objectiveC中怎么获得所有的可用编码？

在Java中可以这样获取可用编码：

SortedMap<String, Charset> availableCharsets = Charset.availableCharsets();
Vector allEncodes = new Vector();
for (Map.Entry<String, Charset> entry : availableCharsets.entrySet()) {
            allEncodes.add(entry.getKey());
}

然后这样读取文件：

Reader in = new InputStreamReader(new FileInputStream(aPath), allEncodes.get(0) );

那么在objective-c中怎么实现类似的功能？

我给的代码有点类似Java.不过你要完善其中的readingError变量。核心代码是avaiableStringEncodings.

  NSMutableArray *arrayOfEncodings = [[NSMutableArray alloc] init];

  const NSStringEncoding *encodings = [NSString availableStringEncodings];
  while (*encodings != 0){
    [arrayOfEncodings addObject:[NSNumber numberWithInt:*encodings]];
    encodings++;
  }

  NSError *readingError = nil;
  NSString yourPath = @"some path you want";
  NSData *data = [[NSData alloc] initWithContentsOfFile:yourPath    options:NSDataReadingUncached error:&readingError];

  NSStringEncoding firstEncoding = (NSStringEncoding) [((NSNumber *) [arrayOfEncodings objectAtIndex:0]) intValue];

  NSString *myString = [[NSString alloc] initWithData:data encoding:firstEncoding]; 

const NSStringEncoding* encodingArray = [NSString availableStringEncodings];