Safety

Swift is designed for safety. It eliminates many issues of compile time. Here is a list of things that Swift handles for you:

• Type safety: Swift is very strongly typed language. If a function has the Int parameter, you must pass Int as an argument when you call it. This rule also applies to operators. Swift doesn't allow use of the wrong type:

  func increase(x: Int) -> Int {
    return x + 1
  }
  
  let x = 10
  let percent = 0.3
  let name = "Sara"
  
  x + name //Error, can't apply + operator for Int and String
  x * percent //Error, can't apply * to Int and Double
  Double(x) * percent // 3
  
  increase(x) // 11
  increase(percent) // Wrong type
  increase(name) // Wrong type

• Variables must always be initialized before use: Accessing non-initialized memory is a dangerous operation. Swift handles this problem in a very nice and safe way. It doesn't compile when you try to do that:

  var y: Int
  //y + 10 //Error, variable 'y' used before being initialized
  y = 1
  y + 10

  Constant values can't be changed after they...