Core-Data willSave: method

Question

I have an attribute modificationDate in my Entity A. I want to set its value whenever NSManagedObject is saved. However, if i try to d

Answer 1

Swift 4 solution which is a combination of zmit and Richard answer without the need of recurring to NSNotification:

override func willSave() {
    let expectedNewValue = "Your new value"
    if customField != expectedNewValue, changedValues()[#keyPath(Entity.customField)] == nil, !isDeleted {
        customField = expectedNewValue
    }
    super.willSave()
}