[NSNull length]: unrecognized selector sent to instance 0x10f8c6fc0' swift 4 iOS - ios

Question

I am fetching data from the model in this way
if let birthdate = personInfo?.str_Birthdate {
cell.dobTF.text = birthdate
}
But app crash and return this error
'-[NSNull length]: unrecognized selector sent to instance 0x10f8c6fc0'

Answer 1

What you are getting here is NSNull. It is an object representing null in context of objective-C arrays and dictionaries. Specifically in JSONs it distinguishes between receiving field (null) instead of not receiving a field at all. In your case I assume this value is force-unwrapped as a string so the error is a bit late. Please try the following:
if let dateObject = personInfo?.str_Birthdate {
if let nullObject = dateObject as? NSNull {
// A field was returned but is (null)
} else if let stringObject = dateObject as? String {
cell.dobTF.text = stringObject
} else {
// Unknown object
}
} else {
// This field is missing
}
You can actually just convert all NSNull instances to nil using something like:
func removeNSNullInstancesFrom(_ item: Any?) -> Any? {
guard let item = item else { return nil }
if let _ = item as? NSNull {
return nil
} else if let array = item as? [Any] {
return array.compactMap { removeNSNullInstancesFrom($0) }
} else if let dictionary = item as? [String: Any] {
var newDict: [String: Any] = [String: Any]()
dictionary.forEach { item in
guard let value = removeNSNullInstancesFrom(item.value) else { return }
newDict[item.key] = value
}
return newDict
} else {
return item
}
}
You can use this on the whole response object or a specific item. In your case you can do: cell.dobTF.text = removeNSNullInstancesFrom(birthdate).
But this method should in general recursively remove all NSNull instances from fields, arrays and dictionaries which are standard for JSON.