Inexplicable EXC_BAD_ACCESS in the iPhone simulator

Question

I'm trying to build a class for handling all sqlite3 work and I've encountered an EXC_BAD_ACCESS which I just can't explain. I am new to Objective-C development and memory management in general so I apologize if this is a stupid question.

When initializing the class I get the path to the database file and keep it around:

NSArray * documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
databasePath = [[[documentPaths objectAtIndex:0] stringByAppendingPathComponent:@"Database.sql"] retain];

Then I try to use it and it crashes on me:

if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) { // crashes

The odd thing is that the exact same line in a different function works perfectly. I tried adding the variable initialization to above the line, but to no avail:

NSArray * documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
databasePath = [[[documentPaths objectAtIndex:0] stringByAppendingPathComponent:@"Database.sql"] retain];

if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) { // crashes

In both cases the retain count is 2.

However, putting any form of static text in there works fine:

databasePath = @"I have a balloon";
if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) { // fine
// or
if (sqlite3_open([@"APPLES!" UTF8String], &database) == SQLITE_OK) { // fine

A little more experimentation revealed that it was the UTF8String function that was crashing, but I don't understand why.

Edit: Even more experimentation resulted in me being able to call the UTF8String function but not even use the results:

const char * test = [databasePath UTF8String];
NSLog(@"%@", [NSString stringWithUTF8String:test]); // fine
if (sqlite3_open(test, &database) == SQLITE_OK) { // fails

Edit: Messed around even more and discovered that the problem was in a parameter that I was passing to the function. I had breakpoints all over the place so I was 100% sure that the point it fails is at the line I specified, a line which doesn't use the passed variable, but somehow it caused everything to fail. Sometimes. I have no idea how it went wrong, but I rewrote the entire thing, changed my function call and now it works.

Thanks to all who answered.

Answer 1

Try a copy instead of a retain on the variable - it'll make an immutable copy of the string so it shouldn't go changing or disappearing.

EDIT::

What happens when you simply type

if (sqlite3_open[@"myDatabase.sqlite" UTF8String], &database) == SQLITE_OK) {

Also are you sure that the

NSArray * documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
databasePath = [[[documentPaths objectAtIndex:0]
stringByAppendingPathComponent:@"Database.sql"] retain];

is actually returning where the database is?

The code I use to grab the database from the app directory where kFilename is the database file is:

- (NSString *)dataFilePath{

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];

    return [documentsDirectory stringByAppendingPathComponent:kFilename];
}

and then to use it I do:

if(sqlite3_open([[self dataFilePath] UTF8String], &database) != SQLITE_OK){

This works on both my iPod touch and the iPhone simulator.

EDIT2::

I've just used your above method and it seems to work here - I know it sounds stupid but have you tried rebooting? Its possible something strange is happening with the simulator

Answer 2

Have you checked the contents of the databasePath variable before the open call is made? Add an NSLog statement, or use the debugger, to find its value – it could be either NULL, which may not be handled by the sqlite3_open function, or it could even be that the crash is because the path is valid, and the database it points to is corrupt.

Answer 3

My guess is that the database variable is not declared properly. It doesn't seem to have anything to do with the path to the database.

Did you declare database like this?:

sqlite3 *database;

Answer 4

I suspect you are chasing the wrong problem. You haven't shown a crash dump but claim that opening "APPLES!" is 'fine' which sounds odd - surely you don't have a database with that name?

Are you sure you don't have a bad database file lying around - ie, the database file you are trying to open is corrupted in some way?

Answer 5

I think you have to post the crash log, your crash makes no sense. The code you posted should work.