Swift BasicsLesson 10Free preview

Swift Type Casting

This lesson is part of Swift · All levels

Summary

This lesson reviews Type Casting in Swift to check the object type or treat the object as another subtype. Swift provides an 'ice' operator for type checking as well as an 'as?' operator (safe downcasting) and an 'as!' operator (forced downcasting). Understanding casting is crucial in the hierarchy of inheritance and protocol.

Key points

The 'is' operator returns the boolean value to check whether the object is a particular type of instance
Operator 'as?' tries to do the downcast and return Optional (zero value if failed)
The 'ass!' operator forces downcast and will trigger a crash if the type does not fit
Any can represent any instance type, and AnyObject represents any instance class.

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