swift subString处理

swift5.0上报警告：substring(to:)' is deprecated: Please use String slicing subscript with a 'partial range upto' opera
解决办法：

let subStr = String(value[..<index])   // = str.substring(to: index) is deprecated
let subStr = String(value[index...])    // = str.substring(from: index) is deprecated
let subStr = String(value[range])      // = str.substring(with: range) is deprecated