Optimization headers for UITableView?
- by Pask
I have an optimization problem for the headers of a table with plain style. If I use the standard view for the table (the classic gray with titles set by titleForHeaderInSection:) everything is ok and the scrolling is smooth and immediate.
When, instead, use this code to set my personal view:
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
return [self headerPerTitolo:[titoliSezioni objectAtIndex:section]];
}
- (UIImageView *)headerPerTitolo:(NSString *)titolo {
UIImageView *headerView = [[[UIImageView alloc] initWithFrame:CGRectMake(10.0, 0.0, 320.0, 44.0)] autorelease];
headerView.image = [UIImage imageNamed:kNomeImmagineHeader];
headerView.alpha = kAlphaSezioniTablePlain;
UILabel * headerLabel = [[[UILabel alloc] initWithFrame:CGRectZero] autorelease];
headerLabel.backgroundColor = [UIColor clearColor];
headerLabel.opaque = NO;
headerLabel.textColor = [UIColor whiteColor];
headerLabel.font = [UIFont boldSystemFontOfSize:16];
headerLabel.frame = CGRectMake(10.0,-11.0, 320.0, 44.0);
headerLabel.textAlignment = UITextAlignmentLeft;
headerLabel.text = titolo;
[headerView addSubview:headerLabel];
return headerView;
}
scrolling is jerky and not immediate (sliding the finger on the screen does not match an immediate shift of the table).
I do not know what caused this problem, maybe the fact that every time the method viewForHeaderInSection: is called, the code runs to create a new UIImageView.
I tried many ways to solve the problem, such as creating an array of all the necessary view: apart from more time spent loading at startup, there is a continuing problem of low reactivity of the table.
've Attempted by reducing the size of UIImageView positioned from about 66 KB to 4 KB: not only has a deterioration in quality of colors (which distorts a bit 'original graphics), but ... the problem persists!
Perhaps you have suggestions about it, or know me obscure techniques that enable me to optimize this aspect of my application ...
I apologize for my English, I used Google for translation.
