Join Scott Gardner for an in-depth discussion in this video Use type checking and casting operators, part of Swift 3 Essential Training: Beyond the Basics.
- [Instructor] I'm returning to the exercise file…that I have been using throughout…most of this chapter.…The Is and As operators I showed you in the last chapter…are also frequently used when working with protocols.…Remember when I tried to access…the average rating method of the items…in the first card I created?…Even though both items in the cart…also can form to a Ratable,…Ratable's average rating method…is not currently available.…This is because when I define cart…to be an array of Purchasable,…I was essentially casting any items added to that array…as instances of Purchasable…and only it's properties and methods will be available.…
I can use the Is operator to check…if an instance conforms into to a protocol.…For instance, I'll check if item is Ratable,…and if so, I'll use the As operator to cast item…as an instance of Ratable…so that I can access Ratable's members.…I'm getting an error.…Purchasable is not convertible to Ratable,…did you mean to as! to force downcast?…This error message could be improved.…
- Adding source files, resources, links, and literals
- Adding pages to a playground
- Using overflow operators and bitwise operators
- Using ranges with strings
- Creating complex sequences
- Chaining higher-order functions
- Defining lazy properties
- Using failable initializers
- Mutating methods
- Working with singletons
- Nesting function types
- Creating error types and recursive enumerations
- Extending concrete types
- Referencing selectors and key paths
- Working with protocol-oriented programming
- Defining class-only protocols and optional protocols
- Using option sets, type checking, and casting operators
Skill Level Intermediate
Core Data for iOS and macOS Enterprise Developerswith Jon Bott1h 46m Intermediate
Distributing Your iOS App for Testing with TestFlightwith Ron Buencamino35m 10s Intermediate
iOS App Development: Test-Driven Developmentwith Harrison Ferrone2h 14m Intermediate
3. Strings and Characters
4. Sequences and Collections
5. Control Flow
6. Value and Reference Types
9. Access Control
Understand access control3m 47s
Next steps1m 2s
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