Should I check if a file exists at a given path when trying to read the data into an NSData object? Right now I'm not doing at the moment but my code works since my array that is supposed to get populated with data from the file will be set to nil and I can later in my application check if that array is nil. But I'm thinking that the code is perhaps "ugly" and would work better if i did a check (like the one in the commented code).
NSData *codedData = [[NSData alloc] initWithContentsOfFile:[CareersParser dataFilePath]];
/*
if (codedData != nil) {
//do the below (not commented out code)
} else {
//file doesn't exist at the given path
[codedData release];
return nil;
}
*/
NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:codedData];
NSArray *careers = [unarchiver decodeObjectForKey:kDataKey];
[unarchiver finishDecoding];
NSMutableArray *ids = [[NSMutableArray alloc] init];
for (Career *career in careers) {
[ids addObject:[career id]];
}
// Sort the array in an orderly fashion
NSArray *sortedIds = [ids sortedArrayUsingSelector:#selector(caseInsensitiveCompare:)];
// Release allocated memory
[ids release];
[unarchiver release];
[codedData release];
return sortedIds;
That seems sensible to me I would reverse the if statement to do away with the else clause.
if (nil == codedDate) {
[codedData release];
return nil;
}
... Do the rest of your code
Apple suggests here that you should attempt to perform an operation such as loading data like you have suggested. As long as you don't try to do [[NSManager defaultManager] fileExistsAtPath:path] you won't be introducing race conditions.
You don't, and this could introduce a race, so it will be more "ugly". Just check if codedData if nil in case of reading failure.
Related
Ok, im a bit lost with this one, i am currently trying to run a background core data operation using a second ManagedObjectContext with its type set to NSPrivateQueueConcurrencyType and failing miserably with the above error.
I have a custom subclass of NSOperation, which is being passed an NSArray of strings, and the PersistentStoreCoordinator from the main thread, it then creates its own ManagedObjectContext, runs a query and performs and operation.
Here is the code from the class:
//
// ProcessProfanity.m
// Hashtag Live Desktop
//
// Created by Gareth Jeanne on 24/03/2014.
// Copyright (c) 2014 Gareth Jeanne. All rights reserved.
//
#import "ProcessProfanity.h"
#import "Tweet.h"
static const int ImportBatchSize = 250;
#interface ProcessProfanity ()
#property (nonatomic, copy) NSArray* badWords;
#property (nonatomic, strong) NSManagedObjectContext* backgroundContext;
#property (nonatomic, strong) NSPersistentStoreCoordinator* persistentStoreCoordinator;
#end
#implementation ProcessProfanity
{
}
- (id)initWithStore:(NSPersistentStoreCoordinator*)store badWords:(NSArray*)words
{
self = [super init];
if(self) {
self.persistentStoreCoordinator = store;
self.badWords = words;
}
return self;
}
- (void)main
{
_backgroundContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
_backgroundContext.persistentStoreCoordinator = [self persistentStoreCoordinator];
_backgroundContext.undoManager = nil;
[_backgroundContext performBlockAndWait:^
{
[self import];
}];
}
- (void)import
{
//Create new fetch request
NSFetchRequest *request = [[NSFetchRequest alloc] init];
//Setup the Request
[request setEntity:[NSEntityDescription entityForName:#"Tweet" inManagedObjectContext:self.backgroundContext]];
NSError *error = nil;
//Create an array from the returned objects
NSArray* tweetsToProcess = [self.backgroundContext executeFetchRequest:request error:&error];
NSAssert2(tweetsToProcess != nil && error == nil, #"Error fetching events: %#\n%#", [error localizedDescription], [error userInfo]);
for (Tweet* tweetToCheck in tweetsToProcess){
__block NSString *result = nil;
[self.badWords indexOfObjectWithOptions:NSEnumerationConcurrent
passingTest:^(NSString *obj, NSUInteger idx, BOOL *stop)
{
if (tweetToCheck){
if ([tweetToCheck.text rangeOfString:obj].location != NSNotFound)
{
result = obj;
*stop = YES;
//return YES;
}
}
return NO;
}];
if (!result){
//DDLogVerbose(#"The post does not contain any of the words from the naughty list");
if(tweetToCheck){
tweetToCheck.profanity = [NSNumber numberWithBool:false];
}
}
else{
if(tweetToCheck){
//DDLogVerbose(#"The string contains '%#' from the the naughty list", result);
tweetToCheck.profanity = [NSNumber numberWithBool:true];
}
}
}
[self.backgroundContext save:NULL];
}
#end
And this is how i am calling it:
-(void)checkForProfanity{
if(!self.operationQueue){
self.operationQueue = [[NSOperationQueue alloc] init];
}
NSArray* termsToPass = [self.filterTerms copy];
ProcessProfanity* operation = [[ProcessProfanity alloc] initWithStore:self.persistentStoreCoordinator badWords:termsToPass];
[self.operationQueue addOperation:operation];
}
Edit 1
The specific line i seem to be getting the error on, or at least where Xcode is breaking is:
if ([tweetToCheck.text rangeOfString:obj].location != NSNotFound)
I have managed to narrow this down a bit, the NSArray that contains the list of terms to search the strings for is potentially quite large, possibly over a 1,000 NSStrings. If i test with an array of that size, i get the issue. However if i reduce the array to around 15 NSStrings, i do not get the error, so i don't think this is necessarily a thread related issue, i'm wondering if the array is getting released in the main thread. I have modified the code to make a deep copy, and then a __block copy as follows, but it doesn't seem to have helped.
self.badWords = [[NSArray alloc] initWithArray:words copyItems:YES];
and
for (Tweet* tweetToCheck in tweetsToProcess){
__block NSArray *array = [[NSArray alloc] initWithArray:self.badWords copyItems:YES];
__block NSString *result = nil;
[array indexOfObjectWithOptions:NSEnumerationConcurrent
In fact, at the point where Xcode breaks, if i PO array, i get an object not found message, but if i po result, i correct get an object returned that is nil.
Edit 2
So i have made the following changes, with no change:
Made the NSArray strong rather than copy:
#property (nonatomic, strong) NSArray* badWords;
And made it a copy when allocated:
self.badWords = [[NSArray alloc] initWithArray:words copyItems:YES];
And created a local copy of the NSArray with the ___block declaration inside the actual method processing the objects:
__block NSArray *array = [[NSArray alloc] initWithArray:self.badWords copyItems:YES];
Which should surely mean it sticks around for the life of the ProcessProfanity object?
Am i wrong in expecting to be able to PO the array from the breakpoint within the block?
In this instance the error message "error: NULL _cd_rawData but the object is not being turned into a fault" indicates that you are accessing a managed object outside of its context. Basically your fetch returns all the Tweets from your persistent store as faults. Once you try and access a property on the Managed Object, Core Data will fire a fault and fetch the full object from the store.
By calling the NSArray method indexOfObjectWithOptions:passingTest: with an option of NSEnumerationConcurrent you are implying that you want to perform asynchronous execution on the elements in your array. The keyword concurrent indicates that multiple threads can be used to operate on the array elements.
In your context this means that accessing a managed object inside this block might result in accessing it on a different thread from the managed object context that owns the object. So when you access tweetToCheck.text in your conditional check - if ([tweetToCheck.text rangeOfString:obj].location != NSNotFound), under the hood Core Data is fetching that managed object from the persistent store and returning it to a thread that is not part of the managed object contexts thread.
Furthermore, it is not necessary to use the method indexOfObjectWithOptions:passingTest: since you are not actually interested in the result of this operation.
It seems to me that it might be more convenient for you to use an NSSet as you are only testing to see whether or not a given tweet word exists in your profane words. Quoting the documentation for NSSet: "You can use sets as an alternative to arrays when the order of elements isn’t important and performance in testing whether an object is contained in the set is a consideration". Clearly this seems to meet your criteria.
So your init would look like:
-(id)initWithStore:(NSPersistentStoreCoordinator*)store
badWords:(NSSet*)badWords
{
self = [super init];
if(self) {
self.persistentStoreCoordinator = store;
self.badWords = [words copy];
}
return self;
}
Since you are only interested in updating tweets that have not yet been tagged for profanity you would probably only want to fetch tweets that haven't been flagged profane:
//Create new fetch request
NSFetchRequest *request = [[NSFetchRequest alloc] init];
//Setup the Request
[request setEntity:[NSEntityDescription entityForName:#"Tweet" inManagedObjectContext:self.backgroundContext]];
[request setPredicate:[NSPredicate predicateWithFormat:#"profanity = NO"]];
Now that you have an array of tweets that are not profane you could iterate through your tweets and check each word if it contains a profane word. The only thing you will need to deal with is how to separate your tweet into words (ignoring commas and exclamation marks etc). Then for each word you are going to need to strip it of diacritics and probably ignore the case. So you would end up with someone along the lines of:
if([self.badWords containsObject:badWordString]) {
currentTweet.profanity = [NSNumber numberWithBOOL:YES];
}
Remember, you can run predicates on an NSSet so you could actually perform a case and diacritic insensitive query:
NSPredicate *searchPredicate = [NSPredicate predicateWithFormat:#"SELF = %#[cd]",wordToCheck];
BOOL foundABadWord = ([[[self.badWords filteredSetUsingPredicate:searchPredicate] allObjects] count] > 0);
Another thing you might want to consider is removing duplicate words in your tweets, you don't really want to perform the same check multiple times. So depending on how you find the performance you could place each word of your tweet into an NSSet and simply run the query on the unique words in your tweet:
if([[self.badWords intersectsSet:tweetDividedIntoWordsSet]) {
//we have a profane tweet here!
}
Which implementation you choose is up to you but assuming you are only using english in your app you are definitely going to want to run a case and diacritic insensitive search.
EDIT
One final thing to note is that no matter how much you try, people will always be the best means of detecting profane or abusive language. I encourage you to read this SO's post on detecting profanity - How do you implement a good profanity filter?
Ok, so still not quite sure what was going on, but i followed Daniels advice and re-wrote the indexOfObjectWithOptions method and now it's working. For completeness, and so it hopefully helps someone else, this is what i ended up doing.
DDLogInfo(#"Processing posts to check for bad language");
for (Tweet* tweetToCheck in tweetsToProcess){
__block NSArray *array = [[NSArray alloc] initWithArray:self.badWords copyItems:YES];
__block NSString *result = nil;
NSRange tmprange;
for(NSString *string in array) {
tmprange = [tweetToCheck.text rangeOfString:[NSString stringWithFormat:#" %# ", string]];
if (tmprange.location != NSNotFound) {
result = string;
DDLogVerbose(#"Naughty Word Found: %#", string);
break;
}
}
if (!result){
//DDLogVerbose(#"The post does not contain any of the words from the naughty list");
if(tweetToCheck){
tweetToCheck.profanity = [NSNumber numberWithBool:false];
}
}
else{
if(tweetToCheck){
//DDLogVerbose(#"The string contains '%#' from the the naughty list", result);
tweetToCheck.profanity = [NSNumber numberWithBool:true];
}
}
The basic structure of my program has the user select an item from a UITableView, which corresponds to a stored text file. The file is then read into an array and a dictionary, where the array has the keys (I know I can just get the keys from the dictionary itself, this isn't my question).
The view is then changed to a UISplitView where the master view has the keys, and the detail view has the items in the dictionary attributed to that key. In this case, it's a series of "Yes/No" questions that the user selects the answer to.
My problem is this: When I click on a cell in the UITableView (first screen), it works fine, the data is read in perfectly, and so on. When I go back to the UITableView and click on the same cell again, the program crashes. Here is the read-in-from-file method:
-(NSArray *)readFromFile:(NSString *)filePath{
// NSLog(#"Path was: %#", filePath);
NSString *file = [[NSString alloc] initWithContentsOfFile:filePath];
// NSLog(#"File was: %#", file);
NSScanner *fileScanner = [[NSScanner alloc] initWithString:file];
NSString *held;
NSString *key;
NSMutableArray *detailStrings;
NSMutableArray *keys = [[NSMutableArray alloc] init];
NSMutableDictionary *details = [[NSMutableDictionary alloc] init];
/**
This is where the fun stuff happens!
**/
while(![fileScanner isAtEnd]){
//Scan the string into held
[fileScanner scanUpToString:#"\r" intoString:&held];
NSLog(#"Inside the while loop");
// If it is a character, it's one of the Key points, so we do the management necessary
if ([[NSCharacterSet lowercaseLetterCharacterSet] characterIsMember:[[held lowercaseString] characterAtIndex: 0]]){
NSArray *checkers = [[NSArray alloc] initWithArray:[held componentsSeparatedByString:#"\t"]];
NSLog(#"Word at index 2: %#", [checkers objectAtIndex:2]);
if(detailStrings != nil){
[details setObject:detailStrings forKey:key];
[detailStrings release];
}
NSLog(#"After if statement");
key = [checkers objectAtIndex:2];
[keys addObject:(NSString *) key];
detailStrings = [[NSMutableArray alloc] init];
}
else if ([[NSCharacterSet decimalDigitCharacterSet] characterIsMember:[[held lowercaseString] characterAtIndex: 0]]){
NSArray *checkers = [[NSArray alloc] initWithArray:[held componentsSeparatedByString:#"\t"]];
NSLog(#"Word at index 1: %#", [checkers objectAtIndex:1]);
[detailStrings addObject:[checkers objectAtIndex:1]];
}
}
NSLog(#"File has been read in");
[details setObject:detailStrings forKey:key];
NSArray *contents = [[NSArray alloc] initWithObjects:(NSMutableArray *) keys, (NSMutableDictionary *) details, nil];
[detailStrings release];
return contents;
}
I've determined that the program crashes inside the
if(detailStrings != nil)
statement. I figure this is because I'm missing some memory management that I am supposed to be doing, but don't have the knowledge of where it's going wrong. Any ideas as to the problem, or why it is crashing without giving me a log?
detailStrings is not initialized when you enter the while loop. When you declare NSMutableArray *detailStrings; inside a method, detailStrings is not automatically set to nil. So when you do
if ( detailStrings != nil ) { .. }
it enters the if statement and since it is not initialized, it will crash when you access detailStrings.
Another thing is that detailStrings won't be initialized if it enters the else part of the loop first. That will cause a crash too. So based on your requirement, either do
NSMutableArray *detailStrings = nil;
or initialize it before you enter the while loop.
Deepak said truth. You should initialize detailStrings with nil first.
But there is second possible issue:
I recommend also to set nil after release, because in the next loop you may test nonexistent part of memory with nil.
if(detailStrings != nil){
[details setObject:detailStrings forKey:key];
[detailStrings release];
detailStrings = nil;
}
And the third possible issue: depending from incoming data you may go to the second part of IF statement first time and try to addObject into non-initialized array.
The fourth (hope last): you have memory leak with "checkers" arrays
Here's what I'm seeing:
//read in the file
NSString *file = [[NSString alloc] initWithContentsOfFile:filePath];
//create the scanner
NSScanner *fileScanner = [[NSScanner alloc] initWithString:file];
//declare some uninitialized stuff
NSString *held;
NSString *key;
NSMutableArray *detailStrings;
//initialize some stuff
NSMutableArray *keys = [[NSMutableArray alloc] init];
NSMutableDictionary *details = [[NSMutableDictionary alloc] init];
//begin loop
while(![fileScanner isAtEnd]){
//scan up to a newline
[fileScanner scanUpToString:#"\r" intoString:&held];
//see if you scanned a lowercase string
if ([[NSCharacterSet lowercaseLetterCharacterSet] characterIsMember:[[held lowercaseString] characterAtIndex: 0]]){
//make an array
NSArray *checkers = [[NSArray alloc] initWithArray:[held componentsSeparatedByString:#"\t"]];
//do a check... against an uninitialized value
if(detailStrings != nil){
//set a potentially uninitialized value into an array with an uninitialized key
[details setObject:detailStrings forKey:key];
At this point, you're pretty much hosed.
The fix:
properly initialize your variables
run the static analyzer
read the memory management programming guide
I am not a Cocoa developer, but I have been dabbling in it to build some plugins for PhoneGap. This particular plugin method is either 1) crashing the app without saying why or 2) complaining about how I release/don't release an object. I have tried a ton of things on my end, including using an Enumerator instead of the for loop. If anyone can point me in the right direction, that would be awesome. I don't mind legwork:
- (void)getPreferences:(NSMutableArray*)arguments withDict:(NSMutableDictionary*)options {
NSUInteger argc = [arguments count];
NSString* jsCallback = nil;
if (argc > 0) {
jsCallback = [arguments objectAtIndex:0];
} else {
NSLog(#"Preferences.getPreferences: Missing 1st parameter.");
return;
}
NSDictionary *defaults = [[NSUserDefaults standardUserDefaults] dictionaryRepresentation];
NSMutableArray *keys = (NSMutableArray *) [options objectForKey:#"keys"];
NSMutableDictionary *values = [[NSMutableDictionary alloc] init];
NSUInteger ky = [keys count];
for (int i = 0; i < ky; i ++) {
#try {
[values setObject:[defaults objectForKey:[keys objectAtIndex:i]] forKey:[keys objectAtIndex:i]];
}
#catch (NSException * err) {
NSLog(#"Error %#", err);
}
}
[keys release];
NSString* jsString = [[NSString alloc] initWithFormat:#"%#(%#);", jsCallback, [values JSONRepresentation]];
[defaults release];
[values release];
[webView stringByEvaluatingJavaScriptFromString:jsString];
[jsString release];
}
Human version:
options contains a dictionary with a single key of "keys"
that key contains an array of strings (that are going to be used as keys for lookup)
I want to loop through that array and
For every value that exists in defaults for that key, copy it to values using the same key
Finally, I want to send that values back as JSON (This part was working when I just passed the entire defaults object in, so I think the JSON method is working)
From your code, it follows that you 'own' objects values and jsString (the ones you created with alloc), so you should release them and not any other.
You can read more on memory management here.
Is this the whole code? Also, what exactly error do you get?
Nikita is right, it looks as though you're overreleasing defaults, which would cause a crash later when the autorelease pool gets released. Also, if I understand what you're trying to do correctly, you could create the values dictionary with a single line of code:
NSDictionary *values = [defaultsDict dictionaryWithValuesForKeys:keys];
I am new to ObC and have a problem that i just cant fix. There may be other issues as well but the main issue is this:
Starting the app
Press button = load new view
In the new viewDidLoad i call another object/function and send a NSMutableArray
Process data and send back a NSMutableArray
App crash, see comment where. Most often when i go back and back again but sometimes the first time
As i am new to this i guess i do a lot of this wrong but could someone nice take a look at the code and give me some advice. I would assume i have problem with releasing something.
- (void)viewDidLoad {
[super viewDidLoad];
NSLog(#" ");
NSLog(#"viewDidLoad ");
NSLog(#" ");
NSLog(#">>Processing prepareGame<<");
NSMutableArray *propArray1 = [[NSMutableArray alloc] initWithObjects:#"9999", nil]; //Init with dummy numbers
AccessPropertiesFile *readMyProperties = [AccessPropertiesFile new]; //Init function call to read file
NSLog(#"Prepare to call readProperties");
propArray1 = [readMyProperties readPropertiesFile:propArray1];
NSLog(#"Back from readProperties:error after this");
/*
for (NSString *element in propArray1) {
NSLog(#"Elements in prop2Array; %#", element);
}
*/
[readMyProperties release];
[propArray1 release];
}
-(NSMutableArray *)readPropertiesFile:(NSMutableArray *)readDataArray {
NSLog(#"Processing readProperties");
// For error information
NSError *error;
//Prepare File Manager
NSString *filePath = [self dataFilePath];
NSFileManager *fileMgr;
fileMgr = [NSFileManager defaultManager];
NSArray *propertiesArray = [NSArray alloc]; //Alloc array
//Check from what module the call is coming from to ecide what to do
if ([fileMgr fileExistsAtPath: filePath] == NO) {
NSLog (#"File not found");
//File does not exists, this is the first time the game starts
//Set up default parameters
NSString *fileString =#"0\n30\n30\n10\n1\n1\n1\n2\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n1\n";
// Write default parameters to file
[fileString writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:&error];
propertiesArray = [fileString componentsSeparatedByString:#"\n"]; // each line, adjust character for line endings
}
else { //File exists
NSLog (#"File exists");
NSString *fileString = [NSString stringWithContentsOfFile:filePath
encoding:NSUTF8StringEncoding error:nil]; // reads file into memory as an NSString
propertiesArray = [fileString componentsSeparatedByString:#"\n"]; // each line, adjust character for line endings
}
//Clean readDataArray
[readDataArray removeAllObjects];
//Populate return array
for (NSString *element in propertiesArray) {
//NSLog(#"Elements in propertiesArray; %#", element);
[readDataArray addObject:element];
}
NSLog(#"readDataArray: %#", readDataArray);
[propertiesArray release];
[readDataArray autorelease];
NSLog(#"returning from readProperties");
return readDataArray;
}
#end
You are over-releasing readDataArray (known as propArray1 in the method that didn't create it). You create it and autorelease it in your second method, then you release it again at the end of your first method (where it wasn't created).
I suggest you use Analyze feature that comes with latest XCode. It is a good feature that I always use to track if I forget to release or release too much.
I also spotted that you also over-release the propertiesArray because it contains the result from [fileString componentsSeparatedByString:], which will be autorelease according to Cocoa convention.
Does this seem right, the dataFilePath is on disk and contains the right data, but the MSMutable array does not contain any objects after the initWithCoder? I am probably just missing something, but I wanted to quickly check here before moving on.
-(id)initWithCoder:(NSCoder *)decoder {
self = [super init];
if(self) {
[self setReactorCore:[decoder decodeObjectForKey:#"CORE"]];
}
return self;
}
.
-(id)init {
self = [super init];
if(self) {
if([[NSFileManager defaultManager] fileExistsAtPath:[self dataFilePath]]) {
NSMutableData *data = [[NSMutableData alloc] initWithContentsOfFile:[self dataFilePath]];
NSKeyedUnarchiver *unArchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
NSMutableArray *newCore = [[NSMutableArray alloc] initWithCoder:unArchiver];
[self setReactorCore:newCore];
[newCore release];
[data release];
[unArchiver release];
} else {
NSMutableArray *newCore = [[NSMutableArray alloc] init];
[self setReactorCore:newCore];
[newCore release];
}
}
return self;
}
EDIT_001
I think I know where I am going wrong, I am archiving NSData and then trying to initialise my NSMutable array with it. I will rework the code and post back with an update.
gary
I am confused as to why you're doing things this way. You do not normally call initWithCoder: yourself. You ask the coder for its contents and it creates the objects for you. The whole decoding part of that method should be id archivedObject = [NSKeyedUnarchiver unarchiveObjectWithFile:[self dataFilePath]], where archivedObject is presumably the array you call newCore in your code (I don't know the contents of the file, so I'm just guessing from what you wrote). In that case, you'll want to mutableCopy it, since I don't think NS*Archiver preserves mutability.
I also hope you aren't expecting your initWithCoder: method that you wrote at the top of your post to be called when this NSArray is unarchived.
"I also hope you aren't expecting your initWithCoder: method that you wrote at the top of your post to be called when this NSArray is unarchived."
is not useful. Why can't you write why it's not called? Thanks
EDIT:
In fact, if the objects in your array implement NSCoding, initWithCoding is called on each of them when you restore your array (restore here means that you call [decoder decodeObjectForKey:#"yourArray"]). I'm actually doing this in my own code. So I think what you wrote is false!