Question

如何去掉字符串的前后TAB键和回车键

Answer 1

在objective-c中，如何去掉一个string 的前后的空格字符或某个特定字符呢？
如@ “ abc 123 ”字符串前后有空格，该如何去掉？
使用nsstring 的实例方法stringByTrimmingCharactersInSet ：可以解决该问题。
方法如下：
C代码 收藏代码
[@" abc 123 " stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]；

NSString *newString = [oldString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

NSString 中该方法说明如下：
stringByTrimmingCharactersInSet:
Returns a new string made by removing from both ends of the receiver characters contained in a given character set.
- (NSString *)stringByTrimmingCharactersInSet:(NSCharacterSet *)set
Parameters
set
A character set containing the characters to remove from the receiver. set must not be nil .
Return Value
A new string made by removing from both ends of the receiver characters contained in set . If the receiver is composed entirely of characters from set , the empty string is returned.

这是典型的其他语言中trim 方法。我要问的是，如何去掉最左边的空格？又该如何去掉最右边的空格？
在NSString 的类中没有提供实现这类需求的方法，我们只能手工去添加这些方法。