I have a problem with accessing/setting an object from/to a NSArray returned with the CFPreferencesCopyAppValue() method. My app crashes in this case whereas when I alloc/init it myself, everything works well.
CFArrayRef cfArray;
if ((cfArray = (CFArrayRef)CFPreferencesCopyAppValue(CFSTR("buttonsOrder"), appID))) {
NSArray *castedArray = [(NSArray *)cfArray retain];
NSLog(#"castedArray : %#", castedArray);
buttonsOrder = [castedArray mutableCopy];
NSLog(#"buttonsOrder : %#", buttonsOrder);
CFRelease(cfArray);
[castedArray release];
castedArray = nil;
}
else {
buttonsOrder = [[NSMutableArray alloc] init];
for (NSMutableDictionary *info in togglesInfo) {
[buttonsOrder addObject:[info objectForKey:#"buttonIdentifier"]];
}
}
PS : NSLog() shows me that CFArray is returned well and is casted to NSArray and then NSMutableArray well too.
Any idea ?
Edit :
Here is how I modofy the array :
- (void) tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
NSUInteger fromIndex = [fromIndexPath row];
NSUInteger toIndex = [toIndexPath row];
if (fromIndex == toIndex)
return;
NSString *movedButtonId = [[[buttonsOrder objectAtIndex:fromIndex] retain] autorelease];
[buttonsOrder removeObjectAtIndex:fromIndex];
[buttonsOrder insertObject:movedButtonId atIndex:toIndex];
}
If you crash while trying to add an object to a mutable array, that usually means you're attempting to add a nil object. The only place (in your code snippet above) where I see you adding anything to your mutable array is in the case where you didn't get a valid "cfArray" from CFPreferences. You should make sure "[info objectForKey:#"buttonIdentifier"]" isn't returning nil.
Check to make sure you're not throwing an exception. Or if that's not it, say what your crash really is (it'll say in the Console log of Xcode).
Related
I have a UITableView in a ViewController class. The ViewController class uses a custom dataController (specified in the AppDelegate). In the dataController class I'm fetching some JSON from the web, parsing it to an NSMutableArray, then using that data to populate the UITableView in the ViewController.
This all works great, except there is a noticeable lag when the app starts up since it takes time to get the JSON and work with it. I'd like to show an empty UITableView with an activity indicator while this data is loading. Unfortunately whenever I put the code in the dataController class into a dispatch queue, the UITableView is never populated with data (the data is loaded according to the log). All I see is a blank table.
I guess my main issue is I don't know how to set up a queue in the dataController class and then update the UI with the data in that queue but in another class.
Relevant code:
from dataController class:
- (void)initializeDefaultDataList {
NSMutableArray *dataList = [[NSMutableArray alloc] init];
self.masterDataList = dataList;
dispatch_queue_t myQueue = dispatch_queue_create("name.queue.my", NULL);
dispatch_async(myQueue, ^{
NSString *jsonString = [JSONHelper JSONpostString:#"http://webservice/getData"];
NSError *jsonError = nil;
//convert string to dictionary using NSJSONSerialization
NSDictionary *jsonResults = [NSJSONSerialization JSONObjectWithData: [jsonString dataUsingEncoding:NSUTF8StringEncoding]
options: NSJSONReadingMutableContainers
error: &jsonError];
if (jsonError) NSLog(#"[%# %#] JSON error: %#", NSStringFromClass([self class]), NSStringFromSelector(_cmd), jsonError.localizedDescription);
NSArray *dataArray = [jsonResults objectForKey:#"d"];
for (NSString *dataItem in dataArray) {
[self addDataWithItem:dataItem];
}
});
}
from AppDelegate:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
UINavigationController *navigationController = (UINavigationController *)self.window.rootViewController;
MyMasterViewController *firstViewController = (MyMasterViewController *)[[navigationController viewControllers] objectAtIndex:0];
MyDataController *aDataController = [[MyDataController alloc] init];
firstViewController.dataController = aDataController;
return YES;
}
from ViewController:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
//would this go here?
dispatch_async(dispatch_get_main_queue(), ^{
MyObject *objectAtIndex = [self.dataController objectInListAtIndex:indexPath.row];
[[cell textLabel] setText:objectAtIndex.name];
});
return cell;
}
In case you couldn't tell I'm really new to iOS and Objective C. Any help or hints you can give would be greatly appreciated. I'm not even sure if I'm expressing my question properly - it just seems that what I want to do shouldn't be this difficult. Thanks!
EDIT
Ok, so maybe this is a life cycle issue. Just realized that anything I set within the async block is nil outside the block, at least it is until it's too late to make a difference. That's why cellForRowAtIndexPath is never called - because the masterDataList being passed to the UITableView is empty. Tested this by initializing
__block NSString *s = [[NSString alloc] init];
outside the block, then setting a value inside the block:
s = #"Testing...";
and finally NSLogging the value of s after the block has supposedly run. But obviously the block hadn't run yet because s was nil.
It looks like you're doing the right thing to get back on the main thread after your work is done, but you haven't told the table view it needs to show the new data. [self.tableView reloadData] ought to help.
As I discovered in posts such as this one, data set within the async dispatch cannot be used outside the queue. As I understand it, the whole idea of GCD is that it determines when it's best to run and dispose of data.
As a result, I ended up splitting up my code so I was only using the DataController class to, well, control data (I know, revolutionary) and moved all the GCD parts to my ViewController. Amended code:
DataController class:
- (void)initializeDefaultDataList {
NSMutableArray *dataList = [[NSMutableArray alloc] init];
self.masterDataList = dataList;
}
ViewController class:
#interface ObjectMasterViewController () {
__block NSString *jsonString;
}
#end
...
- (void)getJSONString
{
jsonString = [JSONHelper JSONpostString:#"http://webservice/getData"];
}
...
- (void)initData {
NSError *jsonError = nil;
//convert string to dictionary using NSJSONSerialization
NSDictionary *jsonResults = [NSJSONSerialization JSONObjectWithData: [jsonString dataUsingEncoding:NSUTF8StringEncoding]
options: NSJSONReadingMutableContainers
error: &jsonError];
if (jsonError) NSLog(#"[%# %#] JSON error: %#", NSStringFromClass([self class]), NSStringFromSelector(_cmd), jsonError.localizedDescription);
NSArray *dataArray = [jsonResults objectForKey:#"d"];
//loop through array and add items to list
for (NSString *dataItem in dataArray) {
[self addDataWithItem:dataItem];
}
}
...
- (void)viewDidLoad
{
[super viewDidLoad];
dispatch_queue_t myQueue = dispatch_queue_create("name.queue.my", NULL);
dispatch_async(myQueue, ^{
//initalize service url string
[self getJSONString];
dispatch_async(dispatch_get_main_queue(), ^{
//retrieve data
[self initData];
//reload tableView with new data
[self.tableView reloadData];
});
});
}
Hope this can help someone who might be in the same boat I was in.
This is yet another EXC_BAD_ACCESS question. Although I've done my homework and am certain that I am not over-releasing my NSArray.
So here is a snippet of my code:
tableData = [NSDictionary dictionaryWithJSONString:JSONstring error:&error];
//Collect Information from JSON String into Dictionary. Value returns a mutli
dimensional NSDictionary. Eg: { value => { value => "null"}, etc }
NSMutableArray *t_info = [[NSMutableArray alloc] init];
for(id theKey in tableData)
{
NSDictionary *get = [tableData objectForKey:theKey];
[t_info addObject:get];
[get release];
} // converting into an NSArray for use in a UITableView
NSLog(#"%#", t_info);
//This returns an Array with the NSDictionary's as an Object in each row. Returns fine
if (tvc == nil)
{
tvc = [[tableViewController alloc] init]; //Create Table Controller
tableView.delegate = tvc;
tableView.dataSource = tvc;
tvc.tableView = self.tableView;
tvc.tableData = t_info; //pass our data to the tvc class
[tvc.tableView reloadData];
}
...
Now in my TableViewController Class:
#implementation tableViewController
#synthesize tableData, tableView;
- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [tableData count]; //Returns X Amount Fine.
}
- (UITableViewCell *)tableView:(UITableView *)the_tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
NSString *MyIdentifier = [NSString stringWithFormat:#"MyIdentifier"];
UITableViewCell *cell = [the_tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:MyIdentifier] autorelease];
}
NSLog(#"%#", tableData); //** CRASHES!!**
cell.textLabel.text = #"This is a test";
return cell;
}
If I were to comment out that NSLog, it'll work fine and return "this is a test" on each table row.
This one has really got me stumped, all the articles I have around about this problem is generally related to retain/memory issues.
Also, another important point.
If I were to pass through my original (NSDictionary) tableData from my first class code and run the same script in my tableViewController - I can NSLog the object perfectly fine.
The only time you need to release an object is if you have explicitly allocated it by way of new, alloc, or copy.
NSMutableArray *t_info = [[NSMutableArray alloc] init];
for(id theKey in tableData)
{
NSDictionary *get = [tableData objectForKey:theKey];
[t_info addObject:get];
[get release];
}
You shouldn't be releasing get here. By doing this, you're releasing the reference that the tableData dictionary is holding onto, which is bad. My guess is that this is what is causing the problem that you're encountering.
If I'm not mistaken, the reason why [tableData count] returns the expected value is because the array is still holding onto the references that have been released.
I'm having problems with memory leaks with this function. I thought creating an NSArray with componentsSeparatedByString was autorelease but instruments seems to indicate a leak at the NSArray aPair. Why would it indicate a leak there and not also at the other NSArrays created in the same way?
-(void) checkRequest: (NSString *)request view:(UIViewController *)theView webView:(UIWebView *)wView
{
//NSLog(#"JSResponder - checkRequest()");
NSString *aRequest = [NSString stringWithString:request];
NSArray *urlArray = [aRequest componentsSeparatedByString:#"?"];
if([urlArray count] > 1)
{
NSString *paramsString = [urlArray lastObject];
NSString *cmd = #"";
NSArray *urlParamsArray = [paramsString componentsSeparatedByString:#"&"];
int numCommands = [urlParamsArray count];
NSMutableDictionary *paramsWithNames = [[NSMutableDictionary alloc ] initWithCapacity:numCommands];
for (NSString *elementPair in urlParamsArray)
{
NSArray *aPair = [elementPair componentsSeparatedByString:#"="];
NSString *aKey = [aPair objectAtIndex:0];
NSString *aParam = [aPair objectAtIndex:1];
if([aKey compare:#"_command"] == NSOrderedSame)
{
cmd = aParam;
}
else
{
[paramsWithNames setValue: aParam forKey:aKey];
}
}
[self executeCommand: cmd withParams: paramsWithNames view:theView webView:wView];
[paramsWithNames release];
}
}
This function get called by the following:
- (void)pullJSEvent:(NSTimer*)theTimer
{
NSLog(#"MainView - pullJSEvent()");
NSString *jsCall = [NSString stringWithString:#"if(typeof checkOBJCEvents == 'function'){checkOBJCEvents();}"];
NSString *jsAnswer = [[webView stringByEvaluatingJavaScriptFromString:jsCall] retain];
if([jsAnswer compare:#"none"] != NSOrderedSame)
{
//NSLog(#" answer => %#", jsAnswer);
[jsResponder checkRequest:jsAnswer view:(UIViewController *)self webView:self.webView];
}
[jsAnswer release];
}
Thank-you
You're going to have to dig a bit deeper with the Leaks instrument. You're leaking one of the strings in the array, not the array itself. Leaks indicates that line because that's where the strings in the array are allocated.
Go into Leaks, look at a leaked instance, and click that little arrow button. You'll see all the retains and releases of the leaked object, which should point you to the problem.
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];
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
//NSLog(#"Array: %#",rows);
return [rows count];// AT THIS LINE
}
Program received signal: “EXC_BAD_ACCESS”
THANKS FOR THE REPLY
Actually I have attached it to the WebPage By NSUrl where I have made a PHP array and I have created a NSLOG where I am getting the Values in the array form but When It exceute the line return [rows count];. It gives error when I am writting statically return 2; then it execute. I am explaining to you what I am doing. I am initialising the NIb with
Name tableViewController=[[JsonTestViewController alloc] initWithNibName:#"JsonTestViewController" bundle:nil];
In JsonTestViewController.m
I have this code:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
//NSLog(#"Array: %#",rows);
return [rows count];
}
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
// Configure the cell.
NSDictionary *dict = [rows objectAtIndex: indexPath.row];
NSString *strlb1=[dict objectForKey:#"block"];
NSString *strlb2=[dict objectForKey:#"name"];
strlb1=[strlb1 stringByAppendingString:#" , "];
strlb1=[strlb1 stringByAppendingString:strlb2];
NSString *str1=#"FPS : ";
NSString *str2=[dict objectForKey:#"p_hours"];
NSString *strpinf;
if([str2 isEqualToString:#"FP"])
{
strpinf=#"Free Parking";
}
else if([str2 isEqualToString:#"12"])
{
strpinf=#"2 hours";
}
else if([str2 isEqualToString:#"14"])
{
strpinf=#"4 hours";
}
else if([str2 isEqualToString:#"MP"])
{
strpinf=#"Metered Parking";
}
str1=[str1 stringByAppendingString:strpinf];
cell.textLabel.text =strlb1;
cell.detailTextLabel.text = str1;
return cell;
}
- (void)viewDidLoad {
[super viewDidLoad];
NSURL *url = [NSURL URLWithString:#"SITE URL"];
NSString *jsonreturn = [[NSString alloc] initWithContentsOfURL:url];
NSData *jsonData = [jsonreturn dataUsingEncoding:NSUTF32BigEndianStringEncoding];
NSError *error = nil;
NSDictionary * dict = [[CJSONDeserializer deserializer] deserializeAsDictionary:jsonData error:&error];
if (dict)
{
rows = [dict objectForKey:#"users"];
}
NSLog(#"Array: %#",rows);
[jsonreturn release];
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)dealloc {
[super dealloc];
}
#end
can you give more info? This can be anything, but most likely, rows is pointing to memory where a valid array used to be. How did you create the rows array?
For example, your rows array or dictionary not longer pointing to valid memory if you created the rows array as an autoreleased object through a factory method in another method.
Here's another question that's pretty close to what you're describing:
EXC_BAD_ACCESS signal received
EDIT:
So looking at the code you provided, with these lines there are some possibilities:
NSDictionary * dict = [[CJSONDeserializer deserializer] deserializeAsDictionary:jsonData error:&error];
if (dict) { rows = [dict objectForKey:#"users"]; }
the deserializeAsDictionary method can return either an autoreleased dictionary or NULL. so one possibility is that rows = NULL. when you try [rows count], your program will crash. Check and see what's in error, might give you some clues.
This will cause an error even when you explicitly return 2 for numberOfRowsInSection: because in cellForRowAtIndexPath:, you're still trying to access rows, even if it could possibly be NULL.
the other possibility lies in how you've defined rows. I'm guessing it's a property in your class. But where you have rows=[dict objectForKey:#"users"];, rows can point to nothing after the method's finished. Rows will still have the address of where [dict objectForKey:] was, but after the scope of the method, dict may be gone and all the data that comes with it.
NSDictionary * dict = [[CJSONDeserializer deserializer] deserializeAsDictionary:jsonData error:&error];
under the KVC guidelines, you should expect dict to autorelease after the end of method.
and another possibility is, since i don't know the specifics of the JSON class you're using, is that when you release jsonreturn, you're also dealloc'ing all the data associated with it. So in effect, rows is pointing to nothing.
case in point, the error seems to be rooted in how you're setting/retaining/accessing rows.
try using the Build->Build&Analyze in xcode. it might give you some more hints. or throw in a bunch of NSLog(#"%d",[rows count]); all over. also try using the debugger. it'll give you a trace of method calls that lead up to [rows count] faulting.