Creating and Customizing the Identity Picker

For every Identity Picker your application requires, you should create a separate instance of the CBIdentityPicker class.

The ability of the Identity Picker to select multiple entries at once is a customizable feature. By default, the Identity Picker does not allow multiple selections. To change the default setting, call the setAllowsMultipleSelection: method and pass the value YES. See Listing 2-1 for an example of how to use these methods.

Listing 2-1  Customizing an CBIdentityPicker instance

// Instantiate an ABIdentityPicker object.

CBIdentityPicker *picker = [[CBIdentityPicker alloc] init];

// Allow the Identity Picker to select multiple entries.

[picker setAllowsMultipleSelection:YES];

Invoking the Identity Picker Sheet

The beginSheetModalForWindow:modalDelegate:didEndSelector:contextInfo: method invokes the Identity Picker as a sheet.

The first argument is the window in which the sheet should open. In most cases, this is [sender window]. The modalDelegate argument is the delegate object. The didEndSelector argument is the method that will be called when the user selects identities and chooses either the OK or Cancel button. It should be a method that contains three arguments of its own: a CBIdentityPicker object, a return code, and a context. Finally, the contextInfo argument is any object you want sent to the delegate method.

Listing 2-2  Invoking the Identity Picker sheet

- (IBAction)plusButton:(id)sender

{

    [picker beginSheetModalForWindow:[sender window]

            modalDelegate:self

            didEndSelector:@selector(identityPickerDidEnd:returnCode:contextInfo:)

            contextInfo:nil];

}

When the user closes the Identity Picker, the delegate method (identityPickerDidEnd:identities:contextInfo:) is called. This method passes the selected identities as an array of CBIdentity objects and the context defined by the method beginSheetModalForWindow:modalDelegate:didEndSelector:contextInfo:. See Listing 2-3.

Listing 2-3  Retrieving identities from the Identity Picker

- (void)identityPickerDidEnd:(CBIdentityPicker *)identityPickerController returnCode:(NSInteger)returnCode contextInfo:(void *)contextInfo

{

    NSEnumerator *enumerator = [[identityPickerController identities] objectEnumerator];

    CBIdentity *nextIdentity;

    while (nextIdentity = [enumerator nextObject]) {

        //Do something interesting with the nextIdentity object

    }

}

Invoking the Identity Picker Modal Dialog

To use the Identity Picker modal dialog, call the method runModal. This method invokes the modal identity picker. If the user selects the OK button in the Identity Picker window, you can return the selected identities with the identities method. The identities method returns an array of CBIdentity objects. See Listing 2-4.

Listing 2-4  Invoking the modal Identity Picker

- (IBAction)plusButton:(id)sender

{

    NSArray *identities;

    NSEnumerator *enumerator;

    CBIdentity *nextIdentity;

    if ([picker runModal] == NSOKButton) {

        identities = [picker identities];

        enumerator = [identities objectEnumerator];

        // Enumerate over the returned identities

        while ((nextIdentity = [enumerator nextObject])) {

            // Do something interesting with the identity object

        }

    }

}