split string into array with a common regx

Question

In Swift I have a string like:

let str = "5~895893799,,6~898593679,,7~895893679,,8~895893799,,5~895893799,,6~898593679,,7~895893679,,8~895893799";

From this I need to get only the number which is before "~" which is [5,6,7,8,5,6,7,8]

How can I achieve this?

actual string is "5~895893799,,6~898593679,,7~895893679,,8~895893799,,5~895893799,,6~898593679,,7~895893679,,8~895893799" — Bharath
– Bharath, Commented Jul 20, 2019 at 22:14
Please post a snippet of code which is your best guess to solve this problem and ask for help to improve it. — BobHy
– BobHy, Commented Jul 20, 2019 at 22:42

rmaddy · Accepted Answer · 2019-07-20 22:28:53Z

3

Make use of components(separatedBy:) and compactMap.

let str = "5~895893799,,6~898593679,,7~895893679,,8~895893799,,5~895893799,,6~898593679,,7~895893679,,8~895893799"
let nums = str.components(separatedBy: ",,")
              .compactMap { $0.components(separatedBy: "~").first }

That gives the string array:

["5", "6", "7", "8", "5", "6", "7", "8"]

If you want an array of Int, add:

.compactMap { Int($0) }

to the end.

let nums = str.components(separatedBy: ",,")
              .compactMap { $0.components(separatedBy: "~").first }
              .compactMap { Int($0) }

That gives:

[5, 6, 7, 8, 5, 6, 7, 8]

answered Jul 20, 2019 at 22:28

rmaddy

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Comments

ielyamani · Accepted Answer · 2019-07-21 08:01:43Z

You could define this regular expression:

let regex = try! NSRegularExpression(pattern: #"\d+(?=~)"#)

\d : matches any digit
+ : this is the one or more quantifier
(?=~) : Positive lookahead for "~"

and use it like so:

let range = NSRange(location: 0, length: (str as NSString).length)
let matches = regex.matches(in: str, range: range)

let strings: [String] = matches.map { match in
    let subRange = match.range
    let startIndex = str.index(str.startIndex, offsetBy: subRange.lowerBound)
    let endIndex = str.index(str.startIndex, offsetBy: subRange.upperBound)
    let subString = String(str[startIndex..<endIndex])

    return subString
}

let numbers = strings.compactMap(Int.init)  //[5, 6, 7, 8, 5, 6, 7, 8]

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