Trouble initialising NSMutableArray with NSString

Question

I'm having problem initialising an NSMutableArray called _entryArray with 2 NSString objects @"00:00:00". I'm getting the following error:

Terminating app due to uncaught exception 'NSRangeException', reason: '* -[__NSArrayM objectAtIndex:]: index 1 beyond bounds for empty array'

When I try to initialise it without any objects in it, I get no errors. What do I do?

Thank you very much

code:

@implementation MainViewController{

@private
int n;
NSMutableArray *_entryArray;
NSMutableArray *_timeSinceLastEntryArray;
NSMutableArray *_timeInterval;
NSMutableArray *_timeInBackup;
NSMutableArray *_timeOutBackup;
BOOL whichButton;


}
-(void)viewWillAppear:(BOOL)animated {

}

- (void)viewDidLoad
{
    [super viewDidLoad];
    n=0;
    _brain = [[Brain alloc] init];
    _entryArray = [[NSMutableArray alloc] initWithObjects:@"00:00:00",@"00:00:00",nil];
    _timeSinceLastEntryArray = [[NSMutableArray alloc] init];
    _timeInBackup = [[NSMutableArray alloc] initWithObjects:(NSNumber *)0, nil];
    _timeOutBackup = [[NSMutableArray alloc] initWithObjects:(NSNumber *)0, nil];
    _timeInterval = [[NSMutableArray alloc] init];


    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]
                                   initWithTarget:self
                                   action:@selector(dismissKeyboard)];

    [self.view addGestureRecognizer:tap];
}

What statement is giving you the exception you quote? (Certainly not one of the statements you've listed above.) — Hot Licks
– Hot Licks, Commented Mar 22, 2013 at 1:25
_timeInBackup = [[NSMutableArray alloc] initWithObjects:(NSNumber *)0, nil]; should be _timeInBackup = [[NSMutableArray alloc] initWithObjects:@0, nil]; or in the old syntax _timeInBackup = [[NSMutableArray alloc] initWithObjects:[NSNumber numberWithInt:0], nil]; same goes for _timeOutBackup. — Sergey Kalinichenko
– Sergey Kalinichenko, Commented Mar 22, 2013 at 1:27
(However, you might learn something if you NSLog the arrays you created. _timeInBackup and _timeOutBackup do not contain the values you think they do.) — Hot Licks
– Hot Licks, Commented Mar 22, 2013 at 1:27
That's what I can't figure out. I don't get it if I initialise the _entryArray with just [[NSMutableArray alloc] init], but if I try to initialise it with objects the app wont even start — Fabio
– Fabio, Commented Mar 22, 2013 at 1:28
_entryArray is OK. But NSLog everything, so you understand what you have. — Hot Licks
– Hot Licks, Commented Mar 22, 2013 at 1:29

rmaddy · Accepted Answer · 2013-03-22 02:44:57Z

4

These two lines result in arrays with zero objects:

_timeInBackup = [[NSMutableArray alloc] initWithObjects:(NSNumber *)0, nil];
_timeOutBackup = [[NSMutableArray alloc] initWithObjects:(NSNumber *)0, nil];

You are not adding the number 0, you are adding the pointer 0. This is the same as nil. In other words, this code is really this:

_timeInBackup = [[NSMutableArray alloc] initWithObjects:nil, nil];
_timeOutBackup = [[NSMutableArray alloc] initWithObjects:nil, nil];

If your intent is to add the number 0, do this:

_timeInBackup = [[NSMutableArray alloc] initWithObjects:[NSNumber numberWithInt:0], nil];
_timeOutBackup = [[NSMutableArray alloc] initWithObjects:[NSNumber numberWithInt:0], nil];

Better yet, do this:

_timeInBackup = [@[ @0 ] mutableCopy];
_timeOutBackup = [@[ @0 ] mutableCopy];

You also have other empty arrays:_timeSinceLastEntryArray and _timeInterval. None of the code you have posted is actually causing the error. You need to provide more details to know for sure which array is really causing you the problem.

edited Mar 22, 2013 at 2:44

answered Mar 22, 2013 at 1:33

rmaddy

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2 Comments

Bryan Chen Over a year ago

should be [ @[ @0 ] mutableCopy]

rmaddy Over a year ago

@xlc Thanks for noticing the typo. Fixed.

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