nickarthur

import Foundation
import PlaygroundSupport

PlaygroundPage.current.needsIndefiniteExecution = true

// CHANGE THIS TO TRUE FOR the lock queue to be used
let useLocks = false

var counter : Int = 0

nickarthur

public class myClass {
  
}
// the public keyword defines the access control for this class

nickarthur

if let actualInteger = possibleInteger,
   let actualDouble = actualInteger as? Double {
       // do stuff with actualInteger
       // or actualDouble
}

nickarthur

if let acutualInteger = possibleInteger,
   var actualString = possibleString {
       // do stuff
}

nickarthur

func add(firstPossibleInteger: Int?, secondPossibleInteger: Int?) -> Int? {
    guard let firstNumber = firstPossibleInteger, 
          let secondNumber = secondPossibleNumber
          else { return nil }    // or 0 if you want to return a
                                 // non-optional value
  
    return (firstNumber + secondNumber)
}

nickarthur

if let actualDouble = possibleDouble {
    // do stuff with actualDouble
}

nickarthur

if let actualInteger = possibleInteger as? Int {
    // do stuff with actual integer
    print(actualInteger)    // prints 3
    print(possibleInteger)  // prints Optional(3)
    // actualInteger's scope ends here
}

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class CustomTableViewCell: UITableViewCell {
   @IBOutlet weak var imageView: UIImageView!
   @IBOutlet weak var title: UILabel!
   @IBOutlet weak var subtitle: UILabel!
}

class TableView: UITableView {
    func tableView(_ tableView: UITableView,
         cellForRowAt indexPath: IndexPath) -> UITableViewCell {
          let cell = tableView.dequeueReusableCell(with: identifier)

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var integerValue = 42
var stringValue = String(describing: 42)

var doubleValue = integerValue as! Double
var floatValue = Int(stringValue) as? Float

var array: [String] = ["eggs", "bacon", "ham", "cheese"]
let arrayCount = Double(array.count as? String)

var numArray: [Int] = [1, 2, 3, 4, 5]

nickarthur

var integerValue = 42
var stringValue = integerValue as? String