Suppose I have a string "10.9.1.1", I want to get substring "10.9". How can I achieve this? So far I have the following:
var str = "10.9.1.1" let range = str.rangeOfString(".",options: .RegularExpressionSearch)! let rangeOfDecimal = Range(start:str.startIndex,end:range.endIndex) var subStr = str.subStringWithRange(rangeOfDecimal) But this will only return 10.
Actually your code returns "1" only, because "." in a regular expression pattern matches any character.
The correct pattern would be
\d+ one ore more digits \. a literal dot \d+ one or more digits In a Swift string, you have to escape the backslashes as "\\":
let str = "10.9.1.1" if let range = str.rangeOfString("\\d+\\.\\d+",options: .RegularExpressionSearch) { let subStr = str.substringWithRange(range) println(subStr) // "10.9" } 
