I am using Xcode 7.3.1 and Swift 2.0. I am using the following code sample:
func writeToResourcesDataDir() {
if let path = NSBundle.mainBundle().pathForResource("TestData", ofType: ".json") {
let str = "Test String"
do {
try str.writeToFile(path, atomically: false, encoding: NSUTF8StringEncoding)
print("writeToFile successful")
} catch {
print("writeToFile failed")
}
} else {
print("Path does not exist")
}
}
Running under Xcode in the see the "writeToFile successful" message.But, also using the simulator, I can display the TestData in the Resources directory and the file does not have the string.I also used a terminal window in Mac to look at the files in the Resources directory and the TestData file is empty (0 bytes).I know I am in the correct Resources directory because there is another file in the directory that has correct data that is used for running the other parts of the program.
I have spent several days now looking at other google entries about data from writeToFile not working and I have tried out every fix or things to try I have found.
Can anyone help?
I added code to accept the boolean return from the call to writeToFile and it returns a false. I'm not sure why a false is returned but the catch isn't invoked.I am not sure how to get the error code that goes with this writeToFile in Swift 2.0.
I am also wondering if this is a write permissions problem.Should I be using the Documents directory instead of the Data directory?
Try something like this. This is swift 2.3 and xcode 8.
let filename = "yourjsonfile"
let documentDirectoryURL = try! NSFileManager.defaultManager().URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: true)
let filePath = documentDirectoryURL.URLByAppendingPathComponent(filename)
let fileExist = filePath?.checkResourceIsReachableAndReturnError(nil)
if (fileExist == true) {
print("Found file")
} else {
print("File not found")
}
Related
I am new to programming in general and have started with Swift. I have a feeling what I'm attempting to do is a bit outside of my scope, but I've come so far so here's the ask:
I am adding a tracker to a program for macOS X I've already created. The end user inputs a number and hits "Add to tracker" which then takes that number, the timestamp from the button click and writes that to the appropriate entity in Core Data. Everything works perfectly, my NSTable displays the data and I my batch delete works, but I cannot for the life of me work out the best way to take the results from the NSFetchRequest and print them to a text file.
Here is the code for my fetch request that occurs when the "print" button is hit:
#IBAction func printTracker(_ sender: Any) {
fetchRequest.propertiesToFetch = ["caseDate","caseNumber"]
fetchRequest.returnsDistinctResults = true
fetchRequest.resultType = NSFetchRequestResultType.dictionaryResultType
do {
let results = try context.fetch(fetchRequest)
let resultsDict = results as! [[String:String]]
} catch let err as NSError {
print(err.debugDescription)
}
}
After the "resultsDict" declaration is where I just can't seem to come to a workable solution for getting it to string, then to txt file.
If I add a print command to the console as is, I can see that resultsDict pulls correctly with the following format:
[["caseNumber": "12345", "caseDate": "3/22/21, 5:48:18 PM"]]
Ideally I need it in plaintext more like
"3/22/21, 5:48:18 PM : 12345"
Any advice or help on the conversion would be greatly appreciated.
A simple way if there is not a huge amount of data returned is to create a string from the fetched data and then write that string to disk
First create the string by getting the values from the dictionary and adding them in the right order into a string and joining the strings with a new line character
let output = results.reduce(into: []) { $0.append("\($1["caseDate", default: ""]) : \($1["caseNumber", default: ""])") }
.joined(separator: "\n")
Then we can write them to file, here I use the Document directory as the folder to save the file in
let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
let path = paths[0].appendingPathComponent("results.txt")
do {
try String(output).write(to: path, atomically: true, encoding: .utf8)
} catch {
print("Failed to write to file, error: \(error)")
}
I'm just starting learning Swift and to teach myself I'm making a simple command line app. It will eventually connect to an online data source but initially I want to load data from a file. I've seen various guides on reading the contents of a file in Swift but none of them seem to work for me. Here is my app so far:
import Foundation
// Set the file path
let path = "/Users/username/workspace/Swift/sis/sis/data.json"
do {
// Get the contents
let contents = try String(contentsOfFile: path, encoding: .utf8)
print(contents)
}
catch let error as NSError {
print("Ooops! Something went wrong: \(error)")
}
Running it outputs:
Ooops! Something went wrong: Error Domain=NSCocoaErrorDomain Code=260 "The file “data.json” couldn’t be opened because there is no such file." UserInfo={NSFilePath=/Users/username/workspace/Swift/sis/sis/data.json, NSUnderlyingError=0x100e19a50 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}}
However on the terminal:
$ ls -l /Users/username/workspace/Swift/sis/sis/data.json
-rwxrwxrwx# 1 username staff 165563 16 Jan 17:14 /Users/username/workspace/Swift/sis/sis/data.json
(yeah I relaxed the permissions somewhat just in case that was the problem)
The only slightly anomalous thing I noticed (aside from the inaccurate assertion that the file doesn't exist) was that when I copy and past the path from the XCode output into iTerm2 it puts spaces between each path component:
(pasted as an image as copying it and pasting it back into this form seems to hide the spaces - this is probably irrelevant anyway)
Any help figuring this out would be really appreciated!
I copied your code, downloaded a sample json file to my desktop, and renamed it to example_ 1.json (I included a space inside the file name).
import Foundation
// Set the file path
let path = "/Users/username/Desktop/example_ 1.json"
do {
// Get the contents
let contents = try String(contentsOfFile: path, encoding: .utf8)
print(contents)
}
catch let error as NSError {
print("Ooops! Something went wrong: \(error)")
}
It successfully printed the file. It also worked when I defined contents as a NSString.
let contents = try NSString(contentsOfFile: path,
encoding: String.Encoding.ascii.rawValue)
I am using Swift 4.2.1
you can not read if your command line app is sandboxed. what you can do is to add this file in your project and set path of file by looking the full path of file in identity inspector.
let path = "/Users/snx/EmailReplacer/EmailReplacer/shared_domains_staging.json"
do {
let data = try Data(contentsOf: URL(fileURLWithPath: path), options: .mappedIfSafe)
let jsonResult = try JSONSerialization.jsonObject(with: data, options: .mutableLeaves)
if let jsonResult = jsonResult as? Dictionary<String, AnyObject> {
print(jsonResult)
}
} catch {
print(error)
}
I'm using the swift ubuntu docker: https://github.com/IBM-Swift/swift-ubuntu-docker
and try to copy a file from pathA to pathB. During the execution I get the fatal error:
fatal error: copyItem(atPath:toPath:) is not yet implemented: file Foundation/NSFileManager.swift, line 376
Illegal instruction
The command:
# swift --version
responses
Swift version 3.1.1 (swift-3.1.1-RELEASE)
Target: x86_64-unknown-linux-gnu
Online I found the information that it should be implemented:
https://bugs.swift.org/browse/SR-2639
Can someone help out? Thanks!
copyItem(atPath:toPath:) is not implemented on the Swift 3.1 branch
of the Foundation framework for Linux:
open func copyItem(atPath srcPath: String, toPath dstPath: String) throws {
NSUnimplemented()
}
What you can for example do is
let fm = FileManager.default
if let contents = fm.contents(atPath: srcPath) {
if !fm.createFile(atPath: destPath, contents: contents, attributes: nil) {
print("cannot write destination file")
}
} else {
print("cannot read source file")
}
which is a simplified version of how copyItem(atPath:toPath:)
is implemented on the master branch.
If the file is very large then you may want to copy in chunks
instead of reading the entire file into memory, for example like this:
guard let srcFile = FileHandle(forReadingAtPath: srcPath) else {
fatalError("cannot open source file")
}
guard let destFile = FileHandle(forWritingAtPath: destPath) else {
fatalError("cannot open destination file")
}
while case let data = srcFile.readData(ofLength: 1024 * 1024), data.count > 0 {
destFile.write(data)
}
srcFile.closeFile()
destFile.closeFile()
Thanks that works fine. I found in the meanwhile another solution which also works ;-)
let data = try Data.init(contentsOf: URL.init(fileURLWithPath: path))
guard FileManager.default.createFile(atPath: url.path, contents: data, attributes: nil) else {
print("Can not read/create the file")
return false
}
I have a file that exists within the AppGroup Shared Container and I was wondering if it was possible to copy the file from the Shared Container into the application bundle.
I am getting the file path as follows :
let filePath = NSFileManager.defaultManager().containerURLForSecurityApplicationGroupIdentifier("group.com.sharedBasemap")!.URLByAppendingPathComponent("localLayer.tpk")!.path
The reason I am trying to do this is it seems that the ArcGIS SDK will not recognize the TPK file from within the App Group so I am wondering if it will recognize it if I copy it into the app bundle.
EDIT: Based on Leo's comment it appears that you can not copy to the bundle, so I am trying to copy to the App Support folder.Here is my code now, I see the "file exists" message but then it is displaying the Oops message indicating it can not move the file :
let filePath = NSFileManager.defaultManager().containerURLForSecurityApplicationGroupIdentifier("group.com.sharedBasemap")!.URLByAppendingPathComponent("localLayer.tpk")!.path!
let appSupportFolder = String(NSFileManager.defaultManager().URLsForDirectory(.ApplicationSupportDirectory, inDomains: .UserDomainMask)[0]) + "localLayer.tpk"
let fileManager = NSFileManager.defaultManager()
if NSFileManager.defaultManager().fileExistsAtPath(filePath){
print("File exists at \(filePath)")
do {
try fileManager.copyItemAtPath(filePath, toPath: appSupportFolder)
}
catch let error as NSError {
print("Ooops! Something went wrong: \(error)")
}
} else {
print("File does not exist")
}
EDIT 2: I have modified the code again to just move the TPK file into the documents directory.I believe that piece is working but I receive an error message when trying to load the TPK file into ArcGIS.At this point in time, I am thinking that the issue is related to the ArcGIS SDK and that it does not support loading a TPK file from anywhere except the application bundle.
let destPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first!
let fullDestPath = NSURL(fileURLWithPath: destPath).URLByAppendingPathComponent("localLayer.tpk")
let fullDestPathString = fullDestPath!.path!
im pretty sure the appSupportFolder doesn't exist by default -- nobody creates it unless needed -- try to verify that first and create it if needed
pseudocode if(!fileExists(supportFolder)) { createDirectory(supportFolder) }
As an exercise, I'm trying to write a logging class that logs strings to a text file. I've got my application to write and read from the file. However, if I try to log multiple times it seems to only pick up the most recent log.
Attempt
writing
private let file = "logfile.txt"
func write(text: String) {
let path = getDocumentsDirectory()
do {
try text.writeToFile(path, atomically: false, encoding: NSUTF8StringEncoding)
}
catch let error {
print("error: \n \(error)")
}
}
reading
func read() {
let path = getDocumentsDirectory()
do {
let text2 = try String(contentsOfFile: path, encoding: NSUTF8StringEncoding)
print("From Log: \n \(text2)")
}
catch let error {
print("error: \n \(error)")
}
}
func getDocumentsDirectory() -> String {
guard let dir : NSString = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first else {
return ""
}
let documentsDirectory : String = dir.stringByAppendingPathComponent(file)
return documentsDirectory
}
Result
When I try to read my file I only get the last line saved.
Question
If my goal is to endlessly append new logs to a file, and to read the log file in bulk. What changes to my code do I need to make?
more details:
I'm writing to the file on application load:
Logger.shared.write("instance one writes")
Logger.shared.write("instance one writes again")
Logger.shared.write("instance one writes yet again")
and then attempting to read:
Logger.shared.read()
output:
From Log:
instance one writes yet again
The writeToFile(_:atomically:encoding:) method provided by Foundation replaces the contents of the given file. There are several ways of appending to files:
Plain ol’ fopen (with mode "a") and fwrite.
NSOutputStream, such as NSOutputStream(toFileAtPath: mypath, append: true), using stream.write(bytes, len) to write data.
Perhaps the easiest, NSFileHandle, such as NSFileHandle(forWritingAtPath: mypath), using seekToEndOfFile() and writeData().