IOS 字符串中去除特殊符号 stringByTrimmingCharactersInSet 应该用于账号登录等

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];

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

----------------------------------------------------------

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 ]];

第1行是去除2端的空格

第2行是去除回车