentFileName = [enumerator nextObject]) { nameOfMap = [currentFileName substringToIndex:[currentFileName length]-4]; //strip the extension mapfile = [[MapFile alloc] initWithName:nameOfMap]; [mapfile retain]; // add to array [fullGroupOfMaps addMapFile:mapfile]; } This seems to work ok (Though I can tell I've not got the memory management working properly, I'm still learning Objective-C); however, I have an (IBAction) that interacts with the fullGroupOfMaps later. It calls a method within fullGroupOfMaps, but if I step into the class from that line while debugging, all fullGroupOfMaps's objects are now out of scope and I get a crash. So apologies for the long question and big amount of code, but I guess my main question it: How should I handle a class with an NSMutableArray as an instance variable? What is the proper way of creating objects to be added to the class so that they don't get freed before I'm done with them? Many thanks

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  • WWW::Mechanize for Objective C / iPhone?

    - by dan
    Hi, I want to port a python app that uses mechanize for the iPhone. This app needs to login to a webpage and using the site cookie to go to other pages on that site to get some data. With my python app I was using mechanize for automatic cookie management. Is there something similar for Objective C that is portable to the iPhone? Thanks for any help.

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