NSString 往首尾空格

NSString 去首尾空格
    NSString* str = @"   hello world !   ";  
    str = [str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];  
    NSLog(@"[%@]", str);


函数原型
    - (NSString *)stringByTrimmingCharactersInSet:(NSCharacterSet *)set