Saved image does not appear in file directory - objective-c

I'm using the following code below save an image locally. It works without any errors, and I can preview the incoming image. The only problem is that the image never seems to actually be saved or appear in the Images directory. I use iExplorer to double check, and I have refreshed the folder and the image is still not there. Your thoughts are appreciated.
// I can preview this UIImage and it appears as expected
UIImage *image = [UIImage imageWithData:responseObject]; //responseImage is an image from online
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *docs = [paths objectAtIndex:0];
NSString* path = [docs stringByAppendingFormat:#"/Images/image1.jpg"];
NSData* imageData = [NSData dataWithData:UIImageJPEGRepresentation(image, .8)];
NSError *writeError = nil;
if(![imageData writeToFile:path options:NSDataWritingAtomic error:&writeError]) {
//This never fires, so you would think the image would have saved, but that does not appear to be the case!
NSLog(#"%#: Error saving image: %#", [self class], [writeError localizedDescription]);
}
I did also check to see if the file exists programmatically and apparently it does exist. However, when I try to reference it within a UIWebview, it doesn't load anything for that image.

Remember that NSFileManagers use NSString paths to read/write files, however UIWebViews use NSURLs. In order for you to load the file into a UIWebView, you'll need to convert your NSString path into an NSURL file URL.
So instead of something that looks like:
/Documents/Path/To/File.png
It needs to be
file:///Documents/Path/To/File.png
I believe the correct way to do this is to use the [NSURL fileURLWithPath:] method.
So it would look something like this:
NSFileManager* fileManager = [NSFileManager defaultManager];
NSString* path; //However you got your path here
if([fileManager fileExistsAtPath:path])
{
NSURL* fileURL = [NSURL fileURLWithPath:path];
NSURLRequest* request = [NSURLRequest requestWithURL: fileURL];
[_myWebView loadRequest:request];
}

This is too long to post as a comment, so I'm posting it as an answer.
I'm not sure about your if statement there. It does return a BOOL NO if the file operation fails, but I'm not exactly sure what "the operation fails" means. Just because the file is not written out does not necessarily mean that the operation failed. So it's better to check the NSError itself.
Instead of checking ![writeToFile], run the line without the if statement, and then check if(writeError != nil). If the if statement is true, then something went wrong, and if so, you can check the localized description of the error.
So to recap,
NSError* writeError = nil;
[imageData writeToFile:path options:NSDataWritingAtomic error:&writeError];
if(writeError != nil)
{
//Something went wrong
NSLog("File write error: %#", writeError.localizedDescription);
}

Related

Objective C can't read text file when running on iPhone

I've made an app that is relying on reading and writing a plist-file. This works well when I'm running the app in the iPhone simulator, but doesn't work at all when I'm testing it on my iPhone. I've also made a pre made text file in .txt format with demo data. The app works when I'm running this file.
All the reading and writing is done in a class that looks like this:
-(void)saveArray:(NSMutableArray *)inputArray
{
albumArray = inputArray;
NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentFolder = [path objectAtIndex:0];
NSString *filePath = [documentFolder stringByAppendingFormat:#"albums.plist"];
[albumArray writeToFile:filePath atomically:YES];
}
Update: Changed the string from "stringByAppendingFormat" to "stringByAppendingPathComponent" and it seems to work now. Thanks a lot! You guys made my day made.
Are you sure, that the folders already exist?
Here is a function i'm using to get the path to my file:
- (NSString*) pathToSavedAlbums
{
NSURL *applicationSupportURL = [self applicationDataDirectory];
if (! [[NSFileManager defaultManager] fileExistsAtPath:[applicationSupportURL path]])
{
NSError *error = nil;
[[NSFileManager defaultManager] createDirectoryAtPath:[applicationSupportURL path]
withIntermediateDirectories:YES
attributes:nil
error:&error];
if (error)
{
NSLog(#"error creating app support dir: %#", error);
}
}
NSString *path = [[applicationSupportURL path] stringByAppendingPathComponent:#"albums.plist"];
return path;
}
Check the spelling of the plist name as well as the case, device is case sensitive for docs but simulator isn't. Also try deleting the app from the device and reinstalling it ?
writeToFile:atomically: returns a bool, so check that to see if it fails to even write to the path. Check the file path string and ensure this is where you want it to go.

NSString writeToFile, NSSavePanel and write permissions

I've only been leaning Cocoa/Objective C for a few days so apologies that this is probably simple/obvious but it's got me stumped.
I've written this handler for saving 3 floats to a text file. However when I'm running it the files are not being saved. Could anyone suggest if there's an error in my code or if you think there's something else (like file write permissions) preventing the file from being written.
Research has lead me to look into Sandboxing, but that gets confusing very quickly and I'm hoping just running the app from xcode in debug would let me write to my user directory.
Heres the code:
- (IBAction)saveResultsAction:(id)sender {
//Sets up the data to save
NSString *saveLens = [NSString stringWithFormat:#"Screen width is %.02f \n Screen Height is %.02f \n Lens is %.02f:1",
self.myLens.screenWidth,
self.myLens.screenHeight,
self.myLens.lensRatio];
NSSavePanel *save = [NSSavePanel savePanel];
long int result = [save runModal];
if (result == NSOKButton) {
NSURL *selectedFile = [save URL];
NSLog(#"Save URL is %#", selectedFile);
NSString *fileName = [[NSString alloc] initWithFormat:#"%#.txt", selectedFile];
NSLog(#"Appended URL is %#", fileName);
[saveLens writeToFile:fileName
atomically:YES
encoding:NSUTF8StringEncoding
error:nil];
}
}
a NSURL object is no POSIX path..
its a URL and getting its description doesnt make it a path
NSString *fileName = [selectedFile.path stringByAppendingPathExtension:#"txt"];
BUT as said, you shouldnt have to append the .txt at all. just use what the panel returns. Else, there would be sandboxd errors because you dont have access rights to the modified filename :)
NSString *fileName = selectedFile.path;
The problem is that you don't need to append the file extension to the URL.The extension is already there.You could directly do this:
if (result == NSOKButton)
{
[saveLens writeToURL: [save URL]
atomically:YES
encoding:NSUTF8StringEncoding
error:nil];
}
I see you've already accepted an answer, but it may also be helpful to know how to debug this type of issue using NSError pointers.
Cocoa uses NSError with method calls which generate error conditions, which richly encapsulate errors. (Objective-C also has exceptions, but they're reserved for cases of programmer error, like an array index out of bounds, or a nil parameter that should never be.)
When you have a method which accepts an error pointer, usually it also return a BOOL indicating overall success or failure. Here's how to get more information:
NSError *error = nil;
if (![saveLens writeToFile:fileName
atomically:YES
encoding:NSUTF8StringEncoding
error:&error]) {
NSLog(#"error: %#", error);
}
Or even:
NSError *error = nil;
if (![saveLens writeToFile:fileName
atomically:YES
encoding:NSUTF8StringEncoding
error:&error]) {
[NSApp presentError:error];
}

Problem getting files from folder, error recognizing folder. (Objective c)

I have the user select a folder from an NSOpenPanel. This returns a filepath like: file://localhost/Folder. Here is my code where it all goes wrong:
NSURL *filePath = [openDlg URL]; //OpenDlg is my NSOpenPanel
NSString *s = [filePath absoluteString];
NSLog(#"%#",s);
NSError *error;
NSArray *b = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:s error:&error];
if (error) {
NSLog(#"%#",error);
}
NSLog(#"%lu",b.count);
Here, no matter what folder I select, this error message is sent: The folder “Folder” doesn’t exist." UserInfo=0x10518b320 {NSFilePath=file://localhost/Folder, NSUserStringVariant=(
Folder
), NSUnderlyingError=0x10515d5e0 "The operation couldn’t be completed. (OSStatus error -43.)"}
What is going on?!? If this isn't the best way to do it how can I access all the files inside of a folder?
Try using this method instead:
- (NSArray *)contentsOfDirectoryAtURL:(NSURL *)url includingPropertiesForKeys:(NSArray *)keys options:(NSDirectoryEnumerationOptions)mask error:(NSError **)error
You can just pass in the NSURL without having to convert it into a NSString. To give you an example of how you would use it, see below:
[[NSFileManager defaultManager] contentsOfDirectoryAtURL:filePathURL
includingPropertiesForKeys:[NSArray arrayWithObjects:NSURLNameKey, nil]
options:NSDirectoryEnumerationSkipsHiddenFiles
error:&error];
I can't see how you setup your NSOpenPanel so I will also include an example of how to set that up below:
NSOpenPanel *openPanel = [NSOpenPanel openPanel];
[openPanel beginSheetModalForWindow:self.window completionHandler:^(NSInteger result){
if (result == NSFileHandlingPanelOKButton) {
NSArray* urls = [openPanel URLs];
NSURL *url = [urls objectAtIndex:0];
if (url != nil) {
// If you want to convert the path to a NSString
self.filePathString = [url path];
// If you want to keep the path as a NSURL
self.filePathURL = url;
}
}
}];
The above method will get the path to the file or folder after the user has pressed the OK button. Give that a try and see if it works. To further elaborate on why I suggested you use NSURL, here is the explanation that the Apple Documentation gives:
The preferred way to specify the location of a file or directory is to use the NSURL class. Although the NSString class has many methods related to path creation, URLs offer a more robust way to locate files and directories. For applications that also work with network resources, URLs also mean that you can use one type of object to manage items located on a local file system or on a network server.

Write to file not working

I'm trying to combine images in my app into one file and write it to disk.
NSMutableArray *array = [NSMutableArray arrayWithObjects:
[NSData dataWithContentsOfFile:#"0.png"],
[NSData dataWithContentsOfFile:#"1.png"],
[NSData dataWithContentsOfFile:#"2.png"],
nil];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSError *error = nil;
NSString *path=#"/Users/myusername/Desktop/_stuff.dat";
[data writeToFile:path options:NSDataWritingAtomic error:&error];
or
NSArray *array = [NSArray arrayWithObjects:
[NSImage imageNamed:#"0"],
[NSImage imageNamed:#"1"],
[NSImage imageNamed:#"2"],
nil];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSError *error = nil;
NSString *path=#"/Users/myusername/Desktop/_stuff.dat";
[data writeToFile:path options:NSDataWritingAtomic error:&error];
But both produce a file that is 4KB (empty). If I NSLog the error it is (null). Am I making the data the wrong way?
Edit: If I open the resulting file with a text editor, it looks like this:
I wrote a quick example:
Missing: memory management / error handling / proper file handling
// Archive
NSMutableArray *array = [[NSMutableArray alloc] init];
NSString * input = #"/Users/Anne/Desktop/1.png";
[array addObject:[NSData dataWithContentsOfFile:input]];
[array addObject:[NSData dataWithContentsOfFile:input]];
[array addObject:[NSData dataWithContentsOfFile:input]];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSString *path = #"/Users/Anne/Desktop/archive.dat";
[data writeToFile:path options:NSDataWritingAtomic error:nil];
// Unarchive
NSMutableArray *archive = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
NSData * firstObject = [archive objectAtIndex:0];
NSString * output = #"/Users/Anne/Desktop/2.png";
NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:output];
[firstObject writeToURL:fileURL atomically:YES];
You can also add NSImages to the NSMutableArray:
NSString * input = #"/Users/Anne/Desktop/1.png";
NSImage *image = [[NSImage alloc] initWithContentsOfFile: input];
[array addObject:image];
But that will significantly increase the file size.
Response to the following comment:
So if I only need to access an image at runtime (in the archive), is there a way to access that image at an index without unarchiving the whole thing? Seems like unnecessary overhead to me.
I assume you're still struggling with this problem?
Hiding (or encrypting) app resources?
Like i mentioned earlier, combining all files into one big file does the trick.
Just make sure you remember the file-length of each file and file-order.
Then you can extract any specific file you like without reading the whole file.
This might be a more sufficient way if you only need to extract one file at the time.
Quick 'dirty' sample:
// Two sample files
NSData *fileOne = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/1.png"];
NSData *fileTwo = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/2.png"];
// Get file length
int fileOneLength = [fileOne length];
int fileTwoLength = [fileTwo length];
// Combine files into one container
NSMutableData * container = [[NSMutableData alloc] init];
[container appendData:fileOne];
[container appendData:fileTwo];
// Write container to disk
[container writeToFile:#"/Users/Anne/Desktop/container.data" atomically:YES];
// Read data and extract sample files again
NSData *containerFile = [NSData dataWithContentsOfFile:#"/Users/Anne/Desktop/container.data"];
NSData *containerFileOne =[containerFile subdataWithRange:NSMakeRange(0, fileOneLength)];
NSData *containerFileTwo =[containerFile subdataWithRange:NSMakeRange(fileOneLength, fileTwoLength)];
// Write extracted files to disk (will be exactly the same)
[containerFileOne writeToFile:#"/Users/Anne/Desktop/1_extracted.png" atomically:YES];
[containerFileTwo writeToFile:#"/Users/Anne/Desktop/2_extracted.png" atomically:YES];
// Only extract one file from the container
NSString * containerPath = #"/Users/Anne/Desktop/container.data";
NSData * oneFileOnly = [[NSFileHandle fileHandleForReadingAtPath:containerPath] readDataOfLength:fileOneLength];
// Write result to disk
[oneFileOnly writeToFile:#"/Users/Anne/Desktop/1_one_file.png" atomically:YES];
Tip:
You can also save the 'index' inside the container file.
For example: The first 500 bytes contain the required information.
When you need a specific file: Read the index, get the file position and extract it.
You are archiving a NSMutable array of NSImage. This two classes conform to the NSCoding protocol required by NSKeyedArchiver, so I don't see where would be your problem.
So, here are many ideas to test.
First, are you sure that the data you think you have are valid? In your first code snippet, you write [NSData dataWithContentsOfFile:#"0.png"]. This method expects an absolute file path.
Assuming the problem is not in your code, just in your question, let's continue:
Do you have something different than nil in the variable data after your archiving? Ie, after the assignement to data, can you add this code. If the assertion fail, you will get an exception at runtime:
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
NSAssert(nil != data, #"My object data is nil after archiving");
If the problem was not here, what is the return of the line [data writeToFile:path options:NSDataWritingAtomic error:&error];
(Not the variable error, but the return value of the call to the method - writeToFile: options: error:)
What happens if you simplify your code and just do this:
result = [NSKeyedArchiver archiveRootObject:data
toFile:archivePath];
If everything was ok, have you tried to unarchive your file with NSKeyedUnarchiver?
The problem is that [NSData dataWithContentsOfFile:#"0.png"] looks for the file "0.png" in the current directory, but what the application thinks of as the current directory is probably not the place you're expecting. For graphical apps, you should always either use an absolute path or a path relative to some place that you can get the absolute path of (e.g. your app bundle, the application support directory, some user-selected location).
For command-line tools, using the current directory is more common. But I doubt that's the case here.
Another thing I noticed on Mavericks and up is that the folders in the path must be in existence. Meaning you must create the folder structure prior to saving into that folder. If you try to write to a folder on the desktop or elsewhere, even with sandboxing off, it will fail if the folder does not exist. I know this has been answered already, but I found that my issue continued regardless, but once I make sure that the folder structure was in place, I could do my writing to that folder.
On a side note: I'm sure that you could do this from NSFileManager, and I'll be doing that myself once I finalize my app structure, but hope this helps someone else lost in the sauce.

Saving a string into file in Objective-C (iPhone)

I seem to have stumbled over a problem regarding saving an xml file from a string (this is done on the iPhone)
The file itself exists and included in the project (hence within the workspace), and all indications I get from the code snippet which follows passes without any errors on the emulator and fail on the iPhone (error 513), but in either case the file is not saved!
{
Hits = config->Hits;
NSString* filenameStr = [m_FileName stringByAppendingFormat: #".xml" ];
NSString* pData = [self getDataString]; // write xml format - checked out ok
NSError *error;
/* option 2 - does not work as well
NSBundle *mainBundle = [NSBundle mainBundle];
NSURL *xmlURL = [NSURL fileURLWithPath:[mainBundle pathForResource: m_FileName ofType: #"xml"]];
if(![pData writeToURL: xmlURL atomically: true encoding:NSUTF8StringEncoding error:&error])
{
NSLog(#"Houston - we have a problem %s#\n",[error localizedFailureReason]);
return false;
}
*/
if(![pData writeToFile: filenameStr atomically: FALSE encoding:NSUTF8StringEncoding error:&error])
{
NSLog(#"Houston - we have a problem %s#\n",[error localizedFailureReason]);
return false;
}
return true;
}
Any help would be appreciated,
-A
You should not write to files included in the application package. On a real iPhone, you may be prevented from doing this because these files are digitally signed.
Even if you can modify a packaged file, it is not a good place to store data. Re-installing the application from an App Store upgrade or an Xcode build will overwrite the file with the original.
Instead, store your XML into the Documents directory. You can get the path like this:
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask, YES);
NSString* documentsDirectory = [paths objectAtIndex:0];
NSString* leafname = [m_FileName stringByAppendingFormat: #".xml" ];
NSString* filenameStr = [documentsDirectory
stringByAppendingPathComponent:leafname];
If your file needs some initial state that you don't want to generate in your code, have your app check that it is present in the documents directory the first time it is needed and, if it is missing, copy it from the template in the package.
An alternative to storing structured data is to use user defaults. For example:
[[NSUserDefaults standardUserDefaults] setObject:foo forKey:FOO_KEY];