StringBetweenString function

Question

I need to get substring between two strings from my text. For example, I have text "http://google.com" and I want to get substring between "://" and ".".

I don't know, how I can do that.

I try to use regular expressions, but I think, it's bad way.

Answer 1

A couple of options:

1. Regular expressions work well. See ICU User Guide: Regular Expressions

   Example:

   let us = "http://google.com"
   let range = us.rangeOfString("(?<=://)[^.]+(?=.)", options:.RegularExpressionSearch)
   if range != nil {
       let found = us.substringWithRange(range!)
       println("found: \(found)") // found: google
   }
   

   Notes:

       (?<=://) means preceded by ://  
       [^.]+    means any characters except .  
       (?=.)    means followed by .  
   

2. NSScanner is also a good method. See Apple's NSScanner Class Reference

   Example:

   let us = "http://google.com"
   let scanner = NSScanner(string:us)
   var scanned: NSString?
   
   if scanner.scanUpToString("://", intoString:nil) {
       scanner.scanString("://", intoString:nil)
       if scanner.scanUpToString(".", intoString:&scanned) {
           let result: String = scanned as String
           println("result: \(result)") // result: google
       }
   }
   

Answer 2

You can use the regular Expression

://.+.

it matches to

://google.

in this code:

var yourURL: NSString = "http://google.com" // this is your input and could be any URL
var regex: NSRegularExpression = NSRegularExpression.regularExpressionWithPattern("://.+\\.", options: NSRegularExpressionOptions.fromMask(UInt(0)), error: nil) // need double backspace because of backspace in String is \\ not \
var needleRange = regex.rangeOfFirstMatchInString(yourURL, options:NSMatchingOptions.Anchored, range: NSMakeRange(0, yourURL.length))
var needle: NSString = yourURL.substringWithRange(needleRange)

Now you can remove the first 3 symbols and the last one and you got

google

with this code:

import Foundation

var halfURL: NSString = "://google."
var prefix: NSString = "://"
var suffix: NSString = "."
var needleRange: NSRange =  NSMakeRange(prefix.length, halfURL.length - prefix.length -     suffix.length)
var needle: NSString = halfURL.substringWithRange(needleRange)
// needle is now 'google'