Retrieving String Value from User Defaults in Swift 3

问题

I have a method that sets a String value in UserDefaults, but when I try to retrieve the value in a print statement, I get nil. Can anyone see what I am doing incorrectly?

    static func setPreferredUnitsOfMeasurementSystem(_ system: UnitsOfMeasurementSystem) {
        // system.rawValue is of type String
        UserDefaults.standard().set(system.rawValue, forKey: unitsOfMeasurementSystemKey)
        print(UserDefaults.standard().string(forKey: unitsOfMeasurementSystemKey))
    }

回答1:

I just ran into the same issue. Seems like a simulator bug. Restarting your Mac and running JUST the iOS 10 sim seems to fix it. See Save dictionary in userdefaults in swift 3 with xcode 8.

来源：https://stackoverflow.com/questions/38135930/retrieving-string-value-from-user-defaults-in-swift-3