Coredata relationship issue

Question

I\'m facing a weird issue with my core data. I\'ve the following relationship

A contact can belong to one category and a category can have multiple contacts. I\'d like

Answer 1

The answer is in your error:

Cannot assign a value of type 'String!' to a value of type 'Category'

The error is saying, that your category property in Contact class is defined to hold Category type object rather than an instance of NSString.

So you need to assign an object of type Category, something like this:

Create new category, or get an existing category by any means, here we'll create new category and assign that to the contact.

let catEntity = NSEntityDescription.entityForName("Category", inManagedObjectContext: context!)
let category = Category(entity: catEntity!, insertIntoManagedObjectContext: context)
category.name = categoryField.text // get the name from field and set to category property
category.color = someColor //assign your required color

Now assign that to your category property in Contact, like this:

newContact.category = category

Answer 2

The category property of a Contact object is a Category object. But you are trying to set it to be a String (categoryField.text). You probably want to use a Category object whose name is equal to categoryField.text.

You could create one:

    let categoryEntity = NSEntityDescription.entityForName("Category", inManagedObjectContext: context!)
    let newCategory = Category(entity: categoryEntity!, insertIntoManagedObjectContext: context)
    newCategory.name = categoryField.text
    // set the other properties for the Category as necessary
    // then assign the relationship
    newContact.category = newCategory

But you might already have created a Category with that name. So the usual approach would be to search for a Category with the right name, use that if it exists, or create a new Category if not:

    let categoryEntity = NSEntityDescription.entityForName("Category", inManagedObjectContext: context!)
    let fetchRequest = NSFetchRequest()
    fetchRequest.entity = categoryEntity!
    fetchRequest.predicate = NSPredicate(format:"name == %@",categoryField.text)
    let fetchResults = try? context!.executeFetchRequest(fetchRequest)
    if let results = fetchResults {
        var requiredCategory : Category
        if (results.count > 0) {
            requiredCategory = results[0] as! Category
        } else {
            requiredCategory = Category(entity: categoryEntity!, insertIntoManagedObjectContext: context!)
            requiredCategory.name = categoryField.text
            // set the other properties for the Category as necessary
        }
        newContact.category = requiredCategory
    }