Usage of where in if let assignment in Swift

ios swift where optional swift3
Fabrizio Bartolomucci picture Fabrizio Bartolomucci · Aug 4, 2016 · Viewed 29k times · Source

The Swift documentation at page 61 of the Swift manual hints to the possibility of using where to join an optional binding with a regular condition. Yet when I do it I have a warning suggesting me to substitute the where with a comma like in the following piece of code:

if let geocodingError = error as? NSError where geocodingError.code == 2

Answer

Grimxn picture Grimxn · Aug 4, 2016

In Swift 3 this syntax has changed.

What was

if let x = y, a = b where a == x {

Is now

if let x = y, let a = b, a == x {

The justification is that each sub-clause of the if ... { is now an independent boolean test.

See the Xcode Release notes & the Swift Evolution proposal for more info about this change.

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