Swift Get string between 2 strings in a string
IosStringSwiftSubstringIos Problem Overview
I am getting a string from html parse that is;
string = "javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
my code is something like
var startIndex = text.rangeOfString("'")
var endIndex = text.rangeOfString("',")
var range2 = startIndex2...endIndex
substr= string.substringWithRange(range)
i am not sure if my second splitting string should be "'" or "',"
i want my outcome as
substr = "Info/99/something"
Ios Solutions
Solution 1 - Ios
extension String {
func slice(from: String, to: String) -> String? {
return (range(of: from)?.upperBound).flatMap { substringFrom in
(range(of: to, range: substringFrom..<endIndex)?.lowerBound).map { substringTo in
String(self[substringFrom..<substringTo])
}
}
}
}
"javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
.sliceFrom("'", to: "',")
Solution 2 - Ios
I'd use a regular expression to extract substrings from complex input like this.
Swift 3.1:
let test = "javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
if let match = test.range(of: "(?<=')[^']+", options: .regularExpression) {
print(test.substring(with: match))
}
// Prints: Info/99/something
Swift 2.0:
let test = "javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
if let match = test.rangeOfString("(?<=')[^']+", options: .RegularExpressionSearch) {
print(test.substringWithRange(match))
}
// Prints: Info/99/something
Solution 3 - Ios
I rewrote one of the top Swift answers to understand what it was doing with map. I prefer a version using guard, IMO.
extension String {
func slice(from: String, to: String) -> String? {
guard let rangeFrom = range(of: from)?.upperBound else { return nil }
guard let rangeTo = self[rangeFrom...].range(of: to)?.lowerBound else { return nil }
return String(self[rangeFrom..<rangeTo])
}
}
behavior:
let test1 = "a[b]c".slice(from: "[", to: "]") // "b"
let test2 = "abc".slice(from: "[", to: "]") // nil
let test3 = "a]b[c".slice(from: "[", to: "]") // nil
let test4 = "[a[b]c]".slice(from: "[", to: "]") // "a[b"
Solution 4 - Ios
To find all substrings that are between a starting string and an ending string:
extension String {
func sliceMultipleTimes(from: String, to: String) -> [String] {
components(separatedBy: from).dropFirst().compactMap { sub in
(sub.range(of: to)?.lowerBound).flatMap { endRange in
String(sub[sub.startIndex ..< endRange])
}
}
}
}
let str = "start A end ... start B end"
str.sliceMultipleTimes(from: "start", to: "end") // ["A", "B"]
Solution 5 - Ios
This works if it is always the second split:
let subString = split(string, isSeparator: "'")[1]
Solution 6 - Ios
You can use var arr = str.componentsSeparatedByString(",") as your second split which will return you array
Solution 7 - Ios
Swift 4.2:
extension String {
//right is the first encountered string after left
func between(_ left: String, _ right: String) -> String? {
guard let leftRange = range(of: left), let rightRange = range(of: right, options: .backwards)
,leftRange.upperBound <= rightRange.lowerBound else { return nil }
let sub = self[leftRange.upperBound...]
let closestToLeftRange = sub.range(of: right)!
return String(sub[..<closestToLeftRange.lowerBound])
}
}
Solution 8 - Ios
Consider using a regular expression to match everything between single quotes.
let string = "javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
let pattern = "'(.+?)'"
let regex = NSRegularExpression(pattern: pattern, options: nil, error: nil)
let results = regex!.matchesInString(string, options: nil, range: NSMakeRange(0, count(string))) as! [NSTextCheckingResult]
let nsstring = string as NSString
let matches = results.map { result in return nsstring.substringWithRange(result.range)}
// First match
println(matches[0])
Solution 9 - Ios
In Swift 4 or later you can create an extension method on StringProtocol to support substrings as well. You can just return a Substring instead of a new String:
edit/update: Swift 5 or later
extension StringProtocol {
func substring<S: StringProtocol>(from start: S, options: String.CompareOptions = []) -> SubSequence? {
guard let lower = range(of: start, options: options)?.upperBound
else { return nil }
return self[lower...]
}
func substring<S: StringProtocol>(through end: S, options: String.CompareOptions = []) -> SubSequence? {
guard let upper = range(of: end, options: options)?.upperBound
else { return nil }
return self[..<upper]
}
func substring<S: StringProtocol>(upTo end: S, options: String.CompareOptions = []) -> SubSequence? {
guard let upper = range(of: end, options: options)?.lowerBound
else { return nil }
return self[..<upper]
}
func substring<S: StringProtocol, T: StringProtocol>(from start: S, upTo end: T, options: String.CompareOptions = []) -> SubSequence? {
guard let lower = range(of: start, options: options)?.upperBound,
let upper = self[lower...].range(of: end, options: options)?.lowerBound
else { return nil }
return self[lower..<upper]
}
func substring<S: StringProtocol, T: StringProtocol>(from start: S, through end: T, options: String.CompareOptions = []) -> SubSequence? {
guard let lower = range(of: start, options: options)?.upperBound,
let upper = self[lower...].range(of: end, options: options)?.upperBound
else { return nil }
return self[lower..<upper]
}
}
Usage:
let string = "javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
let substr = string.substring(from: "'") // "Info/99/something', 'City Hall',1, 99);"
let through = string.substring(through: "Info") // "javascript:getInfo"
let upTo = string.substring(upTo: "Info") // "javascript:get"
let fromUpTo = string.substring(from: "'", upTo: "',") // "Info/99/something"
let fromThrough = string.substring(from: "'", through: "',") // "Info/99/something',"
let fromUpToCaseInsensitive = string.substring(from: "'info/", upTo: "/something", options: .caseInsensitive) // "99"
Solution 10 - Ios
Swift 5
extension String {
///Returns an empty string when there is no path.
func substring(from left: String, to right: String) -> String {
if let match = range(of: "(?<=\(left))[^\(right)]+", options: .regularExpression) {
return String(self[match])
}
return ""
}
}
Solution 11 - Ios
If you want to support also from the start or end of the string
extension String {
func slice(from: String, to: String) -> String? {
return (from.isEmpty ? startIndex..<startIndex : range(of: from)).flatMap { fromRange in
(to.isEmpty ? endIndex..<endIndex : range(of: to, range: fromRange.upperBound..<endIndex)).map({ toRange in
String(self[fromRange.upperBound..<toRange.lowerBound])
})
}
}
}
"javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
.slice(from: "'", to: "',") // "Info/99/something"
"javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
.slice(from: "", to: ":") // "javascript"
"javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
.slice(from: ":", to: "") // "getInfo(1,'Info/99/something', 'City Hall',1, 99);"
"javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
.slice(from: "", to: "") // "javascript:getInfo(1,'Info/99/something', 'City Hall',1, 99);"
if you want another syntax, maybe more readable
extension String {
func slice(from: String, to: String) -> String? {
guard let fromRange = from.isEmpty ? startIndex..<startIndex : range(of: from) else { return nil }
guard let toRange = to.isEmpty ? endIndex..<endIndex : range(of: to, range: fromRange.upperBound..<endIndex) else { return nil }
return String(self[fromRange.upperBound..<toRange.lowerBound])
}
}
Solution 12 - Ios
Swift 4 version of @litso. To find all values in text
func find(inText text: String, pattern: String) -> [String]? {
do {
let regex = try NSRegularExpression(pattern: pattern, options: .caseInsensitive)
let result = regex.matches(in: text, options: .init(rawValue: 0), range: NSRange(location: 0, length: text.count))
let matches = result.map { result in
return (text as NSString).substring(with: result.range)
}
return matches
} catch {
print(error)
}
return nil
}