如何在 swift 中读取数组和字典的 plist

Posted 2023-02-23

【中文标题】如何在 swift 中读取数组和字典的 plist

【英文标题】：How to read a plist of array and dictionary in swift

【发布时间】：2015-07-02 17:04:18

【问题描述】：

我正在关注 Apple 示例项目 TVAnimationsGestures，但将其应用于我自己的项目之一。我需要将数据从 plist 加载到我的类中，但我似乎无法弄清楚如何快速做到这一点。这是 plist 尝试读取的图像。

示例项目使用此方法读取plist

- (NSArray *)plays 

if (_plays == nil) 

    NSURL *url = [[NSBundle mainBundle] URLForResource:@"PlaysAndQuotations" withExtension:@"plist"];
    NSArray *playDictionariesArray = [[NSArray alloc ] initWithContentsOfURL:url];
    _plays = [NSMutableArray arrayWithCapacity:[playDictionariesArray count]];

    for (NSDictionary *playDictionary in playDictionariesArray) 

        APLPlay *play = [[APLPlay alloc] init];
        play.name = playDictionary[@"playName"];

        NSArray *quotationDictionaries = playDictionary[@"quotations"];
        NSMutableArray *quotations = [NSMutableArray arrayWithCapacity:[quotationDictionaries count]];

        for (NSDictionary *quotationDictionary in quotationDictionaries) 

            APLQuotation *quotation = [[APLQuotation alloc] init];
            [quotation setValuesForKeysWithDictionary:quotationDictionary];

            [quotations addObject:quotation];
        
        play.quotations = quotations;

        [_plays addObject:play];
    


return _plays;

我环顾四周并设法让大部分内容不显示任何错误，但我认为它没有正确完成，因为有很多演员表。这是我已经走了多远：

    func loadFoodCategoryData() ->[Any] 
    // foodCategoryData is declared outside the function
    if foodCategoryData == nil 

        var url = NSBundle.mainBundle().URLForResource("Items", withExtension: "plist")!
        var categoryDictionaryArray = NSArray(contentsOfURL: url) as! [[String:AnyObject!]]
        foodCategoryData = Array()

        for foodDictionary:Dictionary in categoryDictionaryArray 

            var foodCat = FoodCategories()
            foodCat.foodCategoryName = foodDictionary["categoryName"] as! String

            var foodItemsDict = foodDictionary["items"]
            var foodItemsArray = [AnyObject]()

            for foodItems in foodDictionary 

                var foodItem:FoodItems = FoodItems()
                foodItem.setValuesForKeysWithDictionary(foodItems as! Dictionary)

                foodItemsArray.append(foodItem)

            
        
    

    return foodCategoryData

谁有更好更有效的方法来将此 plist 加载到我的类中？

【问题讨论】：

你在函数之外声明foodCategoryData吗？你声明它是什么？

是的，是函数外的变量。

【参考方案1】：

惰性初始化变量在 Swift 中具有特定的语法。相当于ObjC的代码是（体简化）

  lazy var plays : [AnyObject] = 
    var foodCategoryData = [AnyObject]()
    // do things
    foodCategoryData.append("something")
    return foodCategoryData
  ()

从 AnyObject 向下转换是一种痛苦但必要的

编辑

您的代码非常接近。试试这个（未经测试）

lazy var foodCategoryData : [AnyObject] = 

  let url = NSBundle.mainBundle().URLForResource("Items", withExtension: "plist")!
  var categoryDictionaryArray = NSArray(contentsOfURL: url) as! [[String:AnyObject!]]
  var foodItemsArray = [FoodItems]()

  for foodDictionary in categoryDictionaryArray 

    var foodCat = FoodCategories()
    foodCat.foodCategoryName = foodDictionary["categoryName"] as! String

    var foodItemsDict = foodDictionary["items"] as! [String:AnyObject]


    for foodItems in foodDictionary 

      var foodItem:FoodItems = FoodItems()
      foodItem.setValuesForKeysWithDictionary(foodItems as! Dictionary)

      foodItemsArray.append(foodItem)

    
  
  return foodItemsArray
 ()

【讨论】：

我理解那部分。我不明白的是如何从我的 plist 中提取数据并将值设置到我的自定义类中。

谢谢，它在大多数情况下都有效。我在“foodItem.setValuesForKeysWithDictionary(foodItems as! Dictionary)”处收到警告，它说“从 (String,implicitlyUnwrappedOptional) 转换为不相关的类型 Dictionary 总是失败”