CODEWITHSUNDEEP
swift
PM Extra
PM Extra

Reputation: 435

Swift 3: How to let a constant according to different case?

    let action = { () -> Action in
        if fromView == self.defaultView {
            return Action.push
        } else if toView == self.defaultView {
            return Action.pop
        } else {
            return Action.swap
        }
    }()

I want to let a constant according to different case.

Is this the right way? (It's works fine, I just want to find a more elegant way. ）

Upvotes: 0

Views: 88

Answers (3)

Venkat057
Venkat057

Reputation: 187

Please find piece of code below. If you want to use it as let constant.

let action: Action {
  get {
    switch self.defaultView {
       case fromView:
          return Action.push
       case toView:
          return Action.pop
      default:
        return Action.swap
    }
  }
}

Upvotes: 0

Luca Angeletti
Luca Angeletti

Reputation: 59526

This is the right syntax for populating a constant using your conditions

let action = { () -> Action in
    switch self.defaultView {
    case self.fromView: return .push
    case self.toView: return .pop
    default: return .swap
    }
}()

Full example

import UIKit

class ViewController: UIViewController {

    let fromView = UIView()
    let defaultView = UIView()
    let toView = UIView()

    func foo() {
        let action = { () -> Action in
            switch self.defaultView {
            case self.fromView: return .push
            case self.toView: return .pop
            default: return .swap
            }
        }()
    }
}

enum Action {
    case push, pop, swap
}

Upvotes: 0

deadbeef
deadbeef

Reputation: 5563

If you're doing this inside a method (and your action variable is not a property), you don't need the closure, you can write :

let action: Action
if fromView == self.defaultView {
    action = .push
} else if toView == self.defaultView {
    action = .pop
} else {
    action = .swap
}

If your if/else handles all the cases, the compiler will not complain that the action variable is used uninitialized.

Upvotes: 2

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