This is really twisting my mind… I'm trying to access an NSMutableArray in an IBAction which I defined in viewDidLoad. Unfortunately I keep getting a EXC_BAD_ACCESS.
I'm new to all this so I'd really appreciate some insight in what I'm doing wrong.
Below find the corresponding code excerpts.
CounterViewController.h:
#interface CounterViewController : UIViewController{
NSMutableArray *countHistoryArray;
}
#property(nonatomic, retain) NSMutableArray *countHistoryArray;
CounterViewController.m:
#implementation CounterViewController
#synthesize countHistoryArray;
- (void)viewDidLoad {
[super viewDidLoad];
//Fill array with some dummy data
self.countHistoryArray = [[NSMutableArray alloc] init];
NSDate *now = [[[NSDate alloc] init] autorelease];
CurrentCount *historicCount = [[[CurrentCount alloc]
initWithCount:[NSNumber numberWithInteger:22]
description:#"Testcount"
dateAndTime:now] autorelease];
[self.countHistoryArray addObject: historicCount];
//Do some logging - everything is working fine here!
NSLog(#"%#", [self.countHistoryArray description]);
}
//Later on we click on a button and want to use the array
- (IBAction)doSomeStuff {
//Let's look at the array again - and now it crashes with EXC_BAD_ACCESS
NSLog(#"%#", [self.countHistoryArray description]);
}
Thanks a lot!
Manuel
EDIT Additional code as asked for by #jamapag
CurrentCount.h
#import <Foundation/Foundation.h>
#interface CurrentCount : NSObject {
NSNumber *counterLevel;
NSString *description;
NSDate *dateAndTime;
}
- (id)initWithCount:(NSNumber *)newCounterLevel description:(NSString *)newDescription dateAndTime:(NSDate *)newDateAndTime;
#property(nonatomic, copy) NSNumber *counterLevel;
#property(nonatomic, copy) NSString *description;
#property(nonatomic, copy) NSDate *dateAndTime;
#end
CurrentCount.m
#import "CurrentCount.h"
#implementation CurrentCount
#synthesize counterLevel;
#synthesize description;
#synthesize dateAndTime;
- (id)initWithCount:(NSNumber *)newCounterLevel description:(NSString *)newDescription dateAndTime:(NSDate *)newDateAndTime{
self = [super init];
if(nil != self){
self.counterLevel = newCounterLevel;
self.description = newDescription;
self.dateAndTime = newDateAndTime;
}
return self;
}
-(void) dealloc{
self.counterLevel = nil;
self.description = nil;
self.dateAndTime = nil;
[super dealloc];
}
#end
Are you sure that your code actually looks like this?
- (IBAction)doSomeStuff {
//Let's look at the array again - and now it crashes with EXC_BAD_ACCESS
NSLog(#"%#", [self.countHistoryArray description]);
}
Your question title says "NSMutableArray count causes EXC_BAD_ACCESS" - if that line of code actually says NSLog(#"%#", [self.countHistoryArray count]);, you'll almost certainly get a crash, since NSLog will attempt to treat a primitive type (the type returned by -[NSArray count]) as an object. In order to use -[NSArray count] in NSLog, use %u instead of %#:
- (IBAction)doSomeStuff {
// This time it should work!
NSLog(#"Array Count = %u", [self.countHistoryArray count]);
}
Remove autorelease from:
currentCount *historicCount = [[[CurrentCount alloc]
initWithCount:[NSNumber numberWithInteger:22]
description:#"Testcount"
dateAndTime:now] autorelease];
It looks like you are accidentally releasing countHistoryArray somewhere. Try removing all calls to it except for those two you showed. Additionally you can try enabling zombies to debug the problem.
Oh and by the way you probably don't really want a public NSMutableArray property and if you do you probably want it to be copy, not retain. Otherwise incapsulation kinda goes down the drain.
I know this question has already been solved and accepted but its for others who are or will face this issue.
I was facing the same issue, I tried all solutions but no solution worked for me. The project I am working on is NON-ARC.
I tried and made a simple change in property
Previously my property for NSMUTABLEARRAY was
#property (nonatomic, assign) NSMutableArray * dataArray;
I changed it to:
#property (nonatomic, retain) NSMutableArray * dataArray;
Changed it from ASSIGN to RETAIN
And it solved my problem
Related
I have recently inherited a large project using an sqlite3 database and currently I am muscling through a significant amount of memory leaks scattered throughout. A couple of the leaks have me confused and demoralised after not being able to solve them. This loop within a method leaks an awful amount of bytes but appears to be so simplistic I simply don't know how to change it to prevent the leak.
...
while ((ret=sqlite3_step(selStmt))==SQLITE_ROW)
{
GraphData *item = [GraphData alloc];
item.key = sqlite3_column_int(selStmt, 0);
item.value = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selStmt,1)];
[newData addObject:item];
[item release], item = nil;
}
...
#interface GraphData : NSObject{
NSInteger key;
NSString *value;
}
#property (nonatomic, readwrite) NSInteger key;
#property (nonatomic, retain) NSString *value;
-(id)initWithPrimaryKey:(NSInteger) xid;
-(id)initWithName:(NSString *)n key:(NSInteger)i;
#end
#import "GraphData.h"
#implementation GraphData
#synthesize key,value;
-(id)initWithPrimaryKey:(NSInteger) xid{
self.key = xid;
self.value = #"";
return self;
}
-(id)initWithName:(NSString *)n key:(NSInteger)i{
self.key = 0;
self.value = n;
return self;
}
#end
Almost all the leaks within this datasource class come from this loop.
I'm hoping this is something trivial that my inexperience has overlooked.
Thanks for taking the time to look at my question.
There's no dealloc in your GraphData class.
- (void)dealloc {
[value release];
[super dealloc];
}
(I assume you're not using ARC because you have release in your first code snippet. I really recommend converting to ARC - this kind of leak vanishes.)
update: I have found the bug in my copyWithZone method in A. Thanks everyone.
update: sorry, I do have the #properties declared, I thought it was obvious so I skipped them in my OP. Sorry about that.
The crash message is: objA was released (zombie) memory when trying to access the str.
My data structure looks like this:
#class A
{
NSString *str;
}
#property (retain) NSString *str; // str synthesized in .m
#class B
{
A *objA;
}
#property (copy) A *objA; // objA synthesized in .m
What I am trying to do is:
B *newB = [[B alloc] init];
[someMutableArray addObject: newB];
However, I will crash some times when I try to access like this:
B *myB = [someMutableArray objectAtIndex: index];
someLabel.text = myB.objA.str;
I guess the objA & objA.str were not retained when inserting B into the array. But I don't know how to make sure they are retrain.
Any help is appreciated
-Leo
You should be using properties for Class A and B:
#interface A : NSObject {
NSString *str;
}
#property (nonatomic, retain) NSString *str;
#end
The use #synthesize str; in .m file, this will retain the str, don't forget to release the str in the dealloc method:
#implementation A
#synthesize str;
- (void) dealloc {
[str release], str= nil;
[super dealloc];
}
#end;
You should look in to
http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjectiveC/Chapters/ocProperties.html%23//apple_ref/doc/uid/TP30001163-CH17
to learn about properties and how they manage memory.
Have you tried:
[someMutableArray addObject: [newB copy] ];
At this line
someLabel.text = myB.A.str;
it should be...
someLabel.text = myB.objA.str;
Yes, also you should be using properties for the members of your class. That will retain them. Just don't forget to release in dealloc
I have an NSMutableArray defined as a property, synthesized and I have assigned a newly created instance of an NSMutableArray. But after this my application always crashes whenever I try adding an object to the NSMutableArray.
Page.h
#interface Page : NSObject
{
NSString *name;
UIImage *image;
NSMutableArray *questions;
}
#property (nonatomic, copy) NSString *name;
#property (nonatomic, retain) UIImage *image;
#property (nonatomic, copy) NSMutableArray *questions;
#end
Page.m
#implementation Page
#synthesize name, image, questions;
#end
Relevant code
Page *testPage = [[Page alloc] init];
testPage.image = [UIImage imageNamed:#"Cooperatief leren Veenman-11.jpg"];
testPage.name = [NSString stringWithString:#"Cooperatief leren Veenman-11.jpg"];
testPage.questions = [[NSMutableArray alloc] init];
[testPage.questions addObject:[NSNumber numberWithFloat:arc4random()]];
The debugger reveals that the moment I use testPage.questions = [[NSMutableArray alloc] init]; the type of testPage.questions changes from NSMutableArray* to __NSArrayL* (or __NSArrayI*, not sure). I suspect this to be the problem, but I find it extremely odd. Anyone know what's happening here?
The problem is that you've declared the property as copy. This means your setter is going to be implemented something like this:
- (void) setQuestions:(NSMutableArray *)array {
if (array != questions) {
[questions release];
questions = [array copy];
}
}
The kicker here is that if you -copy an array (whether immutable or mutable), you will always get an immutable NSArray.
So to fix this, change the property to be retain instead of copy, and also fix this memory leak:
testPage.questions = [[NSMutableArray alloc] init];
It should be:
testPage.questions = [NSMutableArray array];
#property (nonatomic, copy) This setter declaration "copy" probably cast to NSArray why not retain or assign? I would retain anyway
You can also create a mutable copy method like so:
- (void)setQuestions:(NSMutableArray *)newArray
{
if (questions != newArray)
{
[questions release];
questions = [newArray mutableCopy];
}
}
I am getting errors when trying to add items to a NSMutableArray which is encapsulated within an object.
Code follows:
#import <Foundation/Foundation.h>
#interface TestObject : NSObject {
NSMutableArray *myArray;
}
#property (nonatomic, retain) NSMutableArray *myArray;
#end
#import "TestObject.h"
#implementation TestObject
#synthesize myArray;
- (id) init {
if(self= [super init]){
// Initialise the Mutable Array
myArray = [[NSMutableArray alloc] init];
}
return self;
}
- (void) dealloc {
[super dealloc];
[myArray release];
}
#end
Calling:
TestObject *testObject = [[TestObject alloc] init];
NSString *someString = #"blah blah blah";
NSLog(#"%#", someString);
[testObject.myArray addObject:someString];
NSLog(#"Test Object Array Count: %#", [testObject.myArray count]);
[testObject release];
Can anyone tell me why this throws an error when calling count?
I have also tried the copy the Mutable Array to a local variable and get the same result when calling count on the local variable.
Warning warning warning!!!
[super dealloc] is the last thing you should do in your -dealloc method, not the first!
It's a good thing it just showed a warning, when I have done the same it has crashed.
The reason is that %# is an object placeholder. But the count method returns NSInteger which is a primitive datatype and the placeholder for it is %d, as you have correctly noted in the comment.
I am developing iPhone Application.
MyApplicationData.h
#import <Foundation/Foundation.h>
#interface MyApplicationData : NSObject {
NSMutableArray* appData;
}
#property (retain) NSMutableArray* appData;
-(void)loadData;
-(void)addAppDataItemPrice:(NSString*)price itemCategory:(NSString*)category itemDate:(NSDate*)date;
-(void)forDebug;
+(id)instance;
#end
MyApplicationData.m
#import "MyApplicationData.h"
#implementation MyApplicationData
+ (id)instance
{
static MyApplicationData* _instance = nil;
if (!_instance) {
_instance = [[MyApplicationData alloc] init];
}
return _instance;
}
-(void)loadData{
appData = [NSMutableArray array];
NSLog(#"%#",appData);
}
-(void)forDebug{
}
-(void)addAppDataItemPrice:(NSString*)price itemCategory:(NSString*)category itemDate:(NSDate*)date{
NSLog(#"%#", appData);
[appData addObject:#"1"];
NSLog(#"%#", appData);
}
#end
another class
[[MyApplicationData instance] loadData];
one another class
[[MyApplicationData instance] addAppDataItemPrice:price itemCategory:category itemDate:date];
log
[Session started at 2009-11-03 21:04:41 +0900.]
2009-11-03 21:04:44.742 XXX[24002:207] (
)
2009-11-03 21:04:46.612 XXX[24002:207] (null)
It is not executed. What is the cause?
I think this line might be the cause:
appData = [NSMutableArray array];
try this instead:
appData = [[NSMutableArray alloc] init]
You'll want to make sure you release it as well when your MyApplicationData instance is destroyed (not critical in this case since it's a singleton, but still good practice)
It looks like your array is getting autoreleased after the method:
[[MyApplicationData instance] loadData];
I think it should be a member of the class, you can use the property syntax to help.
Set it up in the header file as:
#property (nonatomic, retain) NSMutableArray *appdata;
Then in the implementation:
#synthesize appdata;
Assign it as follows:
-(void)loadData{
self.appData = [NSMutableArray array];
}
Don't forget to release it in your dealloc method
When you set it in your code you can call it like the following:
[self.appData addObject:#"1"];