如何在带有NSRegularExpression的Objective-C中正确进行反向引用？

Question

In PHP I'd do something like this:

But in Objective-C, I tried this:

    regex = [NSRegularExpression regularExpressionWithPattern:@"\\.([a-zA-Z0-9])" options:NSRegularExpressionCaseInsensitive error:&error];
    result = [regex stringByReplacingMatchesInString:result options:0 range:NSMakeRange(0, [result length]) withTemplate:@". \1"];

But it ends up simply removing the first letter of the next sentence (such as "end. Chris" -> "end. hris"). Why is this?

Answer 1

Use $1 , $2 , etc. instead of \\1 , \\2 , etc. for back references.

See the docs for NSRegularExpression . Look under the "Template Matching Format" section.