Question

有没有办法为NSUserDefaults中的同一个密钥保存多个值？我似乎只保存最后一个值，即使我有“Day”键的多个值。

Day：

for days in results! {
    let nD = DayClass()
    nD.dayOfTheWeek = days[“D”] as! String
    let defaults = NSUserDefaults.standardUserDefaults()
    defaults.setObject(nD.dayOfTheWeek, forKey: “Day”)
}

我尝试过创建一个数组作为一种可能的解决方案，但是当我在控制台中记录它时，我仍然只得到最后一个值：

var emptyArray = [String]()
emptyArray.append(dayOfTheWeek)
print("Array: \(emptyArray)")
print("ArrayCount: \(emptyArray.count)")

Answer 1

你可以这样做。首先检查prefs中是否已有Day数组。如果是这样，那么将新的dayOfTheWeek添加到该数组并存储它。否则创建一个新的并存储它。

for days in results! {
    let dayOfTheWeek = days["D"] as! String
    //check if there is already an existing Day array in prefs
    if var existingArr = NSUserDefaults.standardUserDefaults().arrayForKey("Day") as? [String] {
        //if so append the new value to that array and store it
        if existingArr.contains(dayOfTheWeek) == false {
            existingArr.append(dayOfTheWeek)
            let defaults = NSUserDefaults.standardUserDefaults()
            defaults.setObject(existingArr, forKey: "Day")
            defaults.synchronize()
        }
    } else {
        //create a new array and store it
        let defaults = NSUserDefaults.standardUserDefaults()
        defaults.setObject([dayOfTheWeek], forKey: "Day")
        defaults.synchronize()
    }
}

Answer 2

   var food: [String] 
                            {


   get {

        if let returnValue = 
NSUserDefaults.standardUserDefaults().objectForKey("food") as? [String] {
            return returnValue
        } else {
            return ["muesli", "banana"] //Default value
        }
    }
    set {
        NSUserDefaults.standardUserDefaults().setObject(newValue, forKey: "food")
        NSUserDefaults.standardUserDefaults().synchronize()
    }
}

override func viewDidLoad() {
    super.viewDidLoad()

    print(food) // prints: ["muesli", "banana"] (at first launch)

    food = ["cake"]
    print(food) // prints: ["cake"]

    food += ["spaghetti"]
    print(food) // prints: ["cake", "spaghetti"]

    food = []
    print(food) // prints: []

    NSUserDefaults.standardUserDefaults().setObject(nil, forKey: "food")
    print(food) // prints: ["muesli", "banana"]
}

Answer 3

let daysArray = ["Sat", "Sun", "Mon", "Tu", "Wed", "Th", "Fri"]
// Set Array Into NSUserDefaults
NSUserDefaults().setObject(daysArray, forKey: "day")

// Retrive Array from NSUserDefaults
if let daysOfWeek = NSUserDefaults().arrayForKey("day") as? [String] {
  for item in daysOfWeek {
    print(item)
  }
}

在NSUserDefaults键中保存多个值

3 个答案: