Subclass AFNetworking JSON Response Serialization to insert JSON response body in to error data in Swift 2 - swift

Question

AFNetworking does not return the JSON response body when it fails (e.g. 400 status code), therefore you must subclass AFJSONResponseSerializer and fill in the error object with such. This is the recommended here and an example is here
Up until Swift 2, I used the following code to achieve such:
import Foundation
let JSONResponseSerializerWithDataKey : String = "JSONResponseSerializerWithDataKey"
let JSONResponseUndefinedAPIFailureReason : String = "UNKNOWN_ERROR"
class JSONResponseSerializerWithData: AFJSONResponseSerializer
{
override func responseObjectForResponse (response: NSURLResponse, data: NSData, error: AutoreleasingUnsafeMutablePointer
<NSError?>) -> AnyObject
{
var json : AnyObject = super.responseObjectForResponse(response, data: data, error: error) as AnyObject
if (error.memory? != nil)
{
var errorValue = error.memory!
var userInfo = errorValue.userInfo
if let errorDetail = json["detail"] as? String
{
userInfo![JSONResponseSerializerWithDataKey] = errorDetail
}
else
{
userInfo![JSONResponseSerializerWithDataKey] = JSONResponseUndefinedAPIFailureReason
}
error.memory = NSError(domain: errorValue.domain, code: errorValue.code, userInfo: userInfo)
}
return json
}
}
Start with Swift 2, a new type of Error handling was introduced.
The signature of the above function is now:
override func responseObjectForResponse(response: NSURLResponse!, data: NSData!) throws -> AnyObject
I am having trouble achieving the same as above inside a do-catch statement as it seems the failure does not invoke the catch statement, and thus there is no access to the error object. Further, new ErrorTypes are essentially empty and don't contain
This is what I've tried, but the catch statement is never called:
class JSONResponseSerializerWithData: AFJSONResponseSerializer
{
override func responseObjectForResponse(response: NSURLResponse!, data: NSData!) throws -> AnyObject
{
do
{
return try super.responseObjectForResponse(response, data: data)
}
catch
{
let nsError = (error as NSError)
var userInfo = nsError.userInfo
if let errorDetail = userInfo["detail"] as? String
{
userInfo[JSONResponseSerializerWithDataKey] = errorDetail
}
else
{
userInfo[JSONResponseSerializerWithDataKey] = JSONResponseUndefinedAPIFailureReason
}
throw NSError(domain: nsError.domain, code: nsError.code, userInfo: userInfo)
}
}
}
I've tried stepping through the AFNetworking2 Library an the body of the response is there, so I could sub-class it in Objective-C rather than Swift, but would prefer doing such if possible.
Am I handling this incorrectly with a do-catch statement? Any pointers in the right direction would be greatly appreciated.

Answer 1

After more digging, I have found that the issue is as described here.
The error is not thrown, only filled, therefore catch is never called. To induce this old behaviour you can add "NS_SWIFT_NOTHROW" to the end of the Objective-C signature in the header file as described here
This will change the signature to:
override func responseObjectForResponse(response: NSURLResponse?, data: NSData?, error: NSErrorPointer) -> AnyObject?
Which can then be used like before.