flatMap is now (partly) compactMap() 관련

HACKING WITH SWIFT

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What's new in Swift?

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flatMap is now (partly) compactMap() | Changes in Swift 4.1

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flatMap is now (partly) compactMap()

Available from Swift 4.1

The flatMap() method was useful for a variety of things in Swift 4.0, but one was particularly useful: the ability to transform each object in a collection, then remove any items that were nil.

Swift Evolution proposal SE-0187 (apple/swift-evolution) suggested changing this, and as of Swift 4.1 this flatMap() variant has been renamed to compactMap() to make its meaning clearer.

For example:

let array = ["1", "2", "Fish"]
let numbers = array.compactMap { Int($0) }

That will create an Int array containing the numbers 1 and 2, because "Fish" will fail conversion to Int, return nil, and be ignored.

Other Changes in Swift 4.1

Synthesized Equatable and Hashable | Changes in Swift 4.1

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Synthesized Equatable and Hashable

Key decoding strategies for Codable | Changes in Swift 4.1

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Key decoding strategies for Codable

Conditional conformances | Changes in Swift 4.1

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Conditional conformances

Recursive constraints on associated types | Changes in Swift 4.1

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Recursive constraints on associated types

Build configuration import testing | Changes in Swift 4.1

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Build configuration import testing

Target environment testing | Changes in Swift 4.1

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Target environment testing

Download Swift 4.1 playground