April 2026
Intermediate
683 pages
25h 29m
English
Content preview from Swift
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10.7 Protocols as Function Parameters
In Swift, a function can import or return a value that conforms to a protocol, such as a class or struct instance. Functions returning a protocol can effectively act like a factory or builder. Although this sounds simple enough, there are different ways to return protocol-conforming types, which will be explored in this section.
10.7.1 Protocol Type
A function can use a protocol type directly. For instance, returning a strict protocol type via casting is the most basic approach. This approach is demonstrated in Listing 10.17, where you should focus on the makeRandomShape function.
protocol Shape { var area: Double { get }}class Circle: Shape { let radius: Double init(radius: Double) { self.radius
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