ios - 无法从 .plist 为我的模型 (NSObject) 加载我的所有对象

Question

你好。

我在我的应用程序中创建了模型，其中有 ShoppingList 和 Items 类(NSObject)。
每个项目只有一个 ShoppingList 和 ShoppingList 有更多的项目

(购物 list <-->>商品)

我已经将所有数据作为 NSArray 和 NSDictionary 保存到 plist，但现在我在加载项目时遇到问题。

我的 list :

Root (NSArray)->>

___________Item 0(Dictionary)->>

________________________date(Date),name(String),items(Array)->> ____________________________________________________Item 0(Dictionary)->>
________________________________________________________________date(Date),name(String)

这是我编写和阅读此 plist 的代码:

- (NSDictionary *)propertyListRepresentation {
NSMutableArray *itemsAsPropertyLists = [NSMutableArray new];
for (Item *item in self.items) {
    NSDictionary *itemPropertyList = [item propertyListRepresentation];
    [itemsAsPropertyLists addObject:itemPropertyList];
}

return @{
         @"name": self.nameOfList ?: @"",
         @"date": self.date ?: [NSDate distantPast],
         @"items": itemsAsPropertyLists,
         };
}
+ (ShoppingList *)createFromPropertyListRepresentation:(NSDictionary *)plist {
ShoppingList *newList = [ShoppingList new];

newList.nameOfList = [plist objectForKey:@"name"];
newList.date = [plist objectForKey:@"date"];

return newList;
}
+ (NSArray *)loadPropertyList{
NSArray*loadData = [NSArray arrayWithContentsOfFile:@"/Users/Me/Desktop/saved.plist"];
NSMutableArray *shoppingLists = [NSMutableArray new];

for (NSDictionary *loadDictionary in loadData) {
     ShoppingList *shoppingList = [ShoppingList createFromPropertyListRepresentation:loadDictionary];
    [shoppingLists addObject:shoppingList];

     for (NSArray *array in loadDictionary) {
          NSArray *itemsArray = [NSArray new];
       itemsArray = [Item loadPropertyList:array];
       [shoppingLists addObject:itemsArray];
     }
}
return shoppingLists;

}

对于项目:

- (NSDictionary *)propertyListRepresentation {
return @{
         @"name": self.name ?: @" ",
        @"date" : self.date ?:[NSDate date],
         };
}
 +(Item*)createFromPropertyListRepresentation:(NSDictionary*)dict {
Item *newItems = [Item new];

newItems.name = [dict objectForKey:@"name"];
newItems.date = [dict objectForKey:@"date"];

return newItems;
}
+(NSArray*)loadPropertyList:(NSArray*)array {
NSMutableArray *listOfItems = [NSMutableArray new];
for (NSDictionary*dict in array) {
    Item *item = [Item createFromPropertyListRepresentation:dict];
    [listOfItems addObject:item];
    }

return listOfItems;
}

所以这个代码工作停止在线工作
Item *item = [Item createFromPropertyListRepresentation:dict];
出现错误:

-[__NSCFString countByEnumeratingWithState:objects:count:]: unrecognized selector sent to instance

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString countByEnumeratingWithState:objects:count:]: unrecognized selector sent to instance

感谢您的帮助。

Answer 1

NSDictionary 的 NSFastEnumeration 实现返回键，而不是对象。而不是 for (NSArray *array in loadDictionary)你应该按照以下方式做一些事情:

NSArray *itemPlist = [loadDictionary objectForKey: @"items"];
NSArray *items = [Item loadPropertyList: itemPlist];
[shoppingLists addObject: items];

但是您可能也想对名称和日期做一些事情。