Swift3 Type 'String' does not conform to protocol 'Sequence'

在Swift3中如果要用for循环遍历字符串String，用以前的方法可能会报标题中的错误，只需要这么做就好了

for character in string.characters {}

字符串倒序也很容易

func reverseString(string: String) -> String {
  return String(string.characters.reverse())
}

In Swift 3reverse()has been renamed toreversed()