CODEWITHSUNDEEP
iosiphoneipadfilesystems
f2prateek
f2prateek

Reputation: 2084

iOS Private Directory

I'm wondering if this snippet of code returns a directory that is private to an application and protected by the application sandbox.

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES);
return [paths firstObject];

To test this myself, I wrote two applications. Application prateek.writer runs the following piece of code:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES);
NSString *applicationSupportDirectory = [paths firstObject];
NSLog(@"applicationSupportDirectory: '%@'", applicationSupportDirectory); // This is used by the second app.

NSString *filePath = [applicationSupportDirectory stringByAppendingPathComponent:@"myfile.txt"];

if (![[NSFileManager defaultManager] fileExistsAtPath:applicationSupportDirectory
                                              isDirectory:NULL]) {
  NSError *error = nil;
  if (![[NSFileManager defaultManager] createDirectoryAtPath:applicationSupportDirectory
                                       withIntermediateDirectories:YES
                                                        attributes:nil
                                                             error:&error]) {
            NSLog(@"error %@", error);
  }
}

[@"Hello World" writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];

The second application, prateek.reader, runs the following piece of code:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSUserDomainMask, YES);
// This string is copied from the logs of the writer application.
NSString *applicationSupportDirectory = @"/Users/prateek/Library/Developer/CoreSimulator/Devices/218F1365-5AF2-4003-83AF-6337E0EA8207/data/Containers/Data/Application/B8918247-5509-458D-AB9E-0F1273EAD2FE/Library/Application Support";

NSString *filePath = [applicationSupportDirectory stringByAppendingPathComponent:@"myfile.txt"];

NSString *string = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
NSLog(@"Read file with contents: %@", string);

My reader app was able to read the data from the writer app. I ran this on an iPhone 8 Plus and iPad Air simulator and saw the same results. Could it maybe have something to do with this being simulator, or the fact that these are apps created/signed by the same developer (me in this case).

Upvotes: 0

Views: 1412

Answers (1)

rmaddy
rmaddy

Reputation: 318794

The Application Support folder is specific to each app and is within an app's private sandbox. No app can access this folder of another app, when run on a real iOS device.

The simulator has no such limitations. It's one of the many differences between running on a real device and a simulator.

Upvotes: 1

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