为什么会看到错误“格式不是字符串文字且没有格式参数”？

Question

i am creating a music application in iphone where i am integrating twitter in my iphone so that a user can listen to a particular song click on the twitter tab ,log in to twitter and post his comment in to twitter.and i need that his username and password should be saved when he click on save username and password button so that he remain logged in when he is in the application.

I have done the code of saving username and password but i get an error indicating that ""FORMAT IS NOT A STRING LITERAL AND NO FORMAT ARGUMENTS""

Here is my code:

-(IBAction)SaveAll:(id)sender{


    UsernameString =[[NSString alloc]initWithFormat:text1.text]; "FORMAT IS NOT A STRING LITERAL AND NO FORMAT ARGUMENTS"

    [text1 setText:UsernameString];
    NSUserDefaults *UsernameDefault =[NSUserDefaults standardUserDefaults];
    [UsernameDefault setObject:UsernameString forKey:@"Stringkey"];



    PasswordString =[[NSString alloc]initWithFormat:text2.text]; "FORMAT IS NOT A STRING LITERAL AND NO FORMAT ARGUMENTS"

    [text2 setText:PasswordString];
    NSUserDefaults *PasswordDefault =[NSUserDefaults standardUserDefaults];
    [PasswordDefault setObject:PasswordString forKey:@"Stringkey2"];

}

Please help me in solving this problem so that when i click on the username and password button my username and password should be saved.

Answer 1

Use InitWithFormat if you want to create a String that is composed by several components, like a string and an integer for example then you would do something like this

NSString *myString = [NSString stringWithFormat:@"%@ costs %i"itemName, itemprice];

itemName would be an NSString Object, itemprice would be an integer.

in your case, try doing it the following way:

UsernameString =[[NSString alloc]initWithString:text1.text];

or even easier

UsernameString = text1.text;

note: I would NOT recommend to store Passwords or any other sensitive information into userdefaults a better (more safe/secure way) to store passwords is to use the devices keychain, where stored information is heavily encrypted and access happens in a safe way.

also it's easy to use:

Simple iPhone Tutorial: Password Management using the keychain by using SFHFKeychainUtils

Hope that helps.