enum FileStatus {

    case hidden
    case opened
    case password
}

struct File {

    private var content: String
    private var access: FileStatus
    private  var password: String?

    init(content: String, access: FileStatus, password: String?) {
        self.content = content
        self.access = access
        self.password = self.access == .opened ? nil : password
    }

    func showContent(password: String?) -> String {
        let resultOfProcessing: String
        switch self.access {
        case .opened:
            resultOfProcessing = self.content
        case .hidden:
            resultOfProcessing = "No access. File is hidden"
        case .password:
            if password == self.password {
                resultOfProcessing = self.content
            } else {
                resultOfProcessing = "Wrong password"
            }
        }
        return resultOfProcessing
    }

    mutating func changePasswordByMethod(newPassword: String?) {
        if newPassword != self.password && self.access != .opened {
            self.password = newPassword
            print("Success! We changed password!")
        } else {
            print("Failed. Your new password must be different from the old")
        }
    }

    var changePasswordByComputedProperty: String? {
        get {
            return self.password
        }
        set {
            if newValue != self.password && self.access != .opened {
                self.password = newValue
                print("Success! We changed password!")
            }
        }
    }

}

var movie = File(content: "Columbia pictures presents....", access: .password, password: "543")

movie.changePasswordByMethod(newPassword: "332")

print(movie.showContent(password: "111"))

movie.changePasswordByComputedProperty = "111"

print(movie.showContent(password: "111"))