问题:

I created an extension on 'Dictionary' to help me parse JSON. The method below helps me do this:

func toJSONString() -> String? {
    if let dict = self as? AnyObject {
        if let data = try? JSONSerialization.data(withJSONObject: dict, options: JSONSerialization.WritingOptions(rawValue: 0)) {
            if let json = String(data: data, encoding: String.Encoding.utf8) {
                return json
            }
        }
    }
    return nil
}

The issue occurs on this line:

if let dict = self as? AnyObject {

I get a warning saying "Non-optional expression of type 'AnyObject' used in a check for optionals"

How do I go about solving this issue?

回答1:

Simply remove the line that causes warning from your code and pass self as is for the JSONSerialization function. This should work without any issues:

extension Dictionary {

    func toJSONString() -> String? {
        if let data = try? JSONSerialization.data(withJSONObject: self, options: JSONSerialization.WritingOptions(rawValue: 0)) {
            if let json = String(data: data, encoding: String.Encoding.utf8) {
                return json
            }
        }

        return nil
    }
}