Important facts of closures in Swift

• You can write a closure without a name by surrounding code with braces ({}). Use in in a closure to seperate the arguments and return type from its body.

    Int numbers = [1,2,3,4,5,6]
    numbers.map({ (number:Int) -> Int in
      let result = number * 4
      return result}
    )

• You can omit the type of its params, its return type or both when a closure’s type is already known.


• Single statement closures implicitly return the value of their only statment.
  
  

  Int numbers = [1,2,3,4,5,6]
  numbers.map({number in number*3})

  
  


• You can refer to params by numbers instead of names. The $0 is the first input parameter for the closure. If the closure had multiple parameters, the second parameter would be $1, the third $2, etcetera.

 numbers.map({$0*3})

• When a closure is the only argument to a function, you can omit the parentheses entirely.

numbers.map{$0*3}numbers.sorted{$0 > $1}

• A closure passed as the last argument to a function can appear immediately after the paranthesis.

numbers.reduce(0){$0+$1}