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：

//   从初始位置到index位置

letsubStr=String(value[..<index])       // = str.substring(to: index) is deprecated 

//   从index位置到字符串最后

letsubStr=String(value[index...])         // = str.substring(from: index) is deprecated

//  字符串截取中间一段

letsubStr=String(value[range])            // = str.substring(with: range) is deprecated