Objective-c NSData转NSString后为nil 的解决办法

Apple官方的文档:

​​Return Value​​

​​An NSString object initialized by converting the bytes ​​​ ​​​in​​​  ​​​data into Unicode characters using encoding. The returned object may be different from the original receiver. Returns nil ​​​ ​​​if​​​  ​​​the initialization fails ​​​ ​​​for​​​  ​​​some reason (​​​ ​​​for​​​  ​​​example ​​​ ​​​if​​​  ​​​data does not represent valid data ​​​ ​​​for​​​  ​​​encoding).​​

返回nil很可能是编码问题, 有可能你的页面里混入了非utf8的字符

解决办法: 

用libiconv清除非utf8字符

先给项目Link Binaries With Library 添加libiconv.dylib

#include "iconv.h"
 
- (NSData *)cleanUTF8:(NSData *)data {
  iconv_t cd = iconv_open("UTF-8", "UTF-8"); // 从utf8转utf8
  int one = 1;
  iconvctl(cd, ICONV_SET_DISCARD_ILSEQ, &one); // 丢弃不正确的字符
 
  size_t inbytesleft, outbytesleft;
  inbytesleft = outbytesleft = data.length;
  char *inbuf  = (char *)data.bytes;
  char *outbuf = malloc(sizeof(char) * data.length);
  char *outptr = outbuf;
  if (iconv(cd, &inbuf, &inbytesleft, &outptr, &outbytesleft)
      == (size_t)-1) {
    NSLog(@"this should not happen, seriously");
    return nil;
  }
  NSData *result = [NSData dataWithBytes:outbuf length:data.length - outbytesleft];
  iconv_close(cd);
  free(outbuf);
  return result;
}