Ambiguous use of 'subscript'

Question

Created May ’17

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Hello, I'm trying to read data from a plist file. The file contains a list of food items, each one containing a dictionary such as the foodName, calories, imageName, etc. However,

func loadItems() {
        if let path = Bundle.main.path(forResource: "mealData", ofType: "plist") {
            let tempDict = NSDictionary(contentsOfFile: path)
            let tempArray = (tempDict!.value(forKey: "foodItems") as! NSArray) as Array

            for dict in tempArray {
                let foodName = dict["name"]! as! String //ERROR: Ambiguous use of 'subscript' 
                let calories = dict["calories"]! as! String //ERROR: Ambiguous use of 'subscript'
                let imageName = dict["imageName"]! as! String //ERROR: Ambiguous use of 'subscript'
                let imageSize = dict["imageSize"]! as! String //ERROR: Ambiguous use of 'subscript'
                let imageType = dict["imageType"]! as! String //ERROR: Ambiguous use of 'subscript'
                let imageLink = dict["imageLink"]! as! String //ERROR: Ambiguous use of 'subscript'
   
                let f = FoodItem(name: foodName, calories: calories, imageName: imageName, imageSize: imageSize, imageType: imageType, imageLink: imageLink)
   
                foodItems.append(f)
            }
        }
    }

When I'm trying to iterate through the array created, I'm receiving this error: ✖Ambiguous use of 'subscript' in all the properties (let foodName = dict["name"]! as! String, etc, etc). I'm not sure why because I casted tempArray as an Array previously in the code, so it should be considered as an array but it is not.

Any ideas? Thank you in advance

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Answer 1

OOPer OP

May ’17

Accepted Answer

To successfully subscript to an object, `subscript` needs to be definitely declared for the Key type (in your case, it's String).

But in your code, with casting by `as Array`, the Element type is inferred as `AnyObject`, so your `dict` is of type `AnyObject`.

(It's a bit amazing because `NSArray` works as a `Collection` of `Any`.)

You can apply all methods including subscripts imported, so it can easily be ambiguous as multiple classes define their own `subscript`.

To avoid this ambiguity, your `dict` should be explicitly declared as a `Dictionary`, which means your `tempArray` needs to be an `Array` of `Dictionary`, not an `Array` of `AnyObject`.

Try something like this:

func loadItems() {
    if
        let url = Bundle.main.url(forResource: "mealData", withExtension: "plist"),
        let tempDict = NSDictionary(contentsOf: url) as? [String: Any],
        let tempArray = tempDict["foodItems"] as? [[String: Any]] //<-declare `tempArray` as Array of Dictionary
    {
        for dict in tempArray { //<-`dict` is of type `[String: Any]`
            let foodName = dict["name"]! as! String
            let calories = dict["calories"]! as! String
            let imageName = dict["imageName"]! as! String
            let imageSize = dict["imageSize"]! as! String
            let imageType = dict["imageType"]! as! String
            let imageLink = dict["imageLink"]! as! String
          
            let f = FoodItem(name: foodName, calories: calories, imageName: imageName, imageSize: imageSize, imageType: imageType, imageLink: imageLink)
          
            foodItems.append(f)
        }
    } else {
        print("mealData.plist does not exist or broken")
    }
}

0

Answer 2

blad90 OP

May ’17

Makes sense.

Thank you!

0