iOS learning iOS sandbox (sandbox) mechanism and file operations (i)

1. iOS sandbox mechanism

iOS applications can only read files in the file system created for the program, not access to other places, this area is a sandbox, so all non-code files to be stored in this, such as icons, sounds, images, attributes list, text files and so on.

1.1. Each application has its own storage space

1.2, the application can not turn over their walls to access the contents of other storage space

1.3, the application requests the data to pass the permission detection, if does not meet the condition, will not be released.

This diagram can only be understood from the surface of the sandbox is a security system, all the operations of the application through the system to execute, the core content is: Sandbox the application to perform various operations of the permission restrictions.

2. Open the emulator sandbox directory

Here's a look at where the emulator's sandbox folder is on your Mac computer.

The files are in a hidden folder under the personal User name folder, the Chinese is called the Repository, his directory is actually the library.

2.1 Method 1, you can set the display hidden files, and then open directly under the Finder. Here's how to set up viewing hidden files: Open terminal, enter name

command to display Mac hidden files: Defaults write Com.apple.finder appleshowallfiles-bool true

command to hide Mac hidden files: Defaults write Com.apple.finder Appleshowallfiles-bool false

After you lose, click Enter to exit the terminal,

Restart Finder: Click the Apple icon in the upper-left corner of the window to force exit-->finder-->

You can now see the repository folder.

Locate the/application Support/iphone simulator/folder after opening the repository. This is the sandbox directory of the simulator's various programs.

2.2 Method 2, this method is more convenient, on the Finder point-to go to the folder, enter/users/username/library/application Support/iphone simulator/to go.

Username here to write your user name.

3. Directory structure

By default, each sandbox contains 3 folders: Documents, Library, and TMP. Applications can only read and write files in several directories because of the sandboxed mechanism applied

Documents: Apple recommends that file data that is created in the program or browsed in the program be saved in this directory, which is included in itunes backup and restore

Library: The default settings or other status information of the stored program;

Library/caches: Store cached files, itunes does not back up this directory, files in this directory will not be deleted in the app exit

TMP: Provides a place to create temporary files on the fly.

itunes backs up all documents and library files while syncing with the iphone.

When the iphone restarts, all of the TMP files are discarded.

We create a Iossandbox project to expand the practice of sandbox and file read and write operations.

After creation, locate the corresponding directory on the emulator,

This is the catalogue all expanded.

Here are the three directories mentioned above: Documents, Library, tmp