去除NSString中的空字符

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

1.   去掉首尾的空字符

NSString *strResult = [theString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

 2、使用NSString *strUrl = [theString stringByReplacingOccurrencesOfString:@" " withString:@""];可以去掉空格，注意此时生成的strUrl是autorelease属性的，不要妄想对strUrl进行release操作。

    

3. 使用NSPredicate 筛选 去除 或者替换多余的

    NSCharacterSet *whitespaces = [NSCharacterSetwhitespaceCharacterSet];

    NSPredicate *noEmptyStrings = [NSPredicatepredicateWithFormat:@"SELF != ''"];

    

    NSArray *parts = [theString componentsSeparatedByCharactersInSet:whitespaces];

    NSArray *filteredArray = [parts filteredArrayUsingPredicate:noEmptyStrings];

    theString = [filteredArray componentsJoinedByString:@" "];  

// 1>  去除多余的 输出：Hello this is a long string!

// 2>     theString = [filteredArray componentsJoinedByString:@""];    完全去掉空格 输出：Hellothisisalongstring!

    NSLog(@"%@", theString);