Introducing Protocol-Oriented Programming in Swift 2

最新推荐文章于 2020-07-23 02:01:00 发布

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最新推荐文章于 2020-07-23 02:01:00 发布

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分类专栏： Swift 2 Tutorials

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*Becuase types can conform to more than one protocol, they can be decorated with default behaviors from multiple protocols. Unlike multiple inheritance of classes which some programming languages support, protocol extensions do not introduce any additional state.

Protocols can be adopted by classes, structs and enums. Base classes and inheritance are restricted to class types.

*CollectionType is a protocol conformed to by types such as arrays and dictionaries in Swift.

*Conforming to BooleanType means your type needs to have a boolValue property so it acts like a Boolean.

extension BooleanType where Self: Bird {
  var boolValue: Bool {
    return self.canFly
  }
}

if UnladenSwallow.African {
  print("I can fly!")
} else {
  print("Guess I’ll just sit here :[")
}

This extension will make the canFly property represent each Bird type's Boolean value.

// Counts the number of characters in the array
["frog", "pants"].map { $0.length }.reduce(0) { $0 + $1 } // returns 9

Swift helps promote functional programming paradigms by including methods such as map, reduce, and filter in the standard library. These methods exist on various CollectionType members such as Array.