Issue with encoding objects on iOS Device - ios

Question

I'm making an app that uses encoding to store objects on the document directory,
On iOS Simulator, the objects are getting saved perfectly, and if i closed the app and got back to it all the data are restored with no issue.
But today i tried my app on the iPhone 5s, the objects are not getting saved when i close the app and go back to it again all the data are getting removed only on the real device, what is the problem ?
I'm using this method to get the directory path:
- (NSString *)pathForTask
{
NSArray *documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentDirectory = [documentDirectories firstObject];
return [documentDirectory stringByAppendingString:#"Tasks"];
}
Archive:
NSString *path = [self pathForTask];
[NSKeyedArchiver archiveRootObject:self.privateTasks toFile:path];
Unarchive:
NSString *path = [self pathForTask];
_privateTasks = [NSKeyedUnarchiver unarchiveObjectWithFile:path];

Answer 1

The following line of code is causing your problem:
return [documentDirectory stringByAppendingString:#"Tasks"];
The results in the returned path being something like:
.../DocumentsTasks
Note the lack of a slash.
Change the line to:
return [documentDirectory stringByAppendingPathComponent:#"Tasks"];
This will return a proper path and your code will work on a device.
It works in the simulator because you end up creating a file named DocumentTasks in some folder on your computer. But on a real device, the folder that this file is trying to be written to is read-only due to sandboxing.

Answer 2

Try getting the documents directory using the following code instead:
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
After getting the documents directory, you can get the path to a specific file by doing:
NSURL *fileURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"[FILE NAME]"];
I'm not sure why your code doesn't work, but this is the code I use on my app and it works in the simulator and the physical device.

Answer 3

Frequently code that works on the sim but not on the device is caused by filename upper/lower case mismatching.
The file system in Mac OS is almost always case-insenstive. (You can use disk volumes who's file system are case sensitive in Mac OS, but they are not by default.)
The simulator runs on Mac OS. It's file system is not case sensitive. So if you save a file as "Tasks" and then load it as "tasks" it works on the sim, but not on an actual iOS device. Make sure you check really carefully for mismatched case in your filenames.