我封装好了2个方法，用来字典和data相互转换的，直接复制方法拿来用就可以了，注意2点：
1.我是用的mrc，用arc的同学把autorelease去掉即可。
2.第二个我是路径文件转的字典，想data转的话自己把方法改一下就行了。
//字典转data
+(NSData *)returnDataWithDictionary:(NSDictionary *)dict
{
NSMutableData * data = [[NSMutableData
alloc]
init];
NSKeyedArchiver * archiver = [[NSKeyedArchiver
alloc] initForWritingWithMutableData:data];
[archiver
encodeObject:dict
forKey:@"talkData"];
[archiver
finishEncoding];
[data
autorelease];
[archiver
autorelease];
return data;
}
//路径文件转dictonary
+(NSDictionary *)returnDictionaryWithDataPath:(NSString *)path
{
NSData * data = [[NSMutableData
alloc] initWithContentsOfFile:path];
NSKeyedUnarchiver * unarchiver = [[NSKeyedUnarchiver
alloc]
initForReadingWithData:data];
NSDictionary * myDictionary = [[unarchiver
decodeObjectForKey:@"talkData"]
retain];
[unarchiver
finishDecoding];
// NSLog(@"%@", myDictionary);
[unarchiver
autorelease];
[data
autorelease];
return myDictionary;
}