Singleton in static library in iOS - ios

Question

I have a static library which contains a Singleton class (FMDB SQLite Data Access), now I open from my main application the connection and do thingss... this works, after that a method in my library want to call the a method on my singleton and I get the error that
-[FMDatabase executeQuery:withArgumentsInArray:]: message sent to deallocated instance 0xa443960
is this not possible what I'm trying to achieve?
this is short version of my singleton
static MySingleton* _sharedMySingleton = nil;
FMDatabase *database;
#ifndef __clang_analyzer__
+(MySingleton*)sharedMySingleton
{
#synchronized([MySingleton class])
{
if (!_sharedMySingleton)
[[self alloc] init];
return _sharedMySingleton;
}
}
#endif
+(id)alloc
{
#synchronized([MySingleton class])
{
NSAssert(_sharedMySingleton == nil, #"Attempted to allocate a second instance of a singleton.");
_sharedMySingleton = [super alloc];
return _sharedMySingleton;
}
}
-(Resource *)getResourceForName:(NSString *)name
{
NSString *select = #"SELECT Data, MimeType FROM File WHERE FileName = ? LIMIT 1";
NSArray *arguments = [NSArray arrayWithObject:[NSString stringWithFormat:#"/%#", name]];
FMResultSet *s = [database executeQuery:select withArgumentsInArray:arguments];
if (s == NULL)
{
FuncFileLog(#"getResourceForName file cant be loaded: %#", [database lastErrorMessage]);
return nil;
}
NSData *data = nil;
NSString *mimeType;
while ([s next])
{
data = [NSData dataFromBase64String:[s stringForColumnIndex:0]];
mimeType = [s stringForColumnIndex:1];
}
Resource *resource = [[[Resource alloc] initWithData:data mimeType:mimeType] autorelease];
return resource;
}
-(BOOL)openDatabase
{
database = [FMDatabase databaseWithPath:[self getDocumentResourcePath]];
return [database open];
}
-(void)closeDatabase
{
[database close];
[database release];
}
-(void)dealloc
{
if (database != NULL)
{
[self closeDatabase];
}
[baseUrl release];
[super dealloc];
}
#end
EDIT:
I found that the dealloc from FMDatabase gets called after my application start return, but dont know why.
EDIT2:
Currently I thought one problem was this line
database = [FMDatabase databaseWithPath:[self getDocumentResourcePath]];
here I have to retain the object.

Answer 1

You don't actually assign the singleton instance:
if (!_sharedMySingleton)
[[self alloc] init];
should be:
if (!_sharedMySingleton)
_sharedMySingleton = [[self alloc] init];
and dump that overridden alloc method.
Also database should be an instance variable in the class, and not at global scope.