Question

I’m using a UITableView control to show some data that can be edited by the user. To edit the details the user taps on an edit button which pushes a new view onto the stack. The user edits the data, taps a save button and the data is saved to a plist and the view popped off the stack. Even though the plist has been updated the UITableView still shows the old data. This can be corrected by adding a call to reloadData in the viewWillAppear method. However when the view is first loaded the data is displayed correctly, by adding the reload statement does this mean a double bind? If so, how can this be avoided?

I found the following code (here) which forces a refresh without explicitly calling reloadData:

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

Can anyone explain how/why this works?

Answer 1

The trick from your link is a dirty hack. Not only does it reload the data, but also forces the table to redraw. It tells your app that the device is getting a new orientation, so your table gets redrawn, along with other UI elements.

The standard way of refreshing a single row or a specific set of rows in your UITableView is calling its reloadRowsAtIndexPaths:withRowAnimation: method: doing so calls through to your data source to get data for only the row(s) that have been updated, preventing the full reload.