Taking too much time to retrieve rows from SQLite - ios

Question

I am new to iOS. I am trying to implement a SQLite database.
My problem is that when I go to fetch data from database, it takes a lot of time even though there are only 50 records inside the tables.
I did make a separate method for fetching data because many times I need to retrieve data for different tables.
My method:
-(NSArray*)fetch_data:(NSString *)table_name fields_arr:(NSMutableArray *)fields_arr{
NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsDir = dirPaths[0];
databasePath = [[NSString alloc] initWithString:[docsDir stringByAppendingPathComponent: #"test.db"]];
const char *dbpath = [databasePath UTF8String];
if (sqlite3_open(dbpath, &database) == SQLITE_OK)
{
sqlite3_stmt *SelectStatement;
NSMutableDictionary *record_dict;
NSString *SelectQry=#"select ";
NSString *lastField = [fields_arr lastObject];
for (int i =0; i<[fields_arr count]; i++) {
if (fields_arr[i] == lastField) {
SelectQry = [SelectQry stringByAppendingString:[NSString stringWithFormat:#"%# ",fields_arr[i]]];
} else {
SelectQry = [SelectQry stringByAppendingString:[NSString stringWithFormat:#"%#,",fields_arr[i]]];
}
}
SelectQry = [SelectQry stringByAppendingString:[NSString stringWithFormat:#"from %#",table_name]];
const char *query_stmt = [SelectQry UTF8String];
NSMutableArray *resultArray = [[NSMutableArray alloc]init];
if (sqlite3_prepare_v2(database,
query_stmt, -1, &SelectStatement, NULL) == SQLITE_OK)
{
while(sqlite3_step(SelectStatement) == SQLITE_ROW)
{
record_dict=[[NSMutableDictionary alloc]init];
for (int i = 0; i<[fields_arr count]; i++) {
NSString *field_value = [[NSString alloc]init];
field_value = [[NSString alloc] initWithUTF8String:
(const char *) sqlite3_column_text(SelectStatement, i)];
[record_dict setValue:field_value forKey:fields_arr[i]];
}
[resultArray addObject:record_dict];
}
return resultArray;
//sqlite3_reset(statement);
sqlite3_finalize(SelectStatement);
}
else{
sqlite3_finalize(SelectStatement);
return nil;
}
}

Answer 1

In your code you are opening database connection for each time method is called for fetching data. This is not appropriate way. You must establish connection only once and use it.
+(sqlite3 *)openDatabase{
if (database == NULL) {
NSString* str_path=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *path = [str_path stringByAppendingPathComponent:strDatabaseName];
if (sqlite3_open([path UTF8String], &database) == SQLITE_OK) {
NSLog(#"Database Successfully Opened");
}
else {
NSLog(#"Error in opening database");
database = NULL;
}
}
return database;}
You can call this on app launch from app delegate and define this method in a class where you are defining other DB methods. I hope it will reduce some overhead and will reduce some time too.