title: Getting error in conversion of NSNumber to String in swift
body: <p>I am using CoreData to store the data.I am storing ContactNumber with the datatype of NSNumber. I am retrieving the data from DB like </p>
  
  <pre><code>  let entityDescription =
              NSEntityDescription.entityForName("Retailer",
                  inManagedObjectContext: managedObjectContext)
  
              let request = NSFetchRequest()
              request.entity = entityDescription
  
              do{
                  let results = try managedObjectContext.executeFetchRequest(request)
  
  
                  for test in results
                  {
  
  
                      print(test.valueForKey("address") as? String)
                       print(test.valueForKey("classes") as? String)
                       print(test.valueForKey("contactnumber") as! NSNumber)
                       print(test.valueForKey("landmark") as? String)
                      print(test.valueForKey("name") as? String)
                      print(test.valueForKey("outlettype") as? String)
                      print(test.valueForKey("retailername") as? String)
                       print(test.valueForKey("type") as? String)
                      print(test.valueForKey("credit") as? String)
  
  
        self.arrayOfData.append((StoringClass(retailersname: (test.valueForKey("retailername") as? String)!, names: (test.valueForKey("name") as? String)!, outlettypes: (test.valueForKey("outlettype") as? String)!, types: (test.valueForKey("type") as? String)!, credits: (test.valueForKey("credit") as? String)!, landmarks: (test.valueForKey("landmark") as? String)!, classestype: (test.valueForKey("classes") as? String)!, addresses: (test.valueForKey("address") as? String)!, contactnumbers:s)))
  
                  }
  </code></pre>
  
  <p>But my problem is I am getting the ContactNumber as “-27790.000000” like that.
  I tried to convert the NSNumber to String but it doesn’t work for me.</p>
  
  <pre><code> let s:String = String(format:"%f",  test.valueForKey("contactnumber")!.doubleValue)
  
  print(s) - output:  “-27790.000000” 
  </code></pre>
  
  <p>Can anyone tell me what mistake I am doing.</p>
  
  <p>ThanksIn Advance</p>