Question

我正在使用CoreData来存储数据。我正在使用NSNumber的数据类型存储ContactNumber。我正在从DB中检索数据

  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)))

                }

但我的问题是我将ContactNumber视为“-27790.000000”。我试图将NSNumber转换为String但它对我不起作用。

 let s:String = String(format:"%f",  test.valueForKey("contactnumber")!.doubleValue)

print(s) - output:  “-27790.000000”

谁能告诉我我在做什么错误。

ThanksIn Advance

Answer 1

请勿使用String(format:...)。使用NSNumberFormatter：

let f = NSNumberFormatter()
f.maximumFractionDigits = 0
let s = f.stringFromNumber(-27790.00)!
print(s) // Output "-27790"

Answer 2

Swift 4.0 iOS 11.x

将NSNumber转换为字符串...

let temp:NSNumber = 5
let tempString = temp.stringValue

在swift中将NSNumber转换为String时出错

2 个答案: