Storing custom class object in Sqlite3 database failed - ios

Question

I want to store a custom class MCOIMAPSession object into sqlite3 database. I read about NSKeyedArchiver and trying to use that like below.
- (void) updateImapSessionForAccount :(NSString *) emailAddress :(MCOIMAPSession *)imapSession {
const char *dbpath = [databasePath UTF8String];
//SQLIte Statement
NSString *selettablequery = [NSString stringWithFormat:#"select * from MailBoxInfoDBTable"];
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
//if(sqlite3_prepare_v2(database, [selettablequery UTF8String], -1, &statement, NULL) == SQLITE_OK)
if (sqlite3_prepare(database, [selettablequery UTF8String], -1, &statement, NULL) ==SQLITE_OK)
{
// Take an array to store all string.
//NSMutableArray *allRows = [[NSMutableArray alloc] init];
while(sqlite3_step(statement) == SQLITE_ROW)
{
char *emailfield = (char *) sqlite3_column_text(statement,0);
NSString *emailStr = [[NSString alloc] initWithUTF8String: emailfield];
NSLog(#"updateMailMessagesPerAccount: %#", emailStr);
if([emailStr isEqualToString:emailAddress])
{
sqlite3_reset(statement);
NSData *messagesData = [NSKeyedArchiver archivedDataWithRootObject:imapSession];
NSString* stringFromData = [messagesData base64EncodedStringWithOptions:0];
NSString *sqlStr = [NSString stringWithFormat:#"update MailBoxInfoDBTable set imapsession='%#' where emailid='%#'", stringFromData, emailAddress];
const char *updateStatement = [sqlStr UTF8String];
if (sqlite3_prepare(database, updateStatement, -1, &statement, NULL) == SQLITE_OK)
{
if(SQLITE_DONE != sqlite3_step(statement))
NSLog(#"Error while updating. %s", sqlite3_errmsg(database));
sqlite3_finalize(statement);
sqlite3_close(database);
return;
}
else
{
NSLog(#"Error in statement: %s", sqlite3_errmsg(database));
}
}
}
}
sqlite3_finalize(statement);
sqlite3_close(database);
}
}
- (MCOIMAPSession *) retrieveImapSessionForAccount :(NSString *) emailAddress {
MCOIMAPSession *imapsessionObj = nil;
const char *dbpath = [databasePath UTF8String];
//SQLIte Statement
NSString *selettablequery = [NSString stringWithFormat:#"select * from MailBoxInfoDBTable"];
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
//if(sqlite3_prepare_v2(database, [selettablequery UTF8String], -1, &statement, NULL) == SQLITE_OK)
if (sqlite3_prepare(database, [selettablequery UTF8String], -1, &statement, NULL) ==SQLITE_OK)
{
// Take an array to store all string.
//NSMutableArray *allRows = [[NSMutableArray alloc] init];
while(sqlite3_step(statement) == SQLITE_ROW)
{
char *emailfield = (char *) sqlite3_column_text(statement, 0);
NSString *emailStr = [[NSString alloc] initWithUTF8String: emailfield];
NSLog(#"retrieveImapSessionForAccount: Email: %#", emailStr);
if([emailStr isEqualToString:emailAddress])
{
//const void *bytes = sqlite3_column_blob(statement, 3);
char *emailstring = (char *) sqlite3_column_text(statement, 3);
if (emailstring) {
NSString *messageStr = [[NSString alloc] initWithUTF8String: emailstring];
NSData *data = [[NSData alloc] initWithBase64EncodedString:messageStr options:NSDataBase64DecodingIgnoreUnknownCharacters];
imapsessionObj = [NSKeyedUnarchiver unarchiveObjectWithData:data];
}
}
}
}
sqlite3_finalize(statement);
sqlite3_close(database);
}
return imapsessionObj;
}
I got crash encodeWithCoder unrecognized selector sent to instance when doing NSKeyedArchiver archivedDataWithRootObject:imapSession
Then, I added the below methods in the 3rd party class MCOIMAPSession.mm file
- (void)encodeWithCoder:(NSCoder *)aCoder{
[aCoder encodeObject:self forKey:#"PROPERTY_KEY"];
}
-(id)initWithCoder:(NSCoder *)aDecoder{
if(self = [super init]){
self = [aDecoder decodeObjectForKey:#"PROPERTY_KEY"];
}
return self;
}
UPDATED: I tried the below as well.
#interface MCOIMAPSession : NSObject
....
#end
#interface NSObject (NSCoding)
-(id)initWithCoder:(NSCoder*)decoder;
-(void)encodeWithCoder:(NSCoder*)encoder;
#end
#endif
#implementation MCOIMAPSession
-(id)initWithCoder:(NSCoder *)decoder {
if ((self=[super initWithCoder:decoder])) {
}
return self;
}
#end
#implementation NSObject (NSCoding)
-(id)initWithCoder:(NSCoder*)decoder {
return [self init];
}
-(void)encodeWithCoder:(NSCoder*)encoder {}
#end
HERE IS THE FILE OF MCOIMAPSESSION MCOIMAPSESSION link .. Please let me know how can i add property now?
But, I see still the same crash. Could someone correct me what i'm doing wrong here when storing custom class MCOIMAPSession object in sqlite database?

Answer 1

Your implementation of the NSCoding methods is incorrect. You don't encode/decode self, you encode/decode each property/ivar of self. Something like:
- (void)encodeWithCoder:(NSCoder *)aCoder{
// Replace the following with the class's actual properties
[aCoder encodeObject:self.propertyA forKey:#"propertyA"];
[aCoder encodeObject:self.propertyB forKey:#"propertyB"];
[aCoder encodeObject:self.propertyC forKey:#"propertyC"];
}
-(id)initWithCoder:(NSCoder *)aDecoder{
if(self = [super init]){
// Replace the following with the class's actual properties
_propertyA = [aDecoder decodeObjectForKey:#"propertyA"];
_propertyB = [aDecoder decodeObjectForKey:#"propertyB"];
_propertyC = [aDecoder decodeObjectForKey:#"propertyC"];
}
return self;
}
BTW - your question has nothing at all to do with SQLite. Your question should be narrowed down just to the problem with the encoding/decoding.

Answer 2

You cannot call encodeWithCoder with object self. You have to encode (and decode) each relevant property of the class MCOIMAPSession.
Edit:
For the MCOIMAPSession the NSCoding methods should look like
- (id)initWithCoder:(NSCoder *)decoder
{
self = [super initWithCoder:decoder]
if (self) {
self.hostname = [decoder decodeObjectForKey:#"hostname"];
self.port = [decoder decodeIntegerForKey:#"port"];
self.username = [decoder decodeObjectForKey:#"username"];
self.password = [decoder decodeObjectForKey:#"password"];
// etc
}
return self;
}
-(void)encodeWithCoder:(NSCoder*)encoder
{
[aCoder encodeObject:self.hostname forKey:#"hostname"];
[aCoder encodeInteger:self.port forKey:#"port"];
[aCoder encodeObject:self.username forKey:#"username"];
[aCoder encodeObject:self.password forKey:#"password"];
// etc
}
Add all properties you need. And consider that properties representing instances of other custom classes must be also NSCoding compliant.