CODEWITHSUNDEEP
swift
lurning too koad
lurning too koad

Reputation: 2964

Difference between string array with quotations and without?

UserDefaults.standard.set(["a", "b"], forKey: "xxx")

if let def = UserDefaults.standard.array(forKey: "xxx") as? [String] {
    print(def) // ["a", "b"]
}

if let def = UserDefaults.standard.array(forKey: "xxx") {
    print(def) // [a, b]
}

In the second example, when you don't explicitly cast the array to [String] (leaving it as [Any]), the print console produces an array without quotation marks which suggests they aren't strings. What is happening here?

Upvotes: 1

Views: 145

Answers (2)

TylerP
TylerP

Reputation: 9829

If you print out their types, you'll find that the second def is an array of NSTaggedPointerStrings. NSTaggedPointerString is a private subclass of NSString, and NSStrings print out to the console without the double quotes when inside an array.

UserDefaults.standard.set(["a", "b"], forKey: "xxx")

if let def = UserDefaults.standard.array(forKey: "xxx") as? [String] {
    print(def) // ["a", "b"]
    print(type(of: def)) // Array<String>

    for element in def {
        print(element, "is a", type(of: element)) // a is a String
                                                  // b is a String
    }
}

if let def = UserDefaults.standard.array(forKey: "xxx") {
    print(def) // [a, b]
    print(type(of: def)) // Array<Any>

    for element in def {
        print(element, "is a", type(of: element)) // a is a NSTaggedPointerString
                                                  // b is a NSTaggedPointerString
    }
}

print(["a", "b"] as [NSString]) // [a, b]

Upvotes: 1

Vikram Parimi
Vikram Parimi

Reputation: 777

In the first example, you are optional unwrapping/inferring the array to an array of strings. So it's logged as ["a", "b"] which is the standard representation of string value in double-quotes.

In the second one, the type is not inferred so by default it's logged as an array of Any type values where you don't see any double-quotes.

Upvotes: 0

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