Changes in appearance is not applying until pushViewController - iphone

Question

I want to build object and then open a controller with it. Building can take up to 5 seconds and I want to show a message while it processing.
I have the following implementation of didSelectRowAtIndexPath:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
messageView.hidden = NO;
// Some methods
Controller *ctrl = [Controller new];
[self.navigationController pushViewController:ctrl animated:YES];
}
Everything is good but there is a problem: messageView appears ONLY when push animation starts. What can I do to fix that?

Answer 1

Similar to Jonathan's answer, delay the push a little to give the messageView time to appear.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
messageView.hidden = NO;
int64_t oneMillisecond = NSEC_PER_MSEC;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, oneMillisecond), dispatch_get_main_queue(), ^(void){
// Some methods
Controller *ctrl = [Controller new];
[self.navigationController pushViewController:ctrl animated:YES];
});
}

Answer 2

It's not displaying because you're blocking the main thread while building the object.
The user interface will not update until you return control to the run loop.
The solution is to build your object on a background thread, the easiest way of doing this is with libdispatch, like so:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
messageView.hidden = NO;
// you may want to disable user interaction while background operations happen
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
// Perform your lengthy operations here
Controller *ctrl = [[Controller alloc] init];
dispatch_async(dispatch_get_main_queue(), ^{
[self.navigationController pushViewController:ctrl animated:YES];
}
});
}

Answer 3

If you want a UIAlertView you can use this code:
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Title..." message:#"More?" delegate:nil cancelButtonTitle:nil otherButtonTitles:nil];
[alert show];
After your done you can call this to dismiss:
[alert dismissWithClickedButtonIndex:0 animated:YES];

Answer 4

Can you try with this:
[UIView animateWithDuration:0.5f delay:0.0f options:UIViewAnimationCurveLinear animations:^(void)
{
messageView.hidden = NO;
}
completion:^(BOOL finished)
{
Controller *ctrl = [Controller new];
[self.navigationController pushViewController:ctrl animated:YES];
}];

Answer 5

The view probably isn't redrawn during your didSelectRowAtIndexPath call.
So... I would try running the long running method in a block. Then block the main thread with you messageView animation and have your block post a notification or something to shut it down.
You might want to have some kind of condition for the messageView to shut itself down after a certain time.