Could not cast value of type 'NSNull' to 'NSString' in parsing Json in swift

Question

I have the following class

class BannerResponse : NSObject{

    let  URL                = \"Url\";
    let  CONTACT_NO         = \"ContactNo\";
    let  IMAGE          


        

Answer 1

One of your data[SOME_KEY] is of type NSNull instead of String and because you're forcing the cast to String by using ! the app crashes.

You can do one of two things:

1. Change your variables on the BannerResponse class to be optional. And use ? instead of ! when setting the values in your init method. Like this:

`

var title: String?

init(data: NSDictionary) 
{
    self.title = data[TITLE] as? String
}

or

2. Use ? instead of ! when setting the values in your init method but set a default value whenever dict[SOME_KEY] is nil or is not the expected type. This would look something like this:

`

if let title = data[TITLE] as? String 
{
    self.title = title
}
else
{
    self.title = "default title"
}

// Shorthand would be: 
// self.title = data[TITLE] as? String ?? "default title"

And I guess a third thing is ensure that the server never sends down null values. But this is impractical because there's no such thing as never. You should write your client-side code to assume every value in the JSON can be null or an unexpected type.