Question 68470 in IOS Swift Question posted in
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Is it complusory to use "in" keyword in closure? If no then what is the syntax wise difference between closure and computed property in swift? – Ios swift

In swift use of get and set is not compulsory and if use of "in" in closure is also not compulsory then how to differentiate a closure and computed property?

Like in below example greet is a closure or computed property?

var greet = {
  return 4+3
}

greet()
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2

Answers


  1. 0

    greet is a closure. A computed property is

    var greet : Int {
  return 4+3
}

greet // without parentheses

    And "in" in closure is also not compulsory if a parameter is passed (by the way the return keyword is not compulsory)

    var greet = { x in
  4+x
}

greet(4)

    unless you use the shorthand syntax

    var greet = {
   4+$0
}

greet(4)
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  2. 0

    You use the keyword in when you need to pass a parameter.

    There are also differences between functions and computed properties: if you use the symbol =, you are equalling your variable to a function, so you need to call greet().

    If instead = you use :, you have a computed property, call greet.

    Here’s a list of different cases:

            // greet is a function, you need to call greet()
        var greet = {
          return 4 + 3
        }
        print(greet()) // 7

        // greet2 is a computed property, you need to call greet2
        var greet2: Int {
            return 4 + 3
        }
        print(greet2) // 7

        // greet3 is a function that receives one parameter, you need to call greet3(someInt)
        var greet3 = { (parameter: Int) -> Int in
          return 4 + parameter
        }
        print(greet3(4)) // 8

        // greet4 is like greet3, but the type is declared outside
        var greet4: (Int)->Int = { parameter in
            return 4 + parameter
        }
        print(greet4(5)) // 9

        // greet5 is like greet4, where you define the function later
        var greet5: (Int) -> Int
        greet5 = { parameter in
            return 4 + parameter
        }
        print(greet5(6)) // 10
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