Regular Expression in iOS

How do you write regular expressions for a valid username for swift?

^\w{1,13}$

^ beginning of string anchor

\w word character - any letter (including UTF-8), any case, 0-9 and underscore

{1,13} length between 1 and 13, inclusive

$ end of string anchor

https://regex101.com/ - good resource

How to write regular expression with global search in iOS?

what is \g in regex? try @"[^A-Z]" or @"[^A-Z]+" with options 0:

in iOS using regex to search or replace is really greedy, searching or replacing scopes is depend on range in regex function's parameters.

NSError *error = nil;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"[^A-Z]" options:0 error:&error]; // or @"[^A-Z]+"

NSString *UF = [regex stringByReplacingMatchesInString:@"New York" options:0 range:NSMakeRange(0, [@"New York" length]) withTemplate:@""];

Swift Regex with special Characters

The problem is that characters [, \, and ] need to be escaped because they have special meaning in a regular expression.

So you need \[, \\, and \] in the regular expression. But since this is inside a Swift string, each \ needs to be escaped with a \.

So [\] becomes \[\\\] in the regular expression which becomes \\[\\\\\\] in the Swift string.

The final valid string is:

var passwordRegex = "^[A-Za-z0-9 !\"#$%&'()*+,-./:;<=>?@\\[\\\\\\]^_`{|}~].{8,}$"

swift Regular Expression and (.*?)

Your exec code contains .IgnoreMetacharacters flag:

Treat the entire pattern as a literal string.

Remove it so that the pattern could be treated as a regex pattern.

Also, a good idea is to use a DOTALL modifier (?s) at the start of the pattern.

Also, remember that a dot matches any character, escape it to match a literal dot.

As for the pattern, I'd recommend

"(?s)ytplayer\\.config = \\{(.*?)\\};"

Or a much faster:

"(?s)ytplayer\\.config = \\{([^}]*(?:\\}(?!;)[^}]*)*)\\};"

See the regex demo

How to Split String With Regular Expression ios objectivec

You may first replace all the matches with a non-used symbol, say, with \x00 null char, and then split with it:

NSError *error = nil;
NSString *str = @"LR00001";
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?<=\\D)(?=\\d)" options:nil error:&error];
NSString *modifiedString = [regex stringByReplacingMatchesInString:str options:0 range:NSMakeRange(0, [str length]) withTemplate:@"\x00"];
NSArray *chunks = [modifiedString componentsSeparatedByString: @"\x00"];
for(NSString *c in chunks) {
    NSLog(@"%@", c);
}

It prints LR and 00001.

See the online demo.

Regular Expressions in ios(a word a letter and special characters)

Description

^(?=.*[a-z])(?=.*[0-9])[a-z0-9!@$&#]*$

This regular expression will do the following:

• (?=.*[a-z]) Require the string to contain at least one a-z character
• (?=.*[0-9]) Require the string to contain at least one 0-9 character
• [a-z0-9!@$&#]*$ Allow the string to be made up of only a-z characters, 0-9 characters, and !@$&# symbols

Example

Live Demo

https://regex101.com/r/mC3kL3/1

Explanation

NODE                     EXPLANATION
----------------------------------------------------------------------
  ^                        the beginning of a "line"
----------------------------------------------------------------------
  (?=                      look ahead to see if there is:
----------------------------------------------------------------------
    .*                       any character except \n (0 or more times
                             (matching the most amount possible))
----------------------------------------------------------------------
    [a-z]                    any character of: 'a' to 'z'
----------------------------------------------------------------------
  )                        end of look-ahead
----------------------------------------------------------------------
  (?=                      look ahead to see if there is:
----------------------------------------------------------------------
    .*                       any character except \n (0 or more times
                             (matching the most amount possible))
----------------------------------------------------------------------
    [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  )                        end of look-ahead
----------------------------------------------------------------------
  [a-z0-9!&#]*             any character of: 'a' to 'z', '0' to '9',
                           '!', '&', '#' (0 or more times (matching
                           the most amount possible))
----------------------------------------------------------------------
  $                        before an optional \n, and the end of a
                           "line"
----------------------------------------------------------------------

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