What is difference between “?” and “!” in Swift?

Question

I know what \"?\" and \"!\" mean when I declare variables in Swift. But what do they mean when using these variables? For example, in this code:

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Answer 1

Both symbols ! and ? used for optionals. We should have to use !, when we make sure option type variable has value at a time and we need to take action on it.Otherwise It will crash if variable value is nil.And if you are using ?, Application will not crash in nil case.

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