Regular Expressions 101

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"
^http(s)?://([\w.-])+(/[\w ./?%&=-]+)*$
"
gm
^ asserts position at start of a line
http
matches the characters http literally (case sensitive)
1st Capturing Group
(s)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
s matches the character s with index 11510 (7316 or 1638) literally (case sensitive)
://
matches the characters :// literally (case sensitive)
2nd Capturing Group
([\w.-])+
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
Match a single character present in the list below
[\w.-]
\w matches any word character (equivalent to [a-zA-Z0-9_])
.-
matches a single character in the list .- (case sensitive)
3rd Capturing Group
(/[\w ./?%&=-]+)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
Match a single character present in the list below
[\w ./?%&=-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\w matches any word character (equivalent to [a-zA-Z0-9_])
./?%&=-
matches a single character in the list ./?%&=- (case sensitive)
$ asserts position at the end of a line
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.

Regular Expression
No Match

r"
"
gm

Test String

Code Generator

Generated Code

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Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report.
For a full regex reference for Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression