How can I use String substring in Swift 4 substring to is deprecated Please use String slicing subscript with a partial range from operator

Question

I have the following simple code written in Swift 3   let str    Hello  playground  let index   str index of        let newStr   str substring to  index    From Xcode 9 beta 5  I get the following warning       substring to    is deprecated  Please use String slicing subscript with a  partial range from  operator    How can this slicing subscript with partial range from be used in Swift 4

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var str    Hello  playground  let indexcut   str firstIndex of       print String str    lt indexcut     print String str indexcut          You can try in this way and will get proper results

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Hope this will help little more  -  var string    123456789    If you want a substring after some particular index   var indexStart     string index after  string startIndex     you can use any index in place of startIndex var strIndexStart     String  string indexStart       23456789   If you want a substring after removing some string at the end   var indexEnd     string index before  string endIndex  var strIndexEnd     String  string    lt indexEnd    12345678   you can also create indexes with the following code  -  var  indexWithOffset    string index string startIndex  offsetBy  4

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I have written a string extension for replacement of  String  subString   extension String            func sliceByCharacter from  Character  to  Character  - gt  String            let fromIndex   self index self index of  from    offsetBy  1          let toIndex   self index self index of  to    offsetBy  -1          return String self fromIndex   toIndex                  func sliceByString from String  to String  - gt  String              From - startIndex         var range   self range of  from          let subString   String self range  upperBound                         To - endIndex         range   subString range of  to          return String subString    lt range  lowerBound                  Usage    quot Date 1511508780012 0530  quot  sliceByString from   quot   quot   to   quot   quot   Example Result    quot 1511508780012 quot   PS  Optionals are forced to unwrap  Please add Type safety check wherever necessary

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Creating SubString  prefix and suffix  from String using Swift 4   let str   String    ilike  for i in 0   str count       let index   str index str startIndex  offsetBy  i     String Index     let prefix   str    lt index     String SubSequence     let suffix   str index        String SubSequence     print  prefix   prefix   suffix     suffix        Output  prefix   suffix   ilike prefix i  suffix   like prefix il  suffix   ike prefix ili  suffix   ke prefix ilik  suffix   e prefix ilike  suffix      If you want to generate a substring between 2 indices   use    let substring1   string startIndex   endIndex     including endIndex let subString2   string startIndex   lt endIndex     excluding endIndex

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You can create your custom subString method using extension to class String as below   extension String       func subString startIndex  Int  endIndex  Int  - gt  String           let end    endIndex - self count    1         let indexStartOfText   self index self startIndex  offsetBy  startIndex          let indexEndOfText   self index self endIndex  offsetBy  end          let substring   self indexStartOfText   lt indexEndOfText          return String substring

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Some useful extensions   extension String       func substring from  Int  to  Int  - gt  String           let start   index startIndex  offsetBy  from          let end   index start  offsetBy  to - from          return String self start    lt  end              func substring range  NSRange  - gt  String           return substring from  range lowerBound  to  range upperBound

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When programming I often have strings with just plain A-Za-z and 0-9  No need for difficult Index actions  This extension is based on the plain old left   mid   right functions   extension String           LEFT        Returns the specified number of chars from the left of the string        let str    Hello         print str left 3              Hel     func left   to  Int  - gt  String           return    self    lt self index startIndex  offsetBy  to                   RIGHT        Returns the specified number of chars from the right of the string        let str    Hello         print str left 3              llo     func right   from  Int  - gt  String           return    self self index startIndex  offsetBy  self length-from                      MID        Returns the specified number of chars from the startpoint of the string        let str    Hello         print str left 2 amount  2              ll     func mid   from  Int  amount  Int  - gt  String           let x      self self index startIndex  offsetBy  from                return x left amount

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Swift5  Java s substring method   extension String       func subString from  Int  to  Int  - gt  String          let startIndex   self index self startIndex  offsetBy  from         let endIndex   self index self startIndex  offsetBy  to         return String self startIndex   lt endIndex            Usage  var str    quot Hello  Nick Michaels quot  print str subString from 7 to 20      print Nick Michaels

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You should leave one side empty  hence the name  partial range    let newStr   str    lt index    The same stands for partial range from operators  just leave the other side empty   let newStr   str index       Keep in mind that these range operators return a Substring  If you want to convert it to a string  use String s initialization function   let newStr   String str    lt index     You can read more about the new substrings here

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This is my solution  no warning  no errors  but perfect  let redStr  String   String trimmStr String Index init encodedOffset  0    lt String Index init encodedOffset  2    let greenStr  String   String trimmStr String Index init encodedOffset  3    lt String Index init encodedOffset  4    let blueStr  String   String trimmStr String Index init encodedOffset  5    lt String Index init encodedOffset  6

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with this method you can get specific range of string you need to pass start index and after that total number of characters you want   extension String      func substring fromIndex   Int count   Int  - gt  String          let startIndex   self index self startIndex  offsetBy  fromIndex          let endIndex   self index self startIndex  offsetBy  fromIndex   count          let range   startIndex   lt endIndex         return String self range

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Convert Substring  Swift 3  to String Slicing  Swift 4   Examples In Swift 3  4   let newStr   str substring to  index     Swift 3 let newStr   String str    lt index      Swift 4     let newStr   str substring from  index     Swift 3 let newStr   String str index         Swift 4      let range   firstIndex   lt secondIndex    If you have a range let newStr     str substring with  range     Swift 3 let newStr   String str range       Swift 4

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Shorter in Swift 4 5   var string    123456  string   String string prefix 3      123  string   String string suffix 3      456

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Hope it would be helpful   extension String       func getSubString   char  Character  - gt  String           var subString              for eachChar in self               if eachChar    char                   return subString               else                   subString    String eachChar                                  return subString           let str  String    Hello  playground  print str getSubString

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The conversion of your code to Swift 4 can also be done this way      let str    Hello  playground  let index   str index of        let substr   str prefix upTo  index    You can use the code below to have a new string   let newString   String str prefix upTo  index

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Swift 5  4 Usage let text    quot Hello world quot  text 0     H text    3      quot Hell quot  text 6   lt text count     world text NSRange location  6  length  3      wor  Code import Foundation  public extension String     subscript value  Int  - gt  Character       self index at  value          public extension String     subscript value  NSRange  - gt  Substring       self value lowerBound   lt value upperBound         public extension String     subscript value  CountableClosedRange lt Int gt   - gt  Substring       self index at  value lowerBound    index at  value upperBound          subscript value  CountableRange lt Int gt   - gt  Substring       self index at  value lowerBound    lt index at  value upperBound          subscript value  PartialRangeUpTo lt Int gt   - gt  Substring       self    lt index at  value upperBound          subscript value  PartialRangeThrough lt Int gt   - gt  Substring       self    index at  value upperBound          subscript value  PartialRangeFrom lt Int gt   - gt  Substring       self index at  value lowerBound             private extension String     func index at offset  Int  - gt  String Index       index startIndex  offsetBy  offset

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Example of uppercasedFirstCharacter convenience property in Swift3 and Swift4   Property uppercasedFirstCharacterNew demonstrates how to use String slicing subscript in Swift4   extension String       public var uppercasedFirstCharacterOld  String         if characters count  gt  0            let splitIndex   index after  startIndex           let firstCharacter   substring to  splitIndex  uppercased            let sentence   substring from  splitIndex           return firstCharacter   sentence         else            return self                  public var uppercasedFirstCharacterNew  String         if characters count  gt  0            let splitIndex   index after  startIndex           let firstCharacter   self    lt splitIndex  uppercased            let sentence   self splitIndex              return firstCharacter   sentence         else            return self                 let lorem    lorem  uppercasedFirstCharacterOld print lorem     Prints  Lorem   let ipsum    ipsum  uppercasedFirstCharacterNew print ipsum     Prints  Ipsum

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substring from  index   Converted to   index      Check the sample  let text    1234567890  let index   text index text startIndex  offsetBy  3   text substring from  index      4567890     Swift 3  String text index               4567890     Swift 4

[swift] How can I use String substring in Swift 4? 'substring(to:)' is deprecated: Please use String slicing subscript with a 'partial range from' operator

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