Cannot assign a value of type 'String' to a value of type 'String' in Xcode7

Question

I just upgraded to Swift 2.0 And Xcode 7 Beta and I am getting the error:

Cannot assign a value of type 'String' to a value of type 'String'

while writing:

 var string = (change[NSKeyValueChangeNewKey]) as! String?

I would file a radar. The bang in the as! seems necessary because you're forcing a downcast. But you also want to include the ? to indicate it's a String type that may not have a value. This is different from (1) a String that will always have a value, and from (2) a generic type (AnyObject). I see String? as a very distinct, third option. — Craig Otis
– Craig Otis, Commented Jun 11, 2015 at 0:47
Swift's error codes are really, really bad sometimes. Treat the error message as the compiler saying "Duh... I don't understand!" and proceed from there. Patricks suggestion of optional binding is worth trying. — Duncan C
– Duncan C, Commented Jun 11, 2015 at 1:16

Patrick Lynch · Accepted Answer · 2015-06-11 00:30:47Z

1

I think the as! String? part is the problem.

You should probably be doing this:

if let string = change[NSKeyValueChangeNewKey] as? String {
    // Do something with `string`
}

answered Jun 11, 2015 at 0:30

Patrick Lynch

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