How to delete all rows from table?

Normal SQL syntax to do this:

DELETE FROM tablename

SQLite Documentation. Deletion of rows in iOS :

NSString *query = @"delete from yourTable";
const char *sqlStatement = [query UTF8String];
sqlite3_stmt *compiledStatement;
if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) {
// Loop through the results and add them to the feeds array
while(sqlite3_step(compiledStatement) == SQLITE_ROW) {
    // Read the data from the result row
    NSLog(@"result is here");
}

// Release the compiled statement from memory
sqlite3_finalize(compiledStatement);

If you want to delete all rows from SQL table then go for

DELETE FROM tablename

If you want to delete rows one by one the go for

DELETE FROM tablename WHERE id=2

Change id as per your requirement or you can mention the specific field name also whose row you want to delete

(void) DeleteRows {


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

NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;
NSString *dbPath =[documentsDir stringByAppendingPathComponent:@"gym.db"];
BOOL success = [fileManager fileExistsAtPath:dbPath];
sqlite3_stmt *selectstmt;
if(!success)
{
    NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"gym.db"];
    success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];

    if (!success)
        NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
}

if (sqlite3_open([dbPath UTF8String], &contactDB) == SQLITE_OK) {
    //*************** insert value in database******************************\\

    NSString  *sql = [NSString stringWithFormat:@"delete from Offers"];
    const char *insert_stmt = [sql UTF8String];
    sqlite3_prepare_v2(contactDB,insert_stmt, -1, &selectstmt, NULL);
    if(sqlite3_step(selectstmt)==SQLITE_DONE)
    {
        NSLog(@"Delete successfully");
    }
    else
    {
        NSLog(@"Delete not successfully");

    }
    sqlite3_finalize(selectstmt);
    sqlite3_close(contactDB);
  }
}

- (IBAction)deleteAll:(id)sender { 

   NSString *tableName=@"Contacts";
   NSString *qsql = [NSString stringWithFormat:@"DELETE FROM %@",
                      tableName];
   sqlite3_stmt *statement;
    if (sqlite3_prepare_v2( db, [qsql UTF8String], -1,
                           &statement, NULL) == SQLITE_OK)
        while (sqlite3_step(statement) == SQLITE_DONE){
                        NSLog(@"%@", @"deleted");
        }
    else {
    sqlite3_close(db);
    NSAssert(0, @"Failed to Delete");
    }
   sqlite3_finalize(statement);

  }

In Swift you can do it like this:

let tableName = "myTable"
let deleteStatementString = "DELETE FROM \(tableName);"
var deleteStatement: OpaquePointer? = nil
if sqlite3_prepare_v2(db, deleteStatementString, -1, &deleteStatement, nil) == SQLITE_OK {
    if sqlite3_step(deleteStatement) == SQLITE_DONE {
        print("Successfully deleted all rowns from \(tableName)")
    } else {
        print("Could not delete all rowns from \(tableName)")
    }
} else {
    print("DELETE statement could not be prepared")
}
sqlite3_finalize(deleteStatement)