iOS อยากทราบแนวทางทำแอพ login แล้วจำให้เรา login ตลอดเวลา จนกว่าเราจะกด logout อะครับ รบกวนผู้รุ้ด้วยนะครับ

- (IBAction)save:(id)sender
{
    // Hide the keyboard
    [firstNameTextField resignFirstResponder];
    [lastNameTextField resignFirstResponder];
    [ageTextField resignFirstResponder];
    // Create strings and integer to store the text info
    NSString *firstName = [firstNameTextField text];
    NSString *lastName  = [lastNameTextField text];
    int age = [[ageTextField text] integerValue];
    // Create instances of NSData
    UIImage *contactImage = contactImageView.image;
    NSData *imageData = UIImageJPEGRepresentation(contactImage, 100);
    // Store the data
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:firstName forKey:@"firstName"];
    [defaults setObject:lastName forKey:@"lastname"];
    [defaults setInteger:age forKey:@"age"];
    [defaults setObject:imageData forKey:@"image"];
    [defaults synchronize];
    NSLog(@"Data saved");
}