What should I replace this code with?

Question

I recently got an example of some code from a friend but he told me one line needs to be changed to make it work for me. Here's the code:

- (void)tableView:(NSTableView *)aTableView willDisplayCell:(id)aCell forTableColumn:

(NSTableColumn *)aTableColumn row:(int)rowIndex {

    if ([aCell respondsToSelector:@selector(setTextColor:)]) {

     if ([self visibilityForFile:[fileList objectAtIndex:rowIndex]] == NO) 

[aCell setTextColor:[NSColor lightGrayColor]];

     else [aCell setTextColor:[NSColor blackColor]];
    }
}

I need to replace this line:

[self visibilityForFile:[fileList objectAtIndex:rowIndex]] == NO

With some different code, what I am actually trying to do is, as I've got a table every row in the table has a checkbox, when a checkbox in a row is checked the text color of that row will change. I think the code needs to check to see if the checkbox in the row is checked, I just need the code for that. Thanks.

Update

This is the Delegate for The App (Core Data).

Header File (.h):

#import <Cocoa/Cocoa.h>

@interface Spark_AppDelegate : NSObject 
{
    IBOutlet NSWindow *window;
    IBOutlet NSMenu *theMenu;

    NSPersistentStoreCoordinator *persistentStoreCoordinator;
    NSManagedObjectModel *managedObjectModel;
    NSManagedObjectContext *managedObjectContext;
}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator;
- (NSManagedObjectModel *)managedObjectModel;
- (NSManagedObjectContext *)managedObjectContext;

- (IBAction)saveAction:sender;

@end

.M file

/**
    Returns the support folder for the application, used to store the Core Data
    store file.  This code uses a folder named "Spark" for
    the content, either in the NSApplicationSupportDirectory location or (if the
    former cannot be found), the system's temporary directory.
 */

- (NSString *)applicationSupportFolder {

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES);
    NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : NSTemporaryDirectory();
    return [basePath stringByAppendingPathComponent:@"Spark"];
}


/**
    Creates, retains, and returns the managed object model for the application 
    by merging all of the models found in the application bundle.
 */

- (NSManagedObjectModel *)managedObjectModel {

    if (managedObjectModel != nil) {
        return managedObjectModel;
    }

    managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain];    
    return managedObjectModel;
}


/**
    Returns the persistent store coordinator for the application.  This 
    implementation will create and return a coordinator, having added the 
    store for the application to it.  (The folder for the store is created, 
    if necessary.)
 */

- (NSPersistentStoreCoordinator *) persistentStoreCoordinator {

    if (persistentStoreCoordinator != nil) {
        return persistentStoreCoordinator;
    }

    NSFileManager *fileManager;
    NSString *applicationSupportFolder = nil;
    NSURL *url;
    NSError *error;

    fileManager = [NSFileManager defaultManager];
    applicationSupportFolder = [self applicationSupportFolder];
    if ( ![fileManager fileExistsAtPath:applicationSupportFolder isDirectory:NULL] ) {
        [fileManager createDirectoryAtPath:applicationSupportFolder attributes:nil];
    }

    url = [NSURL fileURLWithPath: [applicationSupportFolder stringByAppendingPathComponent: @"Spark.xml"]];
    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];
    if (![persistentStoreCoordinator addPersistentStoreWithType:NSXMLStoreType configuration:nil URL:url options:nil error:&error]){
        [[NSApplication sharedApplication] presentError:error];
    }    

    return persistentStoreCoordinator;
}


/**
    Returns the managed object context for the application (which is already
    bound to the persistent store coordinator for the application.) 
 */

- (NSManagedObjectContext *) managedObjectContext {

    if (managedObjectContext != nil) {
        return managedObjectContext;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (coordinator != nil) {
        managedObjectContext = [[NSManagedObjectContext alloc] init];
        [managedObjectContext setPersistentStoreCoordinator: coordinator];
    }

    return managedObjectContext;
}


/**
    Returns the NSUndoManager for the application.  In this case, the manager
    returned is that of the managed object context for the application.
 */

- (NSUndoManager *)windowWillReturnUndoManager:(NSWindow *)window {
    return [[self managedObjectContext] undoManager];
}


/**
    Performs the save action for the application, which is to send the save:
    message to the application's managed object context.  Any encountered errors
    are presented to the user.
 */

- (IBAction) saveAction:(id)sender {

    NSError *error = nil;
    if (![[self managedObjectContext] save:&error]) {
        [[NSApplication sharedApplication] presentError:error];
    }
}


/**
    Implementation of the applicationShouldTerminate: method, used here to
    handle the saving of changes in the application managed object context
    before the application terminates.
 */

- (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender {

    NSError *error;
    int reply = NSTerminateNow;

    if (managedObjectContext != nil) {
        if ([managedObjectContext commitEditing]) {
            if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {

                // This error handling simply presents error information in a panel with an 
                // "Ok" button, which does not include any attempt at error recovery (meaning, 
                // attempting to fix the error.)  As a result, this implementation will 
                // present the information to the user and then follow up with a panel asking 
                // if the user wishes to "Quit Anyway", without saving the changes.

                // Typically, this process should be altered to include application-specific 
                // recovery steps.  

                BOOL errorResult = [[NSApplication sharedApplication] presentError:error];

                if (errorResult == YES) {
                    reply = NSTerminateCancel;
                } 

                else {

                    int alertReturn = NSRunAlertPanel(nil, @"There Are Un-Saved Changes. Quit anyway?" , @"Quit anyway", @"Cancel", nil);
                    if (alertReturn == NSAlertAlternateReturn) {
                        reply = NSTerminateCancel;  
                    }
                }
            }
        } 

        else {
            reply = NSTerminateCancel;
        }
    }

    return reply;
}


/**
    Implementation of dealloc, to release the retained variables.
 */

- (void) dealloc {

    [managedObjectContext release], managedObjectContext = nil;
    [persistentStoreCoordinator release], persistentStoreCoordinator = nil;
    [managedObjectModel release], managedObjectModel = nil;
    [super dealloc];
}


@end

Answer 1

What does [self visibilityForFile:] return? If it is not a BOOL, then you need to change it to something that does return a BOOL. Why don't you ask your friend what you're supposed to change the line to?

Answer 2

You need to change the if statement to read the boolean value backing the checkbox for the given row from your model. Since you didn't include any information about your model, no-one is going to be able to give you an actual line of code to use.

It's also not clear that the rest of the code will do what you want; it's changing the color of the text conditionally, not the row itself.

Answer 3

Generally, you do not want to base the display of one cell on the value of another one. A more MVC-compliant approach is to have the checkbox control a property of that row's object (say, isActive), which you can then check against in your code above to decide how to draw the text. As long as the checkbox state and the text color are both based on the same property, they'll match up as you want.

Also, the color you want is not [NSColor lightGrayColor], but rather [NSColor disabledControlTextColor]. And usually, you just want to disable the whole cell, i.e [aCell setEnabled:NO] instead of just changing the text color, which makes it act like a disabled cell as well as look like one.