Question

I have a UISwitch inside a custom UITableViewCell (the subclass of which I call RootLabeledSwitchTableCell).

The cell contains a UILabel and UISwitch next to each other.

I have a @property called keychainSwitch that points to the switch inside this custom cell:

@interface RootLabeledSwitchTableCell : UITableViewCell {
    IBOutlet UILabel *textLabel;
    IBOutlet UISwitch *labeledSwitch;
}

@property (nonatomic, retain) IBOutlet UILabel *textLabel;
@property (nonatomic, retain) IBOutlet UISwitch *labeledSwitch;

@end

In my table view delegate, I have added a selector that is called if the switch state is flipped:

- (UITableViewCell *) tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath {
   NSString *CellIdentifier = [NSString stringWithFormat: @"%d:%d", [indexPath indexAtPosition:0], [indexPath indexAtPosition:1]];
   UITableViewCell *cell = [tv dequeueReusableCellWithIdentifier:CellIdentifier];
   if (cell == nil) {
       switch (indexPath.section) {
       case(kMyFirstSection): {
           switch (indexPath.row) {
               case(kMyFirstSectionFirstRow) {
                   [cellOwner loadMyNibFile:@"RootLabeledSwitchTableCell"];
                   cell = (RootLabeledSwitchTableCell *)cellOwner.cell;
                   self.keychainSwitch = [(RootLabeledSwitchTableCell *)cell labeledSwitch];
                   [self.keychainSwitch addTarget:self action:@selector(keychainOptionSwitched) forControlEvents:UIControlEventValueChanged];
                   break;
               }
               // ...
           }
       }
       // ...
   }
}

So this selector works correctly:

- (void) keychainOptionSwitched {
   NSLog(@"Switched keychain option from %d to %d", ![self.keychainSwitch isOn], [self.keychainSwitch isOn]);
}

However, I cannot use the UISwitch instance’s -setOn:animated: method to initialize its initial state:

- (void) updateInterfaceState {
   BOOL isFirstTimeRun = [[[NSUserDefaults standardUserDefaults] objectForKey:kIsFirstTimeRunKey] boolValue];
   if (isFirstTimeRun) {
      [self.keychainSwitch setOn:NO animated:NO];
   }
}

From testing, self.keychainSwitch is nil which is causing -setOn:animated to do nothing, but I can still operate the switch and the NSLog statement will correctly print the switch state changes, e.g.:

[Session started at 2009-08-24 07:04:56 -0700.]
2009-08-24 07:04:58.489 MyApp[29868:20b] keychain switch is: nil
2009-08-24 07:05:00.641 MyApp[29868:20b] Switched keychain option from 1 to 0
2009-08-24 07:05:01.536 MyApp[29868:20b] Switched keychain option from 0 to 1
2009-08-24 07:05:02.928 MyApp[29868:20b] Switched keychain option from 1 to 0

Is there something I am missing about setting self.keychainSwitch in the UITableView delegate method?

Answer 1

I did this a while ago.
You should change your selctor

[self.keychainSwitch addTarget:self action:@selector(keychainOptionSwitched:) forControlEvents:UIControlEventValueChanged];

And then update your method to

-(void) keychainOptionSwitched:(id)sender {
UISwitch *tempSwitch = (UISwitch *)sender;
}

Now tempSwitch is the switch that was changed.