Join Scott Gardner for an in-depth discussion in this video Define optional protocol requirements, part of Swift 3 Essential Training: Beyond the Basics.
- In order to support optional protocol requirements…in objective C, protocol is written in Swift Two…that contained optional requirements…needed to be marked with the @objc attribute.…In swift three, each optional requirement…needs to be individually marked with the @objc attribute.…I'm continuing in this same exercise file…from the previous video.…I clarified earlier that an optional property requirement…such as the subtitle property and has title,…is not the same thing as an optional requirement.…
To make subtitle an actual optional requirement,…first I'll add the optional keyword in its definition.…I get an error that informs me,…optional can only be applied to an @objc protocol.…So I'll add that attribute to the protocol definition.…And now I get another error,…indicating that optional requirements…are an objective c compatibility feature.…Along with a fix it to add the @objc attribute…to the requirement, I'll do that.…When making a protocol requirement optional,…it also relegates adoption of the protocol to classes.…
- 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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