解决方法
iOS 5现在拥有了所需的一切：
NSError *error = nil;
NSOutputStream *outputStream = [NSOutputStream outputStreamToFileAtPath:filepath append:yesOrNo];
[outputStream open];
[NSJSONSerialization writeJSONObject:nsDicOrNSArrayObject
toStream:outputStream
options:0
error:&error];
[outputStream close];
