Question

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

Answer 1

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]);
}