Boolean toggling 관련

HACKING WITH SWIFT

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What's new in Swift?

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Boolean toggling | Changes in Swift 4.2

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Boolean toggling

Available from Swift 4.2

SE-0199 (apple/swift-evolution) introduced a new toggle() method to booleans that flip them between true and false..

The entire code to implement proposal is only a handful of lines of Swift:

extension Bool {
   mutating func toggle() {
      self = !self
   }
}

However, the end result makes for much more natural Swift code:

var loggedIn = false
loggedIn.toggle()

As noted in the proposal, this is particularly useful in more complex data structures: myVar.prop1.prop2.enabled.toggle() avoids the potential typing errors that could be caused using manual negation.

The proposal makes Swift easier and safer to write, and is purely additive, so I think most folks will switch to using it quickly enough.

Other Changes in Swift 4.2

Derived collections of enum cases | Changes in Swift 4.2

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Derived collections of enum cases

Warning and error diagnostic directives | Changes in Swift 4.2

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Warning and error diagnostic directives

Dynamic member look up | Changes in Swift 4.2

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Dynamic member look up

Enhanced conditional conformances | Changes in Swift 4.2

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Enhanced conditional conformances

Random number generation and shuffling | Changes in Swift 4.2

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Random number generation and shuffling

Simpler, more secure hashing | Changes in Swift 4.2

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Simpler, more secure hashing

Checking sequence elements match a condition | Changes in Swift 4.2

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Checking sequence elements match a condition

In-place collection element removal | Changes in Swift 4.2

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In-place collection element removal

Download Swift 4.2 playground