Swift: How to use for-in loop with an optional?

swift2 optional for-in-loop
Boon picture Boon · Sep 20, 2015 · Viewed 19.3k times · Source

What's the proper way to use for-in loop with an optional?

Right now I always perform an optional binding before looping it. Are there other idioms?

let optionalInt:[Int]? = [1, 2, 3]

if let optionalInt = optionalInt {
  for i in optionalInt {
    print(i)
  }
}

Answer

Richard Topchii picture Richard Topchii · Aug 1, 2016

If set of operations to be applied to all elements of the array, it is possible to replace for-loop with forEach{} closure and use optional chaining:

var arr: [Int]? = [1, 2, 3]
arr?.forEach{print($0)}

Related questions

Swift: guard let vs if let

I have been reading about Optionals in Swift, and I have seen examples where if let is used to check if an Optional holds a value, and in case it does – do something with the unwrapped value. However, I have …

Read More
When should I compare an optional value to nil?

Quite often, you need to write code such as the following: if someOptional != nil { // do something with the unwrapped someOptional e.g. someFunction(someOptional!) } This seems a bit verbose, and also I hear that using the ! force unwrap operator can …

Read More
Optional Int in Realm

I am trying to use an Optional Int in Realm and am getting an old error I think. Code dynamic var reps: Int? = nil Error 'Property cannot be marked dynamic because its type cannot be represented in Objective-C' I am …

Read More