so I am the NSCachesDirectory to store the image data for the "x" most recent images a user has viewed. I would like to have NSCachesDirectory programmatically delete all files that exceed the total file count of "x".
I would like to do this such that the images added the earliest by time/date are deleted first. Is there a way to do this without actually knowing the name of the file I would like to delete? I know to delete a certain file I can just do the following:
NSArray *myPathList = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *mainPath = [myPathList objectAtIndex:0];
mainPath = [mainPath stringByAppendingPathComponent:DirectoryName];
and
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;
BOOL fileExists = [fileManager fileExistsAtPath:mainPath];
if (fileExists)
{
BOOL success = [fileManager removeItemAtPath:mainPath error:&error];
if (!success) NSLog(#"Error: %#", [error localizedDescription]);
}
but extending this to my use case has proven to be quite the challenge.
When you have some logic for the deletion of user cache data you better implement it for yourself, because you know best what to delete.
Apple File documentation for some details about storing files, with special attributes for backup.
Related
I am saving video/image in document directory.Now once the image is saved in document directory I want to save its reference in my local database.So I am thinking I can save URL of the image in the local database.
So is it constant throughout my app?
It's not constant, i have observed every time you launch the app it'll be different, but your data is moved to this new path. You can save your file name in your database, and dynamically append this file name to NSDocument directory.
- (NSString *)documentsFilePath:(NSString *)fileName {
NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsDir = [dirPaths firstObject];
NSString *filePath = [docsDir stringByAppendingPathComponent:fileName];
return filePath;
}
- (void)storeFile:(NSString *)fileName {
NSString *filePath = [self documentsFilePath:fileName];
// create if needed
if (![[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
// Write your data to file system here...
}
}
- (void)deleteFile:(NSString *)fileName {
NSString *filePath = [self documentsFilePath:fileName];
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
NSError *deleteErr = nil;
[[NSFileManager defaultManager] removeItemAtPath:filePath error:&deleteErr];
if (deleteErr) {
NSLog(#"Can't delete %#: %#", filePath, deleteErr);
}
}
}
Please handle nil checks and store only filename in DB
No, it's not constant. Whenever your app reinstall or updated on device the document directory will change, because when app installed on device os made an directory for app with some random id and each install this random it get changed by OS.
So, you need to make it dynamic own your own, like store the file name only and append the document directory path while using it.
I would suggest only saving the filename or subdirectory/filename (if you have a subdirectory) in the database and then only attaching that to the NSDocumentDirectory.
This will ensure that you always know where the file is...
NSDocumentDirectory is however consistent accross updates, so the files should remain in the document directory even if you update...
I am new to iOS development, I am making changes in an application which is using Sqlite. I am to add some new fields in some tables, I browsed DB with software and added new fields in
inventory_db_src.sqlite but when I see in emulator it uses inventory_db.sqlite which is strange as there is no inventory_db.sqlite file in solution and neither code creating DB through SQL script. And If I debug code it gets inventory_db.sqlite path successfully and never executes inventory_db_src.sqlite line and put inventory_db.sqlite in emulator where my new fields are not present as I put these in inventory_db_src.sqlite. pLease help me
BOOL success;
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *dbPath = [documentsDirectory stringByAppendingPathComponent:#"inventory_db.sqlite"];
// [fileManager removeItemAtPath:dbPath error:nil];
success = [fileManager fileExistsAtPath:dbPath];
success = NO;
if (success) {
int savedVersion = [[NSUserDefaults standardUserDefaults] integerForKey:kVERSION_KEY];
if (kCURRENT_DB_VERSION != savedVersion) {
[fileManager removeItemAtPath:dbPath error:nil];
success = NO;
}
}
if (!success) {
// The writable database does not exist, so copy the default to the appropriate location.
NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:#"inventory_db_src.sqlite"];
success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];
if (!success) {
NSAssert1(0, #"Failed to create writable database file with message '%#'.", [error localizedDescription]);
}
}
_INVENTORY_DB = [[FMDatabase alloc] initWithPath:dbPath];
Line 6 in your code above is showing the name as inventory_db.sqlite, so that is the file your app will be using. You need to modify that to use the new database name. Be aware, that by modifying your database, you might have unexpected results so you will need to manage what DB version your app is using and make data corrections as needed. This is one nice feature that Core Data can assist in.
According to your statement it seems that old DB is cached in to your Emulator. please reset you Emulator by
iOS Simulator -> Reset content and settings
And it should work ...
I am trying to write some image data to disk on iOS, but while it's working perfectly in the Simulator, when I try it on a real iPad it fails (returns 0).
BOOL success = [[NSFileManager defaultManager] createFileAtPath:filePath contents:imageData attributes:nil];
The path in question looks something like this: /Library/Caches/_0_0_0_0_1100_1149.jpg and I've also tried /Documents/....
Is there any way to actually get an error code or something beyond just success/fail?
The simulator does not simulate the sandboxing of the file system that is enforced on a device. You can write anywhere on the sim, but on a device writing anywhere but one of your designated directories will fail.
I'm guessing that your path is badly formed somehow. Try logging your path and the path you get from NSCachesDirectory (as shown in your second post.) They are almost certainly different.
Turns out you have to programmatically obtain the directory. The iOS file system is not sandboxed like I expected.
NSString* pathRoot = NSSearchPathForDirectoriesInDomains( NSCachesDirectory, NSUserDomainMask, YES )[0];
If you're writing image data, why not try writing via NSData's [writeToFile: options: error:] method, the "error" parameter for which can give you some really useful hints as to why your file isn't writing.
This is illogical:
if ( !( [ fileManager copyItemAtPath:resourceDBFolderPath toPath:documentDBFolderPath error:&error ]))
You are checking if the method exists, not if it succeeded!!
I have some relevant code I've used in my project, I hope it may be help you some way or another:
-(void)testMethod {
NSString *resourceDBFolderPath;
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;
NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory,
NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *documentDBFolderPath = [documentsDirectory stringByAppendingPathComponent:#"plans.gallery"];
BOOL success = [fileManager fileExistsAtPath:documentDBFolderPath];
if (success){
NSLog(#"Success!");
return;
}
else {
//simplified method with more common and helpful method
resourceDBFolderPath = [[NSBundle mainBundle] pathForResource:#"plans" ofType:#"gallery"];
//fixed a deprecated method
[fileManager createDirectoryAtPath:documentDBFolderPath withIntermediateDirectories:NO attributes:nil error:nil];
[fileManager copyItemAtPath:resourceDBFolderPath toPath:documentDBFolderPath
error:&error];
//check if destinationFolder exists
if ([ fileManager fileExistsAtPath:documentDBFolderPath])
{
//FIXED, another method that doesn't return a boolean. check for error instead
if (error)
{
//NSLog first error from copyitemAtPath
NSLog(#"Could not remove old files. Error:%#", [error localizedDescription]);
//remove file path and NSLog error if it exists.
[fileManager removeItemAtPath:documentDBFolderPath error:&error];
NSLog(#"Could not remove old files. Error:%#", [error localizedDescription]);
return;
}
}
}
}
I have a bunch of images stored in an images directory within my Supported Files directory in Xcode. I want to be able to show one of those images. What is the best way to obtain a path to that image? Do I have to copy them to the Documents directory first? If so, how can I do that?
EDIT: I've tried the following to copy the image from Supporting Files to the Documents folder in the app. It successfully copies, but I can't get the image to show:
-(void)findImage:(NSString *)imageName
{
// First, test for existence.
BOOL success;
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *appImagePath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.jpg",imageName]];
success = [fileManager fileExistsAtPath:appImagePath];
if (success)
{
return;
}
// The writable database does not exist, so copy the default to the appropriate location.
NSString *defaultImagePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.jpg",imageName]];
success = [fileManager copyItemAtPath:defaultImagePath toPath:appImagePath error:&error];
if (!success)
{
NSAssert1(0, #"Failed to create writable database file with message '%#'.", [error localizedDescription]);
}
self.imageDisplay.image = [UIImage imageNamed:appImagePath];
return;
}
This should do the trick:
[UIImage imageNamed:#"someImageName"];
EDIT:
Some additional information:
-imageNamed: will look through the entire main bundle of the application for an imagefile (preferrably an png) with the filename of "someImageName". You need not worry about its location or its extension, since it will be searched for in the mainbundle. Files that you import through the import-file-dialogue in xcode will be added to he main bundle.
This means:
If i have imported a file called myImage.png, calling [UIImage imageNamed:#"myImage"];from anywhere in my code will get me a UIImage-Object containing that image. Its amazingly simple, and maybe that startled you a bit ;)
Look it up in the docs if you like:
http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIImage_Class/Reference/Reference.html
NSFileManager* fileManager = [NSFileManager defaultManager];
NSURL* url = [[fileManager URLsForDirectory:NSCachesDirectory inDomains:NSUserDomainMask] lastObject];
NSString* directory = [url path];
NSString* filePath = [directory stringByAppendingPathComponent:FILE_NAME];
if ([fileManager fileExistsAtPath:filePath])
{
[fileManager removeItemAtPath:filePath error:nil];
}
Here's my code. When it is executed, the file is deleted, but the space remains occupied. Here's the code for storing something into the file.
NSFileManager* fileManager = [NSFileManager defaultManager];
NSURL* url = [[fileManager URLsForDirectory:NSCachesDirectory inDomains:NSUserDomainMask] lastObject];
NSString* directory = [url path];
NSString* filePath = [directory stringByAppendingPathComponent:FILE_NAME];
NSArray* oldArray = nil;
if ([fileManager fileExistsAtPath:filePath])
{
oldArray = [[NSArray alloc] initWithContentsOfFile:filePath];
[fileManager removeItemAtPath:filePath error:nil];
}
NSMutableArray* mergeArray = [[NSMutableArray alloc] initWithArray:arrayOfPersons];
[mergeArray addObjectsFromArray:oldArray];
if ( [mergeArray writeToFile:filePath atomically:YES]) NSLog(#"Written");
By the way, it cost 1 MB to store an array with only 1 object(an NSDictionary with 2 keys). Is there a cheaper way to store it?
You need to be much more careful with your experiments. The unix file system does lots of stuff with files. In fact, when you "delete" a file, all you do is unlink it from the file system. If that file is open with another file descriptor, anywhere in the OS, it will remain open.
Furthermore, there are lots of optimizations to reuse file nodes. Just because you delete a file, does not mean that space goes back automatically. It could be "reserved" in your app for several reasons, for other files to use. No sense giving it back to the file system until the file system needs it.
settings->general->usage is a very rough measurement of file system utilization. A better measurement would be accessing the attributes of the file and file system directly.
Using your code as a base, consider this:
- (NSString*)workingDirectory {
NSFileManager* fileManager = [NSFileManager defaultManager];
NSURL* url = [[fileManager URLsForDirectory:NSCachesDirectory
inDomains:NSUserDomainMask] lastObject];
return [url path];
}
- (NSString*)filePath {
return [[self workingDirectory] stringByAppendingPathComponent:FILE_NAME];
}
Now, you can see all the attributes of the entire file system with this:
NSDictionary *attributes = [[NSFileManager defaultManager]
attributesOfFileSystemForPath:[self workingDirectory] error:0];
NSLog(#"file system attributes: %#", attributes);
and those for the specific file with this:
NSDictionary *attributes = [[NSFileManager defaultManager]
attributesOfItemAtPath:[self filePath] error:0];
NSLog(#"file attributes: %#", attributes);
Pay attention to NSFileSystemFreeSize and NSFileSize.
Run your app, and dump both of these values. Create your file, and dump them again. Delete the file, and dump them again.
After all that, you may actually see the NSFileSystemFreeSize go UP, even after the delete. Remember, the system itself is creating temporary files, and is probably caching those file system nodes for future use.
You can get more consistent results if you quit all other apps. Then, quit yours (double-click power button, X all running apps). Delete the file before doing this.
Now, start your app, without the file existing.
Dump file system data.
Create the file.
Dump file system data.
Dump file data.
You should see the file taking up about 200-250 bytes, and the file system free size should drop 8192.
Delete the file.
Dump file system data. Is probably at least as big as it was before deleting file.
Quit app (not in XCode -- double-click power, X the app).
Run the app.
Dump file system data. You should see the data back to about what it was when you started earlier.
In conclusion, while it may look like the file system has not released the data, it really has, but maybe the tool you are using to query just does not know the details of the file system.
Note, also, that when an app is running, it will use lots of file system resources for stuff that you are not explicitly doing.
I hope that made sense...
Your code to delete the file looks correct, but you are switching between URLs and Paths when you don't need to. You should also be checking for an error when you try to delete the file so that you can see why it doesn't work. Try this:
NSFileManager *fileManager = [NSFileManager defaultManager];
NSArray *directoryURLs = [fileManager URLsForDirectory:NSCachesDirectory
inDomains:NSUserDomainMask];
NSURL *directoryURL = [directoryURLs objectAtIndex:0];
NSURL *fileURL = [directoryURL URLByAppendingPathComponent:FILE_NAME];
if (!fileURL)
{
NSLog(#"Could not create URL for file.");
return;
}
NSError *err = nil;
if (![fileURL checkResourceIsReachableAndReturnError:&err])
{
NSLog(#"File is not reachable.\n"
"Error: %# %d %#", [err domain], [err code], [[err userInfo] description]);
return;
}
err = nil;
[fileManager removeItemAtURL:fileURL error:&err];
if (err)
{
NSLog(#"Unable to delete existing file.\n"
"Error: %# %d %#", [err domain], [err code], [[err userInfo] description]);
return;
}
May it be, that the length of the ˚FILE_NAME` is greater or equal to 300 chars? This brought me to similar issues with NSFileManager some time ago...