iOS - object sent autorelease too many times - objective-c

Question

I have a method that is reading some information from a sqlite db and initialising a class called Achievement. When I analyse this code I am given the feedback 'object sent autorelease too many times'. I don't really understand where I am going wrong - why is the retval object released on line 225 and not at the return statement on line 229?
Can someone please explain where I have made a mistake in the code below and how I can fix it?
Function Code (so answerer can easily copy/paste):
- (Achievement *)getAchievement:(int)Id
{
Achievement *retval = [[Achievement alloc] autorelease];
NSString *query = [NSString stringWithFormat:#"SELECT * FROM Achievements where ID = %d", Id];
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(_database, [query UTF8String], -1, &statement, nil)
== SQLITE_OK) {
while (sqlite3_step(statement) == SQLITE_ROW) {
int Id = sqlite3_column_int(statement, 0);
char *name = (char *) sqlite3_column_text(statement, 1);
char *title = (char *) sqlite3_column_text(statement, 2);
char *description = (char *) sqlite3_column_text(statement, 3);
Boolean Achieved;
char *com = (char *) sqlite3_column_text(statement, 4);
NSString *c1 = [[[NSString alloc] initWithUTF8String:com] autorelease];
Achieved = [c1 isEqualToString:#"1"];
NSDate *CompletedDate = (NSDate *) sqlite3_column_text(statement, 5);
char *icon = (char *) sqlite3_column_text(statement, 6);
int New = sqlite3_column_int(statement, 7);
NSString *Title = [[[NSString alloc] initWithUTF8String:title] autorelease];
NSString *Description = [[[NSString alloc] initWithUTF8String:description] autorelease];
NSString *Name = [[[NSString alloc] initWithUTF8String:name] autorelease];
NSString *Icon = [[[NSString alloc] initWithUTF8String:icon] autorelease];
retval = [retval initDetails:Id :Name :Title: Description : Achieved : CompletedDate: Icon: New];
}
sqlite3_finalize(statement);
}
return retval;
}
Analysis feedback image:
As always any feedback is greatly appreciated.

Answer 1

Achievement *retval = [[Achievement alloc] autorelease];
this is very bad idea to do that. You ALWAYS have to initialize object before using it.
Instead you're initializing it in a loop:
retval = [retval initDetails:Id :Name :Title: Description : Achieved : CompletedDate: Icon: New];
I don't really get why you need to initialize the same object multiple times. Maybe, you need to create multiple objects and init them with different values?
Rearrange this:
Achievement *retval = nil;
while (...) {
[retval release];
retval = [[Achievement alloc] initDetails: ...];
}
return [retval autorelease];

Answer 2

I guess you're confusing the compiler with the wrong sequence of alloc, init, autorelease. What you should be doing instead is the following (pseudocode):
Achievement *retval = nil;
while (...) {
retval = [[[Achievement alloc] initDetails: ...] autorelease];
}
return retval;