先上个例子：
NSString * str1 =[nameInput.text stringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceAndNewlineCharacterSet]];
NSString * str2 =[passwdInput.text stringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceAndNewlineCharacterSet]];
[self.delegate loginActionInView:self name:str1 passwd:str2];
转载自：http://blog.csdn.net/aiyongyyy/article/details/8269546
在iOS中 可以使用stringByTrimmingCharactersInSet函数过滤字符串中的特殊符号
首先自己定义一个NSCharacterSet, 包含需要去除的特殊符号
NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@"@／：；（）¥「」＂、[]{}#%-*+=_\|~＜＞$€^•'@#$%^&*()_+'""];
由于NSString中有全角符号和半角符号, 因此有些符号要包括全角和半角的
然后调用stringByTrimmingCharactersInSet
NSString *trimmedString = [string stringByTrimmingCharactersInSet:set];
trimmedString就是过滤后的字符串
----------------------------------------------------------
http://blog.sina.com.cn/s/blog_5421851501014xif.html
去除 username中的空格，table newline，nextline
代码如下：（三行代码）
NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
NSString * username = [mUsernameField stringValue];
username = [username stringByTrimmingCharactersInSet:whitespace];
注释：
stringByTrimmingCharactersInSet:
Returns a new string made by removing from both ends of the receiver characters contained in a given character set.
whitespaceAndNewlineCharacterSet
Returns a character set containing only the whitespace characters space (U+0020) and tab (U+0009) and the newline and nextline characters (U+000A–U+000D, U+0085).
另外可以用 whitespaceCharacterSet 替换 whitespaceAndNewlineCharacterSet 区别newline nextline
whitespaceCharacterSet
Returns a character set containing only the in-line whitespace characters space (U+0020) and tab (U+0009).
NSString *temptext = [messageTextField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSString *text = [temptext stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet ]];
使用stringByTrimmingRightCharactersInSet 方法去掉一个字符串最右边的空格。
- NSLog(@"%@",[@"abc 123 " stringByTrimmingRightCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]);
如何去掉一个字符串@ “0.012300 ”最右边的“0 “呢？这是典型的float 格式化成字符串以后的形式，显示时最好去掉最右边的“0 ”。
解决方法如下：
- [@"0.012300" stringByTrimmingRightCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"0"]]；