I am trying to extract the value from a JSON serialization but getting nil as the result.
App was working under Swift2 so its the conversion to Swift 3 where the issue started.
let jsonResult = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
print(jsonResult!)
let mySuccess = jsonResult?["success"] as? Int
print (mySuccess!)
The print(jsonResult!) gives the following output
{
"full_login" = 0;
"logged_in" = 1;
message = "<null>";
success = 1;
}
So all good so far and my parsing is working and I now have the data from the server.
However print(mySuccess!) gives this output
fatal error: unexpectedly found nil while unwrapping an Optional value
So I understand the output saying that the code found nil while unwrapping, so my issue now is how do I extract the value of the "Success" key as it was behaving under Swift 2 but now not so under Swift 3?
UPDATE
Sneak found a possible issue that success = 1 do not have the "" so will update question answer once I investigate.
hi you can use the concept of OPTIONAL BINDING to check for nil values.
let jsonResult = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
print(jsonResult!)
if let mySuccess = jsonResult?["success"] as? Bool
{
print (mySuccess)
}
else
{
print ("Found nil")
}
Your print log of success = 1;
demonstrates that jsonResult?["success"]
is not nil
. JSONSerialization.jsonObject can only return three things that would display as 1
: a String, a Number or value true
. As you tried to unwrap it as an Int
and it failed, the only left possibilities are that it was a String
or a Bool
.
You probably have a success
as either:
"success": true
Or:
"success": "1"
As such, you may want to do:
let mySuccess = jsonResult?["success"] as? Bool
Or:
let mySuccess = jsonResult?["success"] as? String
Or ask a change in the backend API response.
Ok so the comments were really helpful and helped me hone into the problem. I started to look at the missing "" but noticed that when I entered the following code:
for (key, value) in jsonResult!
{
print (key)
print (value)
}
I get the following output
logged_in
1
full_login
0
success
1
message
<null>
So there had to be a way to get just the value for success .
This page gave me the solution in the end. I had to use the following code:
let myResult = (jsonResult?["success"])
print("SUCCESS VALUE >> ", myResult!)
This now gives me the value of 1 and all solved. Thanks again for the comments as they helped.
I then had the issue of not realising the success value was a Bool so I had to use the following code to check for true or false:
if (jsonResult?["success"] as? Bool)!
{
okToLogIn = true
print(okToLogIn)
}
else
{
okToLogIn = false
print(okToLogIn)
}
Now all good and app working again under Swift 3.
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