ios NSString 字符串常用方法

 

1.有时获取的网页编码是GB2312的，转换为UTF-8 格式代码：

NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);

NSString *retStr = [[NSString alloc] initWithData:data encoding:enc];

 

2.判断字符串是不是为空或者空白

- (BOOL)isEmptyOrWhitespace {
  // A nil or NULL string is not the same as an empty string
  return 0 == self.length ||
         ![self stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]].length;
}

3.url字符串编码

- (id)urlEncoded {
  CFStringRef cfUrlEncodedString = CFURLCreateStringByAddingPercentEscapes(NULL,
                                            (CFStringRef)self,NULL,
                                            (CFStringRef)@"!#$%&'()*+,/:;=?@[]",
                                            kCFStringEncodingUTF8);

  NSString *urlEncoded = [NSString stringWithString:(NSString *)cfUrlEncodedString];
  CFRelease(cfUrlEncodedString);
  return urlEncoded;
}

 4. NSString 转换为 NSData

- (NSData *)dataFormString:(NSString *)string
{
       if(!string) 
       {
             string = @"";
       }
       return [NSData dataWithBytes:[requestString UTF8String] length:strlen([requestString UTF8String])];
}