去除 username中的空格，table newline，nextline
代碼如下：（三行代碼）
NSCharacterSet *whitespace = [NSCharacterSet? whitespaceAndNewlineCharacterSet];
NSString * username = [mUsernameField? stringValue];
示例
username = [username? stringByTrimmingCharactersInSet:whitespace];
NSString *temptext = [messageTextField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSString *text = [temptext stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet ]];
第1行是去除2端的空格
第2行是去除回車
//自定義想要去除的字符
在iOS中 ??可以使用stringByTrimmingCharactersInSet函數過濾字符串中的特殊符號
首先自己定義一個NSCharacterSet, 包含需要去除的特殊符號
NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@"@／：；（）￥「」＂、[]{}#%-*+=_\\|~＜＞$€^?'@#$%^&*()_+'\""];
由于NSString中有全角符號和半角符號, 因此有些符號要包括全角和半角的
然后調用stringByTrimmingCharactersInSet
NSString *trimmedString = [string stringByTrimmingCharactersInSet:set];
trimmedString就是過濾后的字符串
\注釋
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 替換 whitespaceAndNewlineCharacterSet 區別newline nextline
whitespaceCharacterSet
Returns a character set containing only the in-line whitespace characters space (U+0020) and tab (U+0009).
