AppleCEO

descriptionAttributedString.addAttribute(NSAttributedString.Key.backgroundColor, value: UIColor.blue, range: NSRange(location: 0, length: 2))

AppleCEO

attributedString.addAttribute(NSAttributedString.Key.backgroundColor, value: UIColor.black.withAlphaComponent(0.5), range: NSRange(location: 5, length: 4))

AppleCEO

@IBAction func nextButtonTouched(_ sender: Any) {
      self.firstLabel.textColor = UIColor.blue
      self.firstLabel.backgroundColor = UIColor.yellow
      self.firstLabel.alpha = 0.5
  }

AppleCEO

let array = [1, 2, 3, 4, 5]

let arrayReturned = array.map({ (number: Int) -> Int in
    let result = 2 * number
    return result
}).map({ (number: Int) -> Int in
    let result = number / 2
    return result
})

AppleCEO

let set:Set = [1, 2, 3, 4, 5]

let setReturned = set.map({ (number: Int) -> Int in
    let result = 2 * number
    return result
})

AppleCEO

let optional:Optional = 1

let optionalReturned = optional.map({ (number: Int) -> Int in
    let result = 2 * number
    return result
}).map({ (number: Int) -> Int in
    let result = number / 2
    return result
})

AppleCEO

let dictionary:Dictionary = [1:"int",3:"hi"]

let dictionaryReturned = dictionary.map({ (key: Int, value: String) -> Int in
    let result = 2 * key
    return result
})

AppleCEO

protocol Multipleiable {
    static func * (lhs: Self, rhs: Self) -> Self
}

extension Int: Multipleiable {}
extension Double: Multipleiable {}

infix operator ** : MultiplicationPrecedence

func **<T> (lhs: T, rhs: T) -> T where T: Multipleiable {

AppleCEO

infix operator ** : MultiplicationPrecedence

func ** (lhs: Int, rhs: Int) -> Int {
    return lhs * rhs
}

3 ** 4
// result : 12

AppleCEO

func **<T> (lhs: T, rhs: T) -> T where T: Multipleiable {
    return lhs * rhs
}