Last time, in
Part 1 of this series, I wrote about the basics of regular
expressions, and the phrases I tend to use. Today, I’m going to talk about the
mechanics of how I use Regular Expressions in Cocoa.
##But first, an historical diversion
In my opinion there are, two different ways that programming languages
implement Regular Expressions: The perl/ruby way, and the Java/C#/Python/Cocoa
way.
In ruby and perl, regexes are implemented directly on the String type, whereas
in the other languages, there a separate object that contains the
functionality. Here’s what you need to know to do a regex substitution on a
string in ruby:
myString.sub(‘pattern’,‘replacement’)
clean, easy, and immediately useable if you know what pattern you want to use.
Here’s what you need to know to do the same thing in Cocoa:
+[NSRegularExpression regularExpressionWithPattern:(NSString *) pattern
options:(NSRegularExpressionOptions)options error:(NSError **) error]
-[NSRegularExpression replaceMatchesInString:(NSMutableString *) string
options:(NSMatchingOptions)options range:(NSRange)range
withTemplate:(NSString *)template]
which is not clean, not easy and contains a bunch of stuff you have to go look
up to be able to get started. What are
NSRegularExpressionOptions and
NSMatchingOptions? What’s a
template? Do I
really have to create an
NSRange for this? And that leads to the obvious question:
Is all this
effort really worth it?
Now I don’t know about you, but I don’t want to spend any effort remembering
any of those option parameters, and I don’t want to take the time to look them
up any time I want to use a regular expression. To me, the beauty of
Objective-C is that it gives us the ability to build most of what you need to
know directly into the method signatures.
Published at October 15, 2011 ·
7 min read
