Load more at the top of uitableview - iphone

Question

I need a load more cell at the top of my table populated with custom cell, the first time that I populate the table is all ok, no overlap and no problem, if I try to load more cell this cell appear but with the wrong height and if I try to scroll the cell change position randomly!
This is my code, where the mistake for you?
- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [self.arrayMessaggi count] + 1;
}
- (UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (indexPath.row == 0) {
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
UILabel *labelLoad = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
[labelLoad setBackgroundColor:[UIColor clearColor]];
[labelLoad setTextAlignment:NSTextAlignmentCenter];
[labelLoad setText:[NSString stringWithFormat:#"%d - Load more...",indexPath.row]];
[labelLoad setText:#"Load more..."];
[labelLoad setTag:3];
[cell.contentView addSubview:labelLoad];
}
UILabel *labelLoad = (UILabel *)[cell.contentView viewWithTag:3];
[labelLoad setText:[NSString stringWithFormat:#"%d - Load more...",indexPath.row]];
}
else {
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
PFObject *obj = [self.arrayMessaggi objectAtIndex:indexPath.row - 1];
PFUser *user = [obj objectForKey:#"daUtente"];
float height = [self getStringHeight:[obj objectForKey:#"TestoMessaggio"] andFont:[UIFont systemFontOfSize:13]];
UILabel *labelUser = [[UILabel alloc] initWithFrame:CGRectMake(20, 10, 280, 20)];
[labelUser setBackgroundColor:[UIColor clearColor]];
[labelUser setText:[user objectForKey:#"username"]];
[labelUser setFont:[UIFont systemFontOfSize:13]];
[labelUser setTag:1];
[cell.contentView addSubview:labelUser];
}
PFObject *obj = [self.arrayMessaggi objectAtIndex:indexPath.row - 1];
PFUser *user = [obj objectForKey:#"daUtente"];
UILabel *labelUser = (UILabel *)[cell.contentView viewWithTag:1];
[labelUser setText:[NSString stringWithFormat:#"%d - %#",indexPath.row,[user objectForKey:#"username"]]];
}
return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
float height = 44;
if (indexPath.row > 0) {
PFObject *obj = [self.arrayMessaggi objectAtIndex:indexPath.row - 1];
NSString *text = [obj objectForKey:#"TestoMessaggio"];
height = 30 + [self getStringHeight:text andFont:[UIFont systemFontOfSize:13]] + 10;
}
return height;
}
- (void) setPullDownToRefresh {
refreshControl = [[UIRefreshControl alloc] init];
[refreshControl addTarget:self action:#selector(aggiornaTabella:) forControlEvents:UIControlEventValueChanged];
[self.messagesTableView addSubview:refreshControl];
}
- (void) aggiornaTabella:(UIRefreshControl *)myRefreshControl {
self.arrayMessaggi = [NSMutableArray arrayWithArray:objects];
self.messagesTableView = [[UITableView alloc] init];
[self.messagesTableView reload data];
}