So in my app I have a bunch of data that I'd like to write to a log file, and then display it within a UITextView when I click a button. I know how to toggle the UITextView, but I have no idea how to create and update a log file (in the local filesystem). Thanks for any help.
The basic idea is that you create the file, and append to it every time you log a new line. You can do it quite easily like this:
Writing to the file:
NSString *content = #"This is my log";
//Get the file path
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *fileName = [documentsDirectory stringByAppendingPathComponent:#"myFileName.txt"];
//create file if it doesn't exist
if(![[NSFileManager defaultManager] fileExistsAtPath:fileName])
[[NSFileManager defaultManager] createFileAtPath:fileName contents:nil attributes:nil];
//append text to file (you'll probably want to add a newline every write)
NSFileHandle *file = [NSFileHandle fileHandleForUpdatingAtPath:fileName];
[file seekToEndOfFile];
[file writeData:[content dataUsingEncoding:NSUTF8StringEncoding]];
[file closeFile];
Reading:
//get file path
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *fileName = [documentsDirectory stringByAppendingPathComponent:#"myFileName.txt"];
//read the whole file as a single string
NSString *content = [NSString stringWithContentsOfFile:fileName encoding:NSUTF8StringEncoding error:nil];
I thought was a class out there to do this automatically as after no luck created my own.
NSLogger is a lightweight class for iOS versions 3.0 and above. It allows developers to easily log different 'events' over time which are locally stored as a .txt file.
https://github.com/northernspark/NSLogger
Related
I am trying to save the string in .txt file and wants to see that .txt file in Files app. It is possible to save and read the file in documents directory but I am struggling to save and see in Files app.
Your help will be appreciated.
You can create the file with:
NSString* filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString* fileName = #"file.txt";
NSString* fileAtPath = [filePath stringByAppendingPathComponent:fileName];
if (![[NSFileManager defaultManager] fileExistsAtPath:fileAtPath]) {
[[NSFileManager defaultManager] createFileAtPath:fileAtPath contents:nil attributes:nil];
}
And read it with:
NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *fileName = #"file.txt";
NSString *pathDocuments = [filePath stringByAppendingPathComponent:fileName];
After having the file path then it is up to you to parse it.
I'm writing an application for the Apple watch. I'm using the following method (from this SE answer) to write to a log file:
- (void) writeLogWith: (NSString *) content {
//Get the file path
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *fileName = [documentsDirectory stringByAppendingPathComponent:#"whathappened.md"];
//create file if it doesn't exist
if(![[NSFileManager defaultManager] fileExistsAtPath:fileName])
[[NSFileManager defaultManager] createFileAtPath:fileName contents:nil attributes:nil];
//append text to file (you'll probably want to add a newline every write)
NSFileHandle *file = [NSFileHandle fileHandleForUpdatingAtPath:fileName];
[file seekToEndOfFile];
[file writeData:[content dataUsingEncoding:NSUTF8StringEncoding]];
[file closeFile];
return;
}
I'm running it by plugging in my phone and running it directly on my watch. The function is definitely executing (I've stepped thought with the debugger) and it also knows that the file exists and doesn't repeatedly try and create it.
Xcode tells me that the file information is:
Printing description of documentsDirectory:
/var/mobile/Containers/Data/PluginKitPlugin/8503AD6C-6EC9-4522-A867-27109B01B615/Documents
Printing description of documentsDirectory:
(NSString *) documentsDirectory = 0x16d66890
Printing description of fileName:
(NSString *) fileName = 0x16d66950
Printing description of fileName:
/var/mobile/Containers/Data/PluginKitPlugin/8503AD6C-6EC9-4522-A867-27109B01B615/Documents/whathappened.md
I'd like to know if it's writing things correctly, but when I look at the container (following these SE answers), the documents directory is empty.
My question is: where did my file go? And how can I find it?
I think what might be giving you problems is the NSFileHandle object. I have written thousands upon thousands of files to the documents folder and I have never used NSFileHandle to do this. Simply use the built in method on NSString to write your string to the file path.
Try this:
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *filePath = [[documentsDirectory stringByAppendingPathComponent:#"whathappened"] stringByAppendingPathExtension:#"md"];
if (![[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
[[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil];
}
NSString *string = #"The String You Want To Write.";
NSError *error;
[string writeToFile:filePath atomically:false encoding:NSUTF8StringEncoding error:&error];
if (error) {
NSLog(#"There was an error writing file\n%#", error.localizedDescription);
}
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
NSLog(#"File exists :)");
}
else {
NSLog(#"File does not exist :(");
}
From other research, the answer appears to be:
If you are storing a file on the Apple Watch, it is stored in it's own container, which isn't visible via xcode.
It indeed, appears to be related to this bug report: https://openradar.appspot.com/radar?id=5021353337946112, found via this SE: How to export shared container of an iOS App with Xcode6.2?
When there is no internet connection on device, i am storing the json in to a text file. But the problem is, if i do again it is getting replaced. Here is what i am doing for store into a text file. How to store multiple json object in a text file.When i get connection i need to post json to server.
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex:0];
NSString *filePath = [docDir stringByAppendingPathComponent:#"File.json"];
[jsonString writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:&error];
Please advice.
That's not so straight forward as concatenating multiple JSON files does not result in a valid JSON file. To do this properly requires you to read and parse the existing JSON file, which will give you an NSArray or NSDictionary top-level object, then append the data from the new JSON file and write the whole thing out.
That is inefficient as you are processing old data.
Therefore I would suggest you write new data to a new file, using the current date/time for the filename, and when it's time to upload, read each of the files and upload them individually, one-at-a-time. Then delete each file as it's uploaded.
Use below method to append text to file
-(void) writeToLogFile:(NSString*)content{
content = [NSString stringWithFormat:#"%#\n",content];
//get the documents directory:
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDir = [paths objectAtIndex:0];
NSString *filePath = [docDir stringByAppendingPathComponent:#"File.json"];
NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:fileName];
if (fileHandle){
[fileHandle seekToEndOfFile];
[fileHandle writeData:[content dataUsingEncoding:NSUTF8StringEncoding]];
[fileHandle closeFile];
}
else{
[content writeToFile:fileName
atomically:NO
encoding:NSStringEncodingConversionAllowLossy
error:nil];
}
}
I have a .txt file with a small password in it. I would like to change that file's text. How can I do that? I can get the file's text using :
NSString *passWord = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"password" ofType:#"txt"] encoding:NSUTF8StringEncoding error:NULL];
But I can't seem to find a way to replace the contents of the file with a string.
The way to do this is to remove old file and create new one.
Removing existing file
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingPathComponent:#"myFile.txt"];
NSFileManager *fileManager = [NSFileManager defaultManager];
if([fileManager fileExistsAtPath:filePath])
{
[fileManager removeItemAtPath:filePath error:&error];
}
To crate new file with your new password write password data while creating file as:
[createFileAtPath:path contents:[NSData data] attributes:nil]
I created a text file in ios and it is stored in Data files in following location.Sandbox => Documents => mylogfile.txt.
This file is updates only when I connected my Device with Mac and Xcode only.If I eject the device, and connect again to see the updated text file. It is not updated. It will be same as old file. The log file does not updated when disconnected from PC.
How to update text file on all time.
My Code:
-(void)logme:(NSString *)mymessage
{
NSString *content = mymessage;
//Get the file path
NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *fileName = [documentsDirectory stringByAppendingPathComponent:#"locationlog.txt"];
//create file if it doesn't exist
if(![[NSFileManager defaultManager] fileExistsAtPath:fileName])
[[NSFileManager defaultManager] createFileAtPath:fileName contents:nil attributes:nil];
//append text to file (you'll probably want to add a newline every write)
NSFileHandle *file = [NSFileHandle fileHandleForUpdatingAtPath:fileName];
[file seekToEndOfFile];
[file writeData:[content dataUsingEncoding:NSUTF8StringEncoding]];
[file closeFile];
}
and called this log file like,
[self logme:myHTML];