UIAlertcontroller set attributed messages

You app is crashing because of DataType mismatch.

alert.setValue(<value>, forKey: "attributedMessage")

Here <value> must be an instance of NSMutableAttributedString.

But you are passing myAttribute Which is Dictionary.

It is trying ta call length method but it is not found on Dictionary thats why app is crashing.

Try this:

alert.setValue(myString, forKey: "attributedMessage")