Dynamic TableHeaderView Height

gistfile1.m

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.label = [[UILabel alloc] initWithFrame:CGRectZero];
    self.label.translatesAutoresizingMaskIntoConstraints = NO;
    self.label.backgroundColor = [UIColor redColor];
    self.label.textAlignment = NSTextAlignmentCenter;
    self.label.numberOfLines = 0;
    self.label.text = @"Valerio adjkashdjk asdjk asd adj aklsdjasl dkjasdkl askldj aklsdj aklsddj aklsdj aklsdjaklsdj aklsdj aklsd Tiziano.";
    
    self.tableView.tableHeaderView = self.label;
    
    // Simulate text change
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        self.label.text = @"Valerio";
        [self.view setNeedsLayout];
    });
}

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];
    
    CGSize size = [self.label systemLayoutSizeFittingSize:CGSizeMake(CGRectGetWidth(self.view.bounds), 0)];
    
    // Avoid precision error
    if (fabs(size.height - self.label.frame.size.height) > FLT_EPSILON) {
        
        self.label.frame = CGRectMake(0, 0, 0, size.height);
        
        self.tableView.tableHeaderView = nil;
        self.tableView.tableHeaderView = self.label;
    }
}