NSFileHandle编写json数据格式

代码如下:

+ (void)writeToFile:(NSDictionary *)params filePath:(NSString *)path {
  NSData *jsonData = [self jsonToData:params];

  NSFileHandle *fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:path];
  if (fileHandle == nil) {
    NSLog(@"Failed to open file");
  }

  // 获取文件内容末尾的']'
  [fileHandle seekToFileOffset:[fileHandle seekToEndOfFile] - ];
  NSData *endData = [fileHandle readDataToEndOfFile];

  // 插入params
  [fileHandle seekToFileOffset:[fileHandle seekToEndOfFile] - ];
  [fileHandle writeData:jsonData];

  // 数组数据分割符
  NSData *diviData = [@"," dataUsingEncoding:NSUTF8StringEncoding];
  [fileHandle seekToEndOfFile];
  [fileHandle writeData:diviData];

  // 在文件内容末尾添加结束标识符']'
  [fileHandle seekToEndOfFile];
  [fileHandle writeData:endData];

  //关闭文件
  [fileHandle closeFile];
}

效果如图：