Im using dictionary to save some positions with value "1";
/* * * header * * */
NSDictionary *Mypoints;
/* * * * * * * * */
-(void)myfunc: (float)y :(float)x{
NSLog(#"%#",Mypoints);
NSNumber *one = [NSNumber numberWithInt:1];
NSString *key = [[NSString alloc] initWithFormat:#"%f,%f",y,x];
[Mypoints setObject:one forKey:key];
//show the value
NSNumber *tempNum = [Mypoints objectForKey:key];
int i = tempNum.intValue;
NSLog(#"Value: %i",i);
//print all
NSLog(#"%#",Mypoints);
}
The first time that I call this function everything is okay, it creates the dictionary and print the "array" in last line. But when I enter this function again, it crashes with no error.
I don't know what may be happening...
I solved the crash doing it:
Mypoints = [[NSMutableDictionary dictionaryWithObject:one forKey:key]retain];
I solved how to add more points:
//into viewDidLoad
Mypoints = [[NSMutableDictionary alloc] init];
//into myfunc
[Mypoints setObject:one forKey:key];
Mypoints is not getting retained. So the first time it will be nil, the second time Mypoints will be pointing to memory which was freed.
Other minor issues in this code:
Mypoints should be set to nil before use (I assume this is done elsewhere).
Mypoints = [NSDictionary dictionaryWithObject:one forKey:key]; Your dictionary will also only contain 1 key/value pair because you are creating a new dictionary every time.
NSString *key = [[NSString alloc] initWithFormat:#"%f,%f",y,x]; This will leak, as it is not being released.
// Not keen on this being a global but whatever... It needs to be initialised somewhere in this example.
NSMutableDictionary* Mypoints = nil;
-(void)myfunc: (float)y :(float)x
{
// This is hacky but shows the principle.
if ( Mypoints == nil )
{
Mypoints = [ NSMutableDictionary alloc ] initWithCapacity: 10 ];
// Or whatever you think the size might be. Don't forget to release it somewhere.
}
NSNumber *one = [NSNumber numberWithInt:1];
NSString *key = [NSString stringWithFormat:#"%f,%f",y,x];
// This stops the leak since it is now already autoreleased.
[ MyPoints setObject: one forKey: key ]; // Be careful no other key can have the same x and y value.
//show the value
NSNumber *tempNum = [Mypoints objectForKey:key];
int i = tempNum.intValue;
NSLog(#"Value: %i",i);
//print all
NSLog(#"%#",Mypoints);
}
Because [NSDictionary dictionaryWithObject:one forKey:key] returns an autoreleased object, which gets released sometime between invocations of -myfunc:. The crash is obviously happening on the first line with NSLog().
Related
I am using XCode for developing an iPhone app. I am new to this platform and need some help with a particular issue...
I have a method that processes some data and returns two integer values as NSNumber wrapped into a NSMutableArray.
Here is the method:
-(NSMutableArray *)processPoints:(int) x:(int) y
{
NSMutableArray *mutArray = [[NSMutableArray alloc] initWithCapacity:3];
int x9,y9;
// ...do some processing...
NSNumber* xNum = [NSNumber numberWithInt:x9];
NSNumber* yNum = [NSNumber numberWithInt:y9];
[mutArray addObject:xNum];
[mutArray addObject:yNum];
return [mutArray autorelease];
}
I call the above method from another method, where I copy the NSNumber stuff into local variables and then release the local copy of NSMutable array.
But the app crashes when releasing this NSMutable array (variable 'mutArray').
Here is the method:
-(void)doNinjaAction
{
NSMutableArray* mutArray = [self processPoints: x :y];
NSNumber* s1 = [[mutArray objectAtIndex:0] retain];
NSNumber* s2 = [[mutArray objectAtIndex:1] retain];
x = [s1 integerValue];
y = [s2 integerValue];
//...proceed with other stuff...
[mutArray autorelease]; //this is where the system crashes. same for 'release'
//instead of 'autorelease'
}
Can you please explain where I am going wrong with the process of memory release.
My understanding of the process is a bit shaky. Please help.
Because you're overreleasing the array. You alloc-init it in processPoints:, then you autorelease it - that's correct, this is how you dispose of its ownership.
After that, you don't need to and must not autorelease or release it once again. This is not malloc() from the standard library.
when you call the statement
NSMutableArray* mutArray = [self processPoints: x :y];
This itself acts as autorelease.
Hence releasing the array explicitly will cause the app to crash.
You are releasing mutArray more then once. Once in processPoints function and again in doNinjaAction.
To resolve the crash remove :
[mutArray autorelease];
-(NSMutableArray *)processPoints:(int) x:(int) y
{
NSMutableArray *mutArray = [[NSMutableArray alloc] initWithCapacity:3];
int x9,y9;
// ...do some processing...
NSNumber* xNum = [NSNumber numberWithInt:x9];
NSNumber* yNum = [NSNumber numberWithInt:y9];
[mutArray addObject:xNum];
[mutArray addObject:yNum];
[mutArray autorelase];
return mutArray;
}
try this one it'll resolve it.
-(NSMutableArray *)processPoints:(int) x:(int) y
{
NSMutableArray *mutArray =[[[NSMutableArray alloc] initWithCapacity:3]autorelease];
int x9,y9;
// ...do some processing...
NSNumber* xNum = [NSNumber numberWithInt:x9];
NSNumber* yNum = [NSNumber numberWithInt:y9];
[mutArray addObject:xNum];
[mutArray addObject:yNum];
return mutArray;
}
As #H2CO3 and #AppleDelegate suggested, it is right.
Still I would suggest to use ARC and convert your project to ARC enabled.
Go to Edit->Refactor->Convert to Objectiv-C ARC
Then you dont need to do any releases anywhere. It will take care itself of all the releases :)
I found a workaround myself, but still trying to understand the problem.
I created a Autocomplete text field with the use of uitableview which is hidden until textfield is edited. The UI part works fine. It's the searching for the results part that's the problem. I declared a local NSMutableDictionary to store my results because I wanted the results to be sorted by the key's values.
if I call keysSortedByValueUsingSelector on the dictionary directly, it crashes. However if I get the keys by [dict allKeys] first, then call sortedArrayUsingSelector, it works fine:
// This commented out line will crash
// NSArray *sortedKeysArray = [dict keysSortedByValueUsingSelector:#selector(compare:)];
// The next two lines runs fine.
NSArray *keyArray = [dict allKeys];
NSArray *sortedKeysArray = [keyArray sortedArrayUsingSelector:#selector(compare:)];
Here is the complete source code for the search method:
- (void)searchAutocompleteEntriesWithSubstring:(NSString *)substring
{
// Put anything that starts with this substring into the autocompleteUrls array
// The items in this array is what will show up in the table view
[autocomplete_symbol_array removeAllObjects];
rRSIAppDelegate *appDelegate = (rRSIAppDelegate *)([[UIApplication sharedApplication] delegate]);
NSString *input_str = [substring uppercaseString];
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
int i = 0;
for(SymbolInfo *symbol_info in appDelegate.m_symbol_info_array)
{
i++;
NSString *info_str = [[[symbol_info.m_symbol uppercaseString] stringByAppendingString:#"|"] stringByAppendingString:[symbol_info.m_company_name uppercaseString]];
NSUInteger pos = [info_str rangeOfString:input_str].location;
if (pos != NSNotFound)
{
int tmp = pos * 10000 + i;
NSNumber *map_key = [[NSNumber alloc] initWithInt:tmp];
[dict setObject:symbol_info forKey:map_key];
}
}
// This commented out line will crash
// NSArray *sortedKeysArray = [dict keysSortedByValueUsingSelector:#selector(compare:)];
// The next two lines runs fine.
NSArray *keyArray = [dict allKeys];
NSArray *sortedKeysArray = [keyArray sortedArrayUsingSelector:#selector(compare:)];
for (NSNumber *key in sortedKeysArray)
{
SymbolInfo *symbol_info = [dict objectForKey:key];
[autocomplete_symbol_array addObject:symbol_info];
}
// NSLog(#"everything added: %d", [autocomplete_symbol_array count]);
[autocompleteTableView reloadData];
}
The NSMutableDictionary's method is:
- (void)setObject:(id)anObject forKey:(id < NSCopying >)aKey;
This means that the key should implement the NSCopying protocol.
I'm using this code with ARC:
NSMutableDictionary *datesDict = [[NSMutableDictionary alloc]init];
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
for (NSString *key in programsArray) {
datesArray = [_onDemandDictionary objectForKey:key];
NSMutableArray *newDates = [[NSMutableArray alloc]init];
int count;
for (count = 0; count <datesArray.count; count++) {
NSMutableDictionary *programsDict = [[NSMutableDictionary alloc]init];
programsDict = [datesArray objectAtIndex:count];
[newDates addObject:[programsDict objectForKey:#"date"]];
}
[datesDict setObject:newDates forKey:key];
}
But when I run the analyzer tool I'm getting value stored to (datesArray and programsDict) during its initialization is never read on lines:
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
programsDict = [datesArray objectAtIndex:count];
Why is this happening how do I get hid of the warning?
Thank you!
The issue is you create a new NSMutableArray and assign it to datesArray at the beginning
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
Then almost immediately after you assign a completely different value to datesArray with
datesArray = [_onDemandDictionary objectForKey:key];
I would just start with
NSMutableArray *datesArray = nil;
It's the same concept for programsDict.
On line 2, you create a new array datesArray.
Then, on line 6 (first line of the for loop), you set a new value to datesArray.
The compiler is just warning you that the line 2 has no effect, and that the code is bugged (in the sense it does not do what you expect).
True, the programsArray could be an empty array, and in this case you want datesArray to just be initialized to use it after the snippet you showed us, but it would be better to make this explicit.
For programsDict, it is even easier: you initialize it with ... alloc] init] then set it to an object of datesArray, making the first operation useless.
You are not using datesArray in your loop, you are simply assigning it values, So either take it nil array like
NSMutableArray* datesArray = nil;
or like
NSMutableArray *datesArray;
to remove waring .
I eliminated all the leaks from my current app. However Instruments constantly tells me that I have a leak in the method shown below.
The leak is of type NSMutableArray and has a size of either 16 or 32 bytes. Yes, I know that's not much but it adds up. Also see it as an academic question that I need to solve to make my code leakless.
+ (id) meterFromDict:(NSDictionary*)dict {
Meter* resMeter = [[Meter alloc] initWithType:[[dict objectForKey:#"MeterBase"] intValue]];
//NSLog(#"dict: %#",dict);
resMeter.volume = nil;
resMeter.sounds = nil;
resMeter.repeats = nil;
resMeter.volume = [[[NSMutableArray alloc] initWithArray:[dict objectForKey:#"volumeArray"]] autorelease];
resMeter.sounds = [[[NSMutableArray alloc] initWithArray:[dict objectForKey:#"soundsArray"]] autorelease];
resMeter.repeats = [[[NSMutableArray alloc] initWithArray:[dict objectForKey:#"repeatsArray"]] autorelease];
//NSLog(#"MeterFromDict called and resmeter.repeats count is : %i",[resMeter.repeats count]);
resMeter.bpm = [[dict objectForKey:#"BPM"] floatValue];
return [resMeter autorelease];
}
Without looking at your Instruments output directly I can't tell exactly, but you're writing some redundant code: Try this:
+ (id) meterFromDict:(NSDictionary*)dict {
Meter* resMeter = [[Meter alloc] initWithType:[[dict objectForKey:#"MeterBase"] intValue]];
//NSLog(#"dict: %#",dict);
resMeter.volume = [dict objectForKey:#"volumeArray"];
resMeter.sounds = [dict objectForKey:#"soundsArray"];
resMeter.repeats = [dict objectForKey:#"repeatsArray"];
//NSLog(#"MeterFromDict called and resmeter.repeats count is : %i",[resMeter.repeats count]);
resMeter.bpm = [[dict objectForKey:#"BPM"] floatValue];
return [resMeter autorelease];
}
There's no point in nilling your properties before assigning new values to them.
Also, No point creating new arrays for arrays that you already have. And if you have properly declared your volume, sounds and repeats properties with copy instead of retain.
Try that and see if it works better.
I'm a beginner at C, Obj-C and the iPhone, and I'm trying getting to grips with a lot of terminology used. I hope one of ye can help with a problem I have been struggling with for a few days now.
My code below is a method which call up a nib containing a search field and a table. The table is populated from a search of the array created for 'theList' below. Using 'Instruments', I am getting a Leak at the line:
NSDictionary *theItem = [NSDictionary dictionaryWithObjectsAndKeys:clientName,#"Name",clientId,#"Id",nil]; , but I can't figure out why :(
I know it's probably a difficult question to answer, but if any one can be of any help!
- (void)editClient:(id)sender {
if (pickList == nil) {
pickList = [[PickFromListViewController alloc] initWithNibName:#"PickList" bundle:nil];
}
TimeLogAppDelegate *appDelegate = (TimeLogAppDelegate *)[[UIApplication sharedApplication] delegate];
NSMutableArray *theList = [[NSMutableArray alloc] init];
int i;
for (i=0;i < [appDelegate.clients count];i++) {
Client *thisClient = [appDelegate.clients objectAtIndex:i];
NSString *clientName = [[NSString alloc] initWithString: thisClient.clientsName];
NSNumber *clientId = [[NSNumber alloc] init];
clientId = [NSNumber numberWithInt:thisClient.clientsId];
NSDictionary *theItem = [NSDictionary dictionaryWithObjectsAndKeys:clientName,#"Name",clientId,#"Id",nil];
[theList addObject:theItem];
theItem = nil;
[clientName release];
[clientId release];
}
[pickList createSearchItems:theList :NSLocalizedString(#"Client",nil)];
[theList release];
appDelegate.returningID = [NSNumber numberWithInt: projectsClientsId];
[self.navigationController pushViewController:pickList animated:YES];
}
Thanks in advance!
This returns allocated NSNumber instance.
NSNumber *clientId = [[NSNumber alloc] init];
This line overwrites the above clientId with another instance of NSNumber, numberWithInt returns autoreleased object, since you haven't allocated memory for it you should not call release, it will be released automatically.
clientId = [NSNumber numberWithInt:thisClient.clientsId];
You are calling release on clientId so you get memory problem.
To fix it remove the first line above which is useless in this case and update the second one to:
NSNumber * clientId = [NSNumber numberWithInt:thisClient.clientsId];
Then remove the:
[clientId release]
Because the clientId will be released automatically.
EDIT: Re still have problems ...
I'm not sure how to you manipulate the clients in app delegate, otherwise the code should work ok, I created small example, omitting the parts that I can't see (app delegate and clients):
// command line utility - foundation tool project:
#import <Foundation/Foundation.h>
int main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
NSMutableArray * theList = [[NSMutableArray alloc] init];
int i = 0;
for (i = 0; i < 10; ++i)
{
NSString * clientName = [NSString stringWithString:#"client"]; //no need to release
NSNumber * clientId = [NSNumber numberWithInt:i];
NSDictionary * theItem = [NSDictionary dictionaryWithObjectsAndKeys:
clientName, #"name",
clientId, #"id",
nil];
[theList addObject:theItem];
}
for (id item in theList) for (id key in item) NSLog(#"%# - %#", key, [item objectForKey:key]);
[theList release];
[pool drain];
return 0;
}
You are creating clientID with [[NSNumber alloc] init], and then immediately overwriting it with an autoreleased NSNumber instance [NSNumber numberWithInt], and then you are releasing it later in your code, which you shouldn't do. Get rid of the [[NSNumber alloc] init] line and the [clientId release] line and that should fix it up a little.
Aside from the obvious leak of the NSNumber, there are a few other things I'd fix that may help. Most are fairly minor, but in my experience with Objective-C, less code == clearer code, something that is not equally true for languages like Bash or Perl. ;-)
- (void) editClient:(id)sender {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
if (pickList == nil) {
pickList = [[PickFromListViewController alloc] initWithNibName:#"PickList" bundle:nil];
}
TimeLogAppDelegate *appDelegate = (TimeLogAppDelegate*)[[UIApplication sharedApplication] delegate];
NSMutableArray *searchItems = [NSMutableArray array];
NSMutableDictionary *itemDict = [NSMutableDictionary dictionary];
for (Client *client in appDelegate.clients) {
[itemDict setObject:[client.clientsName copy] forKey:#"Name"];
[itemDict setObject:[NSNumber numberWithInt:client.clientsId] forKey:#"Id"];
[searchItems addObject:[[itemDict copy] autorelease]];
}
[pickList createSearchItems:searchItems :NSLocalizedString(#"Client",nil)];
[self.navigationController pushViewController:pickList animated:YES];
appDelegate.returningID = [NSNumber numberWithInt: projectsClientsId];
[pool drain];
}
There are a few mysterious points that make me suspicious:
The line just after the for loop tells pickList to do something with the NSMutableArray. That method should retain the new array, as well as release the old array if one exists. If you just overwrite the pointer, the old array will be leaked. (Also, this method is poorly named. Anonymous arguments (a colon with no preceding text) are legal in Objective-C, but considered extremely bad practice. Consider renaming the method to better express what it does.)
The next line seems to associate the pick list with a navigation controller. If it is custom code, make sure the -pushViewController:animated: method properly releases an existing pick list when a new one is specified.
Assigning to appDelegate.returningID is assumed to call the setter for a returningID property. Be sure that property retains or copies the NSNumber as necessary.
Memory leaks can be tricky to track down, even in Instruments, and you'll often find that it looks like Foundation classes (such as NSDictionary) are leaking like a sieve, but I have always been able to trace it back to an abnormality in my code. :-)