NSPopupButton in view based NSTableView: getting bindings to work

Question

Problem Description

I\'m trying to achieve something that should be simple and fairly common: having a bindings populated NSPopupButton inside bindings populated NSTab

Answer 1

I always prefer the programmatic approach. Create a category on NSTableCellView:

+(instancetype)tableCellPopUpButton:(NSPopUpButton **)popUpButton
                         identifier:(NSString *)identifier
                    arrayController:(id)arrayController
                       relationship:(NSString *)relationshipName
        relationshipArrayController:(NSArrayController *)relationshipArrayController
              relationshipAttribute:(NSString *)relationshipAttribute
      relationshipAttributeIsScalar:(BOOL)relationshipAttributeIsScalar
                  valueTransformers:(NSDictionary *)valueTransformers
{
    NSTableCellView *newInstance = [[self alloc] init];
    newInstance.identifier = identifier;
    
    NSPopUpButton *aPopUpButton = [[NSPopUpButton alloc] init];
    aPopUpButton.autoresizingMask = NSViewWidthSizable | NSViewHeightSizable;
    
    [aPopUpButton bind:NSContentBinding  //the collection of objects in the pop-up
        toObject:relationshipArrayController
     withKeyPath:@"arrangedObjects"
         options:nil];
     
    NSMutableDictionary *contentBindingOptions = [NSMutableDictionary dictionaryWithDictionary:[[TBBindingOptions class] contentBindingOptionsWithRelationshipName:relationshipName]];
    
    NSValueTransformer *aTransformer = [valueTransformers objectForKey:NSValueTransformerNameBindingOption];
    if (aTransformer) {
        [contentBindingOptions setObject:aTransformer forKey:NSValueTransformerNameBindingOption];
    }
    [aPopUpButton bind:NSContentValuesBinding // the labels of the objects in the pop-up
        toObject:relationshipArrayController
     withKeyPath:[NSString stringWithFormat:@"arrangedObjects.%@", relationshipAttribute]
         options:[self contentBindingOptionsWithRelationshipName:relationshipName]];
    
    NSMutableDictionary *valueBindingOptions = [NSMutableDictionary dictionaryWithObjectsAndKeys:
        [NSNumber numberWithBool:YES], NSAllowsEditingMultipleValuesSelectionBindingOption,
        [NSNumber numberWithBool:YES], NSConditionallySetsEditableBindingOption,
        [NSNumber numberWithBool:YES], NSCreatesSortDescriptorBindingOption,
        [NSNumber numberWithBool:YES], NSRaisesForNotApplicableKeysBindingOption,
        [NSNumber numberWithBool:YES], NSValidatesImmediatelyBindingOption,
        nil];;
    
    @try {
        // The object that the pop-up should use as the selected item
        if (relationshipAttributeIsScalar) {
            [aPopUpButton bind:NSSelectedValueBinding
                toObject:newInstance
             withKeyPath:[NSString stringWithFormat:@"objectValue.%@", relationshipName]
                 options:valueBindingOptions];
        } else {
            [aPopUpButton bind:NSSelectedObjectBinding
                toObject:newInstance
             withKeyPath:[NSString stringWithFormat:@"objectValue.%@", relationshipName]
                 options:valueBindingOptions];
        }
    }
    @catch (NSException *exception) {
        //NSLog(@"%@ %@ %@", [self class], NSStringFromSelector(_cmd), exception);
    }
    @finally {
        [newInstance addSubview:aPopUpButton];
        if (popUpButton != NULL) *popUpButton = aPopUpButton;
    }
    
    return newInstance;
}

+ (NSDictionary *)contentBindingOptionsWithRelationshipName:(NSString *)relationshipNameOrEmptyString
{
    NSString *nullPlaceholder;
    if([relationshipNameOrEmptyString isEqualToString:@""])
        nullPlaceholder = NSLocalizedString(@"(No value)", nil);
    else {
        NSString *formattedPlaceholder = [NSString stringWithFormat:@"(No %@)", relationshipNameOrEmptyString];
        nullPlaceholder = NSLocalizedString(formattedPlaceholder,
                                            nil);
    }
    
    return [NSDictionary dictionaryWithObjectsAndKeys:
            nullPlaceholder, NSNullPlaceholderBindingOption,
            [NSNumber numberWithBool:YES], NSInsertsNullPlaceholderBindingOption,
            [NSNumber numberWithBool:YES], NSRaisesForNotApplicableKeysBindingOption,
            nil];
}