Change CPPickerview selection programmatically?

Question

So i have a switch and when it is "on" i would like the CPPickerView to switch to a particular value in an array. As well if the pickerview is moved again i would like the switch to move to the off position.

I know how to get the current day of the week and am trying to switch the pickerview selection to the current day of the week.

If i am way off base here asking such a generalised question just let me know or if you need any more information.

    //CPPicker
    self.daysOfWeekData = [[NSArray alloc] initWithObjects:@"Monday", @"Tuesday", @"Wednesday", @"Thursday", @"Friday", @"Saturday", @"Sunday", nil];
    self.dayPickerView.allowSlowDeceleration = YES;
    [self.dayPickerView reloadData];
#pragma mark - Horizontal pickerview

//DataSource
-(NSInteger)numberOfItemsInPickerView:(CPPickerView *)pickerView {
    return 7;
}

-(NSString *)pickerView:(CPPickerView *)pickerView titleForItem:(NSInteger)item {
    return daysOfWeekData[item];
}

//Delegate
-(void)pickerView:(CPPickerView *)pickerView didSelectItem:(NSInteger)item {
    self.dayLabel.text = [NSString stringWithFormat:@"%@", daysOfWeekData[item]];
}

//Today's day date
- (IBAction)todaySwitchChange:(id)sender {

    if (todaySwitch.on) {

         NSLog(@"It is on");

    } else {

        NSLog(@"It is off");

    }
}

Answer 1

This can be done by using CPPickerView's setSelectedItem:animated: method, along with the normal delegate methods.

In your todaySwitchChange: method when the switch is turned on, set the CPPickerView to your desired index:

//Today's day date
- (IBAction)todaySwitchChange:(id)sender {

    if (todaySwitch.on) {
        NSLog(@"It is on");

        // This will cause the CPPickerView to select the item you choose
        NSUInteger itemToSelect = someValue; //whatever logic you need to select the right index
        [self.dayPickerView setSelectedItem:itemToSelect animated:YES]; // Or disable animation if desired

    } else {

        NSLog(@"It is off");

    }
}

To toggle the switch off when the user scrolls on the CPPickerView, you'll need to hook into the delegate method which gives you notification that scrolling has occurred:

// Implement the following delegate method
- (void)pickerViewWillBeginChangingItem:(CPPickerView *)pickerView {
    // Picker is going to change due to user scrolling, so turn the switch off
    if (todaySwitch.on) {
        todaySwitch.on = NO;
    }
}

Hope this helps!