Question

I am using this code that “simulates” a dropdown menu as it works in html code. I have added 2 dropdown menus on my page. When I select an item in the first dropdown menu then my controller needs to be notified and the selected id from the selected dropdown item needs to be given in this notification. How can I notify my controller whenever an item has been selected in the first dropdown ? And also how do I package the notication with the selected id from the first dropdown list?

I initialize a dropdown using the below code:

ddDuration = [[UIDropDownMenu alloc] init];
[ddDuration makeMenu:txtDurationId titleArray:arrDurationIds valueArray: arrDurationNames targetView:self.view];
[ddDuration setDropdownTextColor:[UIColor whiteColor]];
[ddDuration setDropdownBackgroundColor:[UIColor darkGrayColor]];

The arrDurationsId and arrDurationNames contains the same number of elements. The first contains the ids and the latter the names.

Then I want the method below to be called whenever an item gets selected in dropdown 1. The sender needs to contain the selected item id from dropdown 1 – in order for dropdown 2 to know which content should be loaded into it.

- (IBAction)didSelectCountry:(id)sender {
    [ddDestination makeMenu:txtDestinationId titleArray:arrDepartureIds valueArray: arrDepartureNames targetView:self.view];
    [ddDestination setDropdownTextColor:[UIColor whiteColor]];
    [ddDestination setDropdownBackgroundColor:[UIColor darkGrayColor]];
}

Answer 1

You has the solution in the same page from where you download the code. Check this

[menu1 addObserver:self forKeyPath:@"selectedValue" options:NSKeyValueObservingOptionNew context:@"menu1"];

and this

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change (NSDictionary *)change context:(NSString *)context
{
    // get the selected menu and value
    NSString* changedObject = context;
    NSString* changedValue = [change objectForKey:NSKeyValueChangeNewKey];

    NSLog(@"%@ has changed to %@", changedObject, changedValue);

    // Menu 1 selected
    if ([context isEqualToString:@"menu1"]){
        // create a new array for menu 2.  
        NSArray *arrayNames2 = [[NSArray alloc] initWithObjects:
                        @"Erik Vanderwal",
                        @"Max Town",  
                        @"Avis Villalon",
                        @"Hugh Salvia",
                        nil];

        // rebuild menu 2 with the new array values
        [menu2 makeMenu:textfield2 titleArray:arrayNames2 valueArray: arrayNames2 targetView:self.view];

        // run makemenu with nil array values to clear the old values from menu 3
        [menu3 makeMenu:textfield3 titleArray:nil valueArray: nil targetView:self.view];

    }

    // Menu 2 selected
    if ([context isEqualToString:@"menu2"]){
        NSArray *arrayNames3 = [[NSArray alloc] initWithObjects:
                            @"Erik Vanderwal",
                            @"Hugh Salvia",
                            nil];

        [menu3 makeMenu:textfield3 titleArray:arrayNames3 valueArray: arrayNames3 targetView:self.view];

    }


}