Collapse sequences of white space into a single character and trim string

Question

Consider the following example:

"    Hello      this  is a   long       string!   "

I want to convert that to:

"Hello this is a long string!"

Answer 1

OS X 10.7+ and iOS 3.2+

Use the native regexp solution provided by hfossli.

Otherwise

Either use your favorite regexp library or use the following Cocoa-native solution:

NSString *theString = @"    Hello      this  is a   long       string!   ";

NSCharacterSet *whitespaces = [NSCharacterSet whitespaceCharacterSet];
NSPredicate *noEmptyStrings = [NSPredicate predicateWithFormat:@"SELF != ''"];

NSArray *parts = [theString componentsSeparatedByCharactersInSet:whitespaces];
NSArray *filteredArray = [parts filteredArrayUsingPredicate:noEmptyStrings];
theString = [filteredArray componentsJoinedByString:@" "];