Ie, the array of optionals is compact mapped, but only if all the elements are not nil, otherwise the resulting optional array will be nil. ![]() So what happens when any of the elements is nil? let x: Int? = 1 Let a: ? = // □ Cannot convert value of type 'Int?' to expected element type 'Array.ArrayLiteralElement' (aka 'Int')Īlso, the following program is equivalent to the first AFAICT, yet there's no warning: let x: Int? = 1 It also says that this does nothing and provides the fixit "Remove as ? ", but applying the fixit will result in a compiler error (so clearly it did something rather than nothing): let x: Int? = 1 The warning says I'm downcasting from Int? to Int although what happens is that a is casted into a ?. var i users0'Age' as Int but if you are unsure and want a nil value if it is not an Int then use. Type checking is the process of figuring out whether an instance belongs to a particular type. ![]() These are some more subjects and approaches to the Swift idea of typecasting: Type Checking. If the downcast is unsuccessful, we invoke Animal’s makeSound function. Different types of questions require different responses. If you are sure the result is an Int then use. If the downcast is successful, we invoke Dog’s makeSound function. ![]() I'm trying to dynamically change the information within a view based on certain questions. Let a: ? = as? // ⚠️ Conditional downcast from 'Int?' to 'Int' does nothing I'm new to swift & swift UI so forgive me if there is an obvious answer to this question. Note the warning in this program: let x: Int? = 1
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