从plist文件中保存和加载数字

let number: Int = 42
let dict: NSDictionary = ["number": NSNumber(value: number)]

if let plistData = try? PropertyListSerialization.data(fromPropertyList: dict, format: .xml, options: 0) {
    if let fileURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first?.appendingPathComponent("Numbers.plist") {
        do {
            try plistData.write(to: fileURL)
            print("Number saved to plist file.")
        } catch {
            print("Error saving plist file: \(error)")
        }
    }
}

if let fileURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first?.appendingPathComponent("Numbers.plist") {
    if let plistData = try? Data(contentsOf: fileURL),
       let dict = try? PropertyListSerialization.propertyList(from: plistData, options: [], format: nil) as? NSDictionary,
       let number = dict["number"] as? NSNumber {
        let loadedNumber = number.intValue
        print("Loaded number from plist file: \(loadedNumber)")
    }
}