Swift:无法将类型 '[String : DayData]' 的值转换为预期的参数类型 'AnyObject?'

Question

我在尝试保存我创建的新结构时无法保存到 CoreData。

var allInformationByDate = [
"2016-08-13": DayData(sales: 0, doorsKnocked: 0, milesWalked: 0.00, hoursWorked: 0.00)

]

struct DayData { 
let sales: Int
let doorsKnocked: Int
let milesWalked: Double
let hoursWorked: Double
}

我收到错误:

Cannot convert value of type '[String : DayData]' to expected argument type 'AnyObject?'

关于这段代码，特别是关于“allInformationByDate”...

var allInfoByDateDefault = NSUserDefaults.standardUserDefaults()
    allInfoByDateDefault.setValue(allInformationByDate, forKey:"allInfoByDateRecord")
    allInfoByDateDefault.synchronize()

有人知道如何修正这个语法吗？我试过改成

allInformationByDate as! AnyObject

但这只会让应用程序崩溃。

Answer 1

问题是您无法在 NSUserDefaults 中保存自定义对象

但由于 DayData 的所有属性都符合属性列表，您可以编写 NSUserDefaults 的扩展以将 DayData 转换为字典，反之亦然.

此扩展可以编写单个 DayData 对象以及字典 [String:DayData]。

extension NSUserDefaults {

 // read a write a single 'DayData' object

  func dayDataForKey(key: String) -> DayData? {
    guard let data = self.objectForKey(key) as? [String:AnyObject] else { return nil }
    return DayData(sales: data["sales"] as! Int, doorsKnocked: data["doorsKnocked"] as! Int, milesWalked: data["milesWalked"] as! Double, hoursWorked: data["hoursWorked"] as! Double)
  }

  func setDayData(dayData : DayData, forKey key: String) {
    let propertyListRepresentation  = ["sales": dayData.sales, "doorsKnocked" : dayData.doorsKnocked, "milesWalked": dayData.milesWalked, "hoursWorked": dayData.hoursWorked]
    self.setObject(propertyListRepresentation, forKey: key)
  }

  // read a write a dictionary ('[String:DayData]') object

  func dayDataDictionaryForKey(key: String) -> [String: DayData]? {
    guard let dayData = self.objectForKey(key) as? [String : [String: AnyObject]] else { return nil }
    var result = [String: DayData]()
    for (key, value) in dayData {
      result[key] = DayData(sales: value["sales"] as! Int, doorsKnocked: value["doorsKnocked"] as! Int, milesWalked: value["milesWalked"] as! Double, hoursWorked: value["hoursWorked"] as! Double)
    }
    return result
  }

  func setDayDataDictionary(dayData : [String: DayData], forKey key: String) {
    var result = [String : [String: AnyObject]]()
    for (key, value) in dayData {
      result[key] = ["sales": value.sales, "doorsKnocked" : value.doorsKnocked, "milesWalked": value.milesWalked, "hoursWorked": value.hoursWorked]
    }
    self.setObject(result, forKey: key)
  }
}

现在您可以轻松地为用户默认值编写字典:

let defaults = NSUserDefaults.standardUserDefaults()
defaults.setDayDataDictionary(allInformationByDate, forKey: "allInfoByDateRecord")

或阅读它

let defaults = NSUserDefaults.standardUserDefaults()
if let infoByDateDefault = defaults.dayDataDictionaryForKey("allInfoByDateRecord") {
   allInformationByDate = infoByDateDefault
}