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I have built a form(https://github.com/xmartlabs/Eureka) in my app and one of the input will obtain an Optional Set type. However,I need to push this set as an array to Parse for every user.But the array field in Parse only accepts NSArray as a valid data type.How do I convert it to an NSArray? I have already referred to this post (Convert native swift Set into array) but it does not seem to work in my case. Here's my code :

let user = PFUser()

print(form.rowByTag("Subjects")?.baseValue)

if let subjects = form.rowByTag("Subjects")?.baseValue
{
    let arr = Array(arrayLiteral: subjects)
    user["Subjects"] = arr as! AnyObject
}
else
{
    print("There is no subjects chosen")
}

The Subjects field is an array field in Parse. The result of the print statement and the error: enter image description here

enter image description here

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Syed Ariff
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  • `but it does not seem to work in my case` Why? How? What's the issue, what's the error message? – Eric Aya Feb 20 '16 at 12:13
  • Your issue seems to be that your objects *inside* the array are unwrapped optionals. Unwrap them before using the array. – Eric Aya Feb 20 '16 at 12:39
  • I tried unwrapping the values but I still get the same error,Or is there another way to unwrap it? Edited the question to reflect the new code btw. – Syed Ariff Feb 20 '16 at 13:01
  • Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/104034/discussion-between-syed-ariff-and-eric-d). – Syed Ariff Feb 20 '16 at 13:07

1 Answers1

3

The issue is that your objects inside the array are unwrapped optionals.

But you can't use Array(arrayLiteral: ) because it would just create an array containing the set itself, not an array of the elements in the set.

We are going to use flatMap instead, to safely unwrap the contents.

if let subjects = form.rowByTag("Subjects")?.baseValue as? Set<String> {
    let arr = subjects.flatMap { $0 }
    user["Subjects"] = arr as! AnyObject

}

Of course, if it's possible, it would be better to address the source of the issue and have the optionals safely unwrapped earlier in the code flow, that way you would be able to use Array(subjects) as usual.

Syed Ariff
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Eric Aya
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