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I'm actually trying to parse a Json object with Swift3 on Xcode8.1. This is my code:
if let objData = objJson["DATA"] as! NSDictionary? {
var msg: String = ""
if let tmp = objData.object(forKey: "Message") {
msg = tmp as! String
} else {
print("NIIILLLLL")
}
}
I'm getting this error message: Could not cast value of type 'NSNull' (0x4587b68) to 'NSString' (0x366d5f4) at this line msg = tmp as! String.
I'm not understanding why I'm getting this error because the type of tmp is Any and it should display the print instead of convert tmp as! String
Thank you for the help,
514
We can use NSNull to represent nil objects in collections, and we typically see NSNull when we convert JSON to Objective-C objects and the JSON contained null values. Our preferred way to check if something is NSNull is [[NSNull null] isEqual:something] .
In Swift, you can also use nil-coalescing operator to check whether a optional contains a value or not. It is defined as (a ?? b) . It unwraps an optional a and returns it if it contains a value, or returns a default value b if a is nil.
NULL and nil are equal to each other, but nil is an object value while NULL is a generic pointer value ((void*)0, to be specific). [NSNull null] is an object that's meant to stand in for nil in situations where nil isn't allowed. For example, you can't have a nil value in an NSArray.
Swift – Check if Variable is not nil If optional variable is assigned with nil , then this says that there is no value in this variable. To check if this variable is not nil, we can use Swift Inequality Operator !=
You can add casting in let.
if let tmp = objData.object(forKey: "Message") as? String {
msg = tmp
}
With Swift 3, for example:
fileprivate var rawNull: NSNull = NSNull()
public var object: Any {
get {
return self.rawNull
}
}
You can check field object as:
if self.object is NSNull {
// nil
}
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