ios - swift NSUserDefaults setString :forKey:?

Question

NSUserDefaults 有 integerForKey:、setInteger:forKey: 和 stringForKey:，但没有 setString:forKey:.

如何将字符串设置为 NSUserDefaults？它有 setObject:forKey: 但是，在 Swift 中，String 是一个结构。可以用setObject:forKey:来存储字符串吗？

Answer 1

更新: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"
}

Swift 的好处在于它允许您轻松地扩展语言。您可以创建自己的 date(forKey:) 扩展 UserDefaults 以创建实例方法，如下所示:

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