如何在此NSString中使用NSRange？

Question

I have the following NSString :

productID = @"com.sortitapps.themes.pink.book";

At the end, "book" can be anything.... "music", "movies", "games", etc.

I need to find the third period after the word pink so I can replace that last "book" word with something else. How do I do this with NSRange? Basically I need this:

partialID = @"com.sortitapps.themes.pink.";

Answer 1

You can try a backward search for the dot and use the result to get the desired range:

NSString *str = @"com.sortitapps.themes.pink.book";
NSUInteger dot = [str rangeOfString:@"." options:NSBackwardsSearch].location;

NSString *newStr =
   [str stringByReplacingCharactersInRange:NSMakeRange(dot+1, [str length]-dot-1)
                                withString:@"something_else"];

Answer 2

Well, although this isn't a generic solution for finding characters, in your particular case you can "cheat" and save code by doing this:

[productID stringByDeletingPathExtension];

Essentially, I'm treating the name as a filename and removing the last (and only the last) extension using the NSString method for this purpose.

Answer 3

您可以使用-[NSString componentsSeparatedByString:@"."]拆分成组件，使用所需的值创建一个新数组，然后使用[NSArray componentsJoinedByString:@"."]将修改后的数组再次连接到一个字符串中。