用户默认快速 4答案

【问题标题】：UserDefaults swift 4用户默认快速 4
【发布时间】：2018-05-04 06:08:24
【问题描述】：

我对 UserDefaults 有疑问。

import Foundation

class Utility: NSObject {
    func storeBaseDetail(firstname:String,lastname:String,picStr:String,email:String,usrname:String,user_Id:String) {
        UserDefaults.standard.set(firstname, forKey: "firstname")
        UserDefaults.standard.set(lastname, forKey: "lastname")
        UserDefaults.standard.set(picStr, forKey: "picStr")
        UserDefaults.standard.set(email, forKey: "email")
        UserDefaults.standard.set(usrname, forKey: "usrname")
        UserDefaults.standard.set(user_Id, forKey: "id")
        UserDefaults.standard.synchronize()
    }

    func getBaseDetail()->(firstName:String,lastName:String,picStr:String,email:String,usrname:String,user_Id:String){
        return ((UserDefaults.standard.value(forKey: "firstname") as! String),(UserDefaults.standard.value(forKey: "lastname") as! String),(UserDefaults.standard.value(forKey: "picStr") as? String)!,(UserDefaults.standard.value(forKey: "email") as! String),(UserDefaults.standard.value(forKey: "usrname") as! String),(UserDefaults.standard.value(forKey: "id") as! String))
    }

    func storeBaseDetail(firstname:String,lastname:String,picStr:String,email:String,usrname:String,user_Id:String) {
        UserDefaults.standard.set(firstname, forKey: "firstname")
        UserDefaults.standard.set(lastname, forKey: "lastname")
        UserDefaults.standard.set(picStr, forKey: "picStr")
        UserDefaults.standard.set(email, forKey: "email")
        UserDefaults.standard.set(usrname, forKey: "usrname")
        UserDefaults.standard.set(user_Id, forKey: "id")
        UserDefaults.standard.synchronize()
    }

    func getBaseDetail()->(firstName:String,lastName:String,picStr:String,email:String,usrname:String,user_Id:String){
        return ((UserDefaults.standard.value(forKey: "firstname") as! String),(UserDefaults.standard.value(forKey: "lastname") as! String),(UserDefaults.standard.value(forKey: "picStr") as? String)!,(UserDefaults.standard.value(forKey: "email") as! String),(UserDefaults.standard.value(forKey: "usrname") as! String),(UserDefaults.standard.value(forKey: "id") as! String))
    }
}

如果我称它为 UserDefaults：

if  Utility().getBaseDetail().firstName != ""{
    userNameLbl.text = "\(Utility().getBaseDetail().firstName) \(Utility().getBaseDetail().lastName)"
}

我收到此错误：

线程 1：致命错误：在展开可选值时意外发现 nil

【问题讨论】：

标签： swift dataset nsuserdefaults

【解决方案1】：

用这个改变你的功能

func getBaseDetail()->(firstName:String,lastName:String,picStr:String,email:String,usrname:String,user_Id:String){
    return ((UserDefaults.standard.value(forKey: "firstname") as? String ?? ""),(UserDefaults.standard.value(forKey: "lastname") as? String ?? ""),(UserDefaults.standard.value(forKey: "picStr") as? String ?? ""),(UserDefaults.standard.value(forKey: "email") as? String ?? ""),(UserDefaults.standard.value(forKey: "usrname") as? String ?? ""),(UserDefaults.standard.value(forKey: "id") as? String ?? ""))
}

【讨论】：

【解决方案2】：

这是避免 nil 值的正确方法，

func getBaseDetail()->(firstName:String?,lastName:String?,picStr:String?,email:String?,usrname:String?,user_Id:String?){
    return ((UserDefaults.standard.value(forKey: "firstname") as? String),(UserDefaults.standard.value(forKey: "lastname") as? String),(UserDefaults.standard.value(forKey: "picStr") as? String),(UserDefaults.standard.value(forKey: "email") as? String),(UserDefaults.standard.value(forKey: "usrname") as? String),(UserDefaults.standard.value(forKey: "id") as? String))
  }

在其他类中创建 Utility 的实例，

  let utilityInstance = Utility()

然后使用 if let 获取您的值，

if let emailValue = utilityInstance.getBaseDetail().email{
      print(emailValue)
    }

所以，如果值存在则打印，如果没有值则跳过。

【讨论】：