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
}
}
回答2:
Your are unwrapping something that was already unwrapped. Take a look at this stackoverflow post
来源：https://stackoverflow.com/questions/39799471/non-optional-expression-of-type-anyobject-used-in-a-check-for-optionals