Swift NSUserDefaults setString:forKey:?

Question

NSUserDefaults has integerForKey:, setInteger:forKey: and stringForKey:, but does not have setString:forKey:.

How do you set a string to NSUserDefaults? It has setObject:forKey: but, in Swift, String is a struct. Is it ok to use setObject:forKey: to store a string?

Leo Dabus · Answer 1 · 2022-11-06T19:06:42.790

update: Xcode 13.2.1 • Swift 5.5.2

let string = "Hello World"

UserDefaults.standard.set(string, forKey: "string")

if let loadedString = UserDefaults.standard.string(forKey: "string") {
    print(loadedString) // "Hello World"
}

The nice thing about Swift is that it allows to you to easily extend the language. You can create your own date(forKey:) extending UserDefaults to create an instance method as follow:

extension UserDefaults {
    func date(forKey defaultName:String) -> Date? {
        object(forKey: defaultName) as? Date
    }
}

let userName = "Chris Lattner"
let userAddress = "1 Infinite Loop, Cupertino, CA 95014, United States"
let userDOB = DateComponents(calendar: .init(identifier: .gregorian), year: 1978).date!

UserDefaults.standard.set(userName, forKey: "userName")
UserDefaults.standard.set(userAddress, forKey: "userAddress")
UserDefaults.standard.set(userDOB, forKey: "userDOB")

let loadedUserName = UserDefaults.standard.string(forKey: "userName")
let loadedUserAddress = UserDefaults.standard.string(forKey: "userAddress")
let loadedUserDOB = UserDefaults.standard.date(forKey: "userDOB")

print(loadedUserName ?? "nil")    // "Chris Lattner"
print(loadedUserAddress ?? "nil") // "1 Infinite Loop, Cupertino, CA 95014, United States"
print(loadedUserDOB?.description(with: .init(identifier: "en_US")) ?? "nil")  // "Sunday, January 1, 1978 at 12:00:00

Daniel Storm · Answer 2 · 2017-05-07T14:54:37.937

19

Swift 3 removed .setObject. Use .set instead. For example:

// Create UserDefaults
let defaults = UserDefaults.standard

// Save String value to UserDefaults
// Using defaults.set(value: Any?, forKey: String)
defaults.set("Some string you want to save", forKey: "savedString")

// Get the String from UserDefaults
if let myString = defaults.string(forKey: "savedString") {
    print("defaults savedString: \(myString)")
}

edited May 07 '17 at 14:54

answered Oct 16 '16 at 15:04

Daniel Storm

18,301
9
84
152

2

Short and objective. Thanks! – Paula Hasstenteufel Apr 05 '17 at 09:37
1

What about retrieving the value with defaults.string(forKey: "savedString")? That seems to work. – RanLearns May 07 '17 at 10:38
@RanLearns great point. Not sure why I did it like that initially. Edited. – Daniel Storm May 07 '17 at 14:55

score 14 · Accepted Answer · edited May 25 '21 at 06:31

14

The reason that setObject can be used to apply a string is found in the discussion of the reference:

discussion

Since Swift String is bridged to NSString, the usage of setObject is valid. However as the other types mentioned are not accepted in NSUserDefaults using the setObject setter; they have their own convenience setters.

convenience-inits

Notwithstanding this, almost anything one can think of can be serialized and placed into NSUserDefaults using setObject with an NSData argument (as noted elsewhere on SO).

edited May 25 '21 at 06:31

Dimitar Nestorov

2,411
24
29

answered Mar 18 '15 at 16:24

Tommie C.

12,895
5
82
100

Thank you for your answer. The other answers are exact and appreciated but I took this answer to accept because it mentions about Swift String structure bridged to NSString class. Also the usage of NSData is helpful. – Yoichi Tagaya Mar 19 '15 at 03:16

score 4 · Answer 4 · answered Mar 18 '15 at 15:59

4

You can definitly use setObject:forKey:, the NSDictionary method or even setValue:forkey: which is a KVC method.

It'll work just fine.

answered Mar 18 '15 at 15:59

Gil Sand

5,802
5
36
78

Swift NSUserDefaults setString:forKey:?

4 Answers4

Linked