Making your iPad app redraw a UITableView

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Apple HATES redrawing views.  They are so brutal they kill cells in a tableview when the leave the view.  That’s just mean. I mean a cell can’t take up that much memory can it?  There are a bunch of fun methods you can use to try and redraw a view in Cocoa Touch.  You can call

[self.view setNeedsDisplay];

[self.view setNeedsLayout];

or if you’re trying to reload a UITableView you can call

[yourTableView reloadData];

The problem with that method is that it only works on the table’s datasource.  If you want to actually redraw the table you’ll need to be a bit more creative.

The app I’m currently working on has two different views based on whether or not you’re in the landscape or portrait orientation.  We noticed a bunch of bugs that dealt with pushing/popping views on the stack in one orientation then changing orientation and navigating back.  The views always looked shitty until you changed orientation.

Here’s a little trick to force a reload.

Implement the viewWillAppear method in your view controller like so.  And from that method call your willRotateToInterfaceOrientation passing in your current UIDevice orientation.

- (void) viewWillAppear:(BOOL)animated
 {
 [super viewWillAppear:animated];
 int orientation = [[UIDevice currentDevice] orientation];
 if(orientation != UIDeviceOrientationUnknown)
   [self willRotateToInterfaceOrientation:orientation duration:0];
 }

This will force a redraw right before the view loads and will present your nice, shiny UI to your users.

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