How to set a core-data attibute to nil, in Swift?

Question

Here is a working Swift function I have:

func myColorFuntion (object:NSManagedObject) -> UIColor {
    if (object.valueForKey("bgColor") == nil) {return UIColor.yellowColor()}
    return NSKeyedUnarchiver.unarchiveObjectWithData(object.valueForKey("bgColor") as! NSData) as! UIColor
}

My question relates to the line with the “if” statement. object.valueForKey("bgColor") starts with a nil value because it has not been defined. I can set something not nil for object.valueForKey("bgColor") with code like the following and it works.

let theColorData:NSData = NSKeyedArchiver.archivedDataWithRootObject(UIColor.cyanColor())
var object:NSManagedObject
object.setValue(theColorData forKey:"bgColor")

But how can I set object.valueForKey("bgColor") back to nil? The few trials I made using nil and NSNull didn’t work.

`

Why not use transparent, or a default colour of your choosing instead of null? — App Dev Guy, Jun 08 '15 at 16:29
Also, what sort of object are you referring to here? A button, the background, a textview? — App Dev Guy, Jun 08 '15 at 16:32
What happened when you tried `object.setValue(nil, forKey:"bgColor")`? — Marcus S. Zarra, Jun 08 '15 at 20:35
Thanks, Marcus's answer works. I had tried before but failed because I was not doing it right. — Michel, Jun 09 '15 at 01:25

score 3 · Answer 1 · edited Sep 01 '20 at 11:39

3

In Swift 4, try:

object.setNilValueForKey("your attribute name")

edited Sep 01 '20 at 11:39

davidev

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answered Jan 24 '19 at 20:28

eGanges

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How to set a core-data attibute to nil, in Swift?

1 Answers1