Open pdf/doc/xls in other iphone app with modification acknowledgment

I know how to implement inter-app communication. I did it with some examples.

Now I need to send/share a doc/xls file with other application in my iPad/iPhone that have url schemes to open in such files.

Questions

1. How Can I find the list of application that has url schemes to open such files.
2. How can I limit the open-in in some specified application with in the above list.

Important

1. How can I prevent the shared document from further sharing (such as email/print).
2. And if the shared file is modified by that application how can I know it.
3. How can I get back the shared file after modification.
4. While sharing is there 开发者_开发知识库is any option to make it as read-only,read-write privilege.

• In general, it is impossible to prevent a document from being shared. You can only make it more frustrating.

• Everything else depends on the URL scheme you are using. For example, if it is the file:// scheme then access is controlled by the OS and filesystem. If it is the http:// scheme then access is controlled by the HTTP server, etc.