 <p>No, you are misunderstanding how that method works. <code>componentsSeparatedByString:</code> doesn't use the individual characters in the passed string, it uses the entire string. Your separator is the three-character sequence <code>[,]</code>. A string like <code>@"pecan[,]pie"</code> uses this separator, but <code>@"1[0,5]"</code> does not. The similar method <a href="http://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html#//apple_ref/doc/uid/20000154-SW5" rel="nofollow"><code>componentsSeparatedByCharactersInSet:</code></a> will do what you are expecting:</p> <pre><code>[string componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"[,]"]]; </code></pre> <p>If you want to pull digits out of strings and get their numerical values, you may want to look at <a href="http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Strings/Articles/Scanners.html" rel="nofollow"><code>NSScanner</code></a>.</p>