NSUserDefaults.standardUserDefaults（）。stringForKey（“useremail”）返回值为空的值

Question

我正在创建登录注册页面，但有错误。当我尝试登录时，userStoredEmailuser和userStoredPassword返回null。请帮助解决这个错误。

登录代码：

let useremail=email.text; 
let userpassword=password.text; 

let userStoredEmail = NSUserDefaults.standardUserDefaults().stringForKey("useremail") //return null 

let userStoredPassword = NSUserDefaults.standardUserDefaults().stringForKey("userpassword") //return null 

// print(emails); 
// print(userStoredEmail); 

Registreration代码：

let useremail=email.text; 
let userpassword=password.text; 
let userRePassword = RePassword.text; 
//check for empty field 

//store data 

let defaults = NSUserDefaults.standardUserDefaults() 
defaults.setObject("useremail", forKey: useremail!) 
defaults.setObject("userpassword", forKey: userpassword!) 
defaults.synchronize() 

let alert1 = UIAlertController(title: "Alert", message:"Registration is succesfully complete", preferredStyle:.Alert) 
// add an action (button) 

alert1.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil)) 

presentViewController(alert1, animated: true, completion: nil) 

Answer 1

不

defaults.setObject("useremail", forKey: useremail!) 
defaults.setObject("userpassword", forKey: userpassword!) 

是，你被错误保存价值userdefaults

defaults.setObject(useremail!, forKey: "useremail") 
defaults.setObject(userpassword!, forKey: "userpassword") 

没有必要的synchronize() - 它会自动更新userdefaults

Answer 2

你存储的 “钥匙” 作为值NSUserDefaults，所以你需要编写为

defaults.setObject(useremail!, forKey:"useremail") 
defaults.setObject(userpassword!, forKey:"userpassword") 

，而不是

defaults.setObject("useremail", forKey: useremail!) 
defaults.setObject("userpassword", forKey: userpassword!)