Write a program to distinguish lowercase and uppercase character from String in swift

Ans : 

Method 1 : 

let string = "iOSiQA is Very Helpful WebSite to Prepare for iOS Interview."
var output = ""

for chr in string {
    var str = String(chr)
    if str.lowercaseString != str {
        output += str
    }
}
print(output)


>>> OSQAVHWPOSI

Method 2 : 

let testString = "iOSiQA is Very Helpful WebSite to Prepare for iOS Interview."
let lowerCase = NSCharacterSet.lowercaseLetterCharacterSet()
let upperCase = NSCharacterSet.uppercaseLetterCharacterSet()

for currentCharacter in testString.utf16 {
  if lowerCase.characterIsMember(currentCharacter) {
    println("Character code \(currentCharacter) is lowercase.")
  } else if upperCase.characterIsMember(currentCharacter) {
    println("Character code \(currentCharacter) is UPPERCASE.")
  } else {
    println("Character code \(currentCharacter) is neither upper- nor lowercase.")
  }

}

Method 3 : 

let testString = "Åke röstet un café in Владивосток!"
let lowerCase = CharacterSet.lowercaseLetters
let upperCase = CharacterSet.uppercaseLetters

for currentCharacter in testString.unicodeScalars {
    if lowerCase.contains(currentCharacter) {
        print("Character code \(currentCharacter) is lowercase.")
    } else if upperCase.contains(currentCharacter) {
        print("Character code \(currentCharacter) is UPPERCASE.")
    } else {
        print("Character code \(currentCharacter) is neither upper- nor lowercase.")
    }
}

Method 4 :   to identify character is uppercase or lowercase

extension Character {

        func isUpperCase() -> Bool {
            return CharacterSet.uppercaseLetters.contains(self.unicodeScalars.first!)
        }

        func isLowerCase() -> Bool {
            return CharacterSet.lowercaseLetters.contains(self.unicodeScalars.first!)
        }


  }

Write a program to reverse string in swift

Ans : 

Using Self made function : 

func reverse(_ s: String) -> String {
       var str = ""
       //.String is just like array of characters

       for character in s.characters {
            str = "\(character)" + str
            print ( str)
       }
   return str
}

print (reverse("!pleH"))


Using Swift Direct method : 

Swift 4.0

let str = "abc"

String(str.reversed())

or 

String(str.characters.reversed())