Delete an object from an array

Question

I have created two buttons (add and edit):

var addButton = UIBarButtonItem(title: "Add", style: .Plain, target: self, action: "tabBarAddClicked"); self.navigationItem.rightBarButtonItems = [self.editButtonItem(), addButton]

These also work and I can delete objects from the tableView with the function

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
   if editingStyle == UITableViewCellEditingStyle.Delete {
        subjects.removeAtIndex(indexPath.row)
        tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)
    }
}

Hereby:

var subjects: [Subject] = subjectsData

and

var subjectsData = [ Subject(name: "Investments", semester: 1), Subject(name: "Statistics", semester: 1), Subject(name: "Studium Universale", semester: 2) ]

Though, when I go back in the navigation bar to the previous screen and then return to the screen, the deleted objects from the array are again there. But I told it to remove the objects from the array subjectsData with subjects.removeAtIndex(indexPath.row).

Why do the objects return and how can I change that?

MirekE · Accepted Answer · 2015-08-11 23:11:01Z

1

But I told it to remove the objects from the array subjectsData with subjects.removeAtIndex(indexPath.row).

You told it to remove from subjects, not subjectsData.

For example:

var array1 = [1, 2, 3]
var array2 = array1


array2.removeFirst()

print(array1) // [1, 2, 3]
print(array2) // [2, 3]

answered Aug 11, 2015 at 23:11

MirekE

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2 Comments

Elina Over a year ago

But is subjects not subjectsDatabecause of var subjects: [Subject] = subjectsData?

Elina Over a year ago

If I change the code to subjectsData.removeAtIndex(indexPath.row), the app crashes with the error: "Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (4) must be equal to the number of rows contained in that section before the update (4), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'"

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