regular expressions replace in iOS - ios

Question

I am going to need to replace a dirty string for a clean string:
-(void)setTheFilter:(NSString*)filter
{
[filter retain];
[_theFilter release];
<PSEUDO CODE>
tmp = preg_replace(#"/[0-9]/",#"",filter);
<~PSEUDO CODE>
_theFilter = tmp;
}
This should eliminate all numbers in the filter so that:
#"Import6652"
would yield #"Import"
How can I do it in iOS ?
Thanks!

Answer 1

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:
#"([0-9]+)" options:0 error:nil];
[regex replaceMatchesInString:str options:0 range:NSMakeRange(0, [str length]) withTemplate:#""];
Swift
do {
let regex = try NSRegularExpression(pattern: "([0-9]+)", options: NSRegularExpressionOptions.CaseInsensitive)
regex.replaceMatchesInString(str, options: NSMatchingOptions.ReportProgress, range: NSRange(0,str.characters.count), withTemplate: "")
} catch {}

Answer 2

See the docs for NSRegularExpression
In particular the section titled Replacing Strings Using Regular Expressions

Answer 3

String replacing code using regex
Swift3
extension String {
func replacing(pattern: String, withTemplate: String) throws -> String {
let regex = try RegularExpression(pattern: pattern, options: .caseInsensitive)
return regex.stringByReplacingMatches(in: self, options: [], range: NSRange(0..<self.utf16.count), withTemplate: withTemplate)
}
}
use
var string: String = "Import6652"
do {
let result = try string.replacing(pattern: "[\\d]+", withTemplate: "")
} catch {
// error
}

Answer 4

in iOS 4.0+, you can use NSRegularExpression:
Use matchesInString:options:range: to get an array of all the matching results.
and then delete them from original string

Answer 5

Though not via a regular expression but you can use stringByTrimmingCharactersInSet
stringByTrimmingCharactersInSet:
Returns a new string made by removing from both ends of the receiver characters contained in a given
character set.
in combination with
decimalDigitCharacterSet
Returns a character set containing the characters in the category of Decimal Numbers.
like this:
[filter stringByTrimmingCharactersInSet:[NSCharacterSet decimalDigitCharacterSet]];
Caveat: it will only remove the characters at both ends.