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qFile doesn't open on iOS

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  • SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote on last edited by
    #2

    Hi,

    You should use QStandardPaths to get access to a writable folder. You are currently using a relative path which means that you are trying to write inside the application bundle which is forbidden.

    Note that you should use QStandardPaths on all platform to avoid trying to write to ready-only folders.

    Interested in AI ? www.idiap.ch
    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

    1 Reply Last reply
    2
    • K kgregory

      I'm using QFile to read and write files on my mobile app as below.

      QFile myFile("myfile.txt");
      if (myFile.open(QIODevice::ReadOnly)) {
          //read stuff
          myFile.close();
      } else {
          qDebug() << "File open failed.";
      }
      

      This works ok in Android, but in iOS, it doesn't work. Is there something I need to put in my Info.plist file to enable this or is there some other reason why this wouldn't work on iOS?

      ekkescornerE Offline
      ekkescornerE Offline
      ekkescorner
      Qt Champions 2016
      wrote on last edited by
      #3

      @kgregory I'm storing my app datafiles here:

          // Android: HomeLocation works, iOS: not writable
          // Android: AppDataLocation works out of the box, iOS you must create the DIR first !!
          myPath = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).value(0);
      

      attention: on iOS you must create the directory where on Android it exists already
      I'm always creating a /data folder at AppDataLocation to store my files in

      ekke ... Qt Champion 2016 | 2024 ... mobile business apps
      5.15 --> 6.9 https://t1p.de/ekkeChecklist
      QMake --> CMake https://t1p.de/ekkeCMakeMobileApps

      K J.HilkJ 2 Replies Last reply
      4
      • ekkescornerE ekkescorner

        @kgregory I'm storing my app datafiles here:

            // Android: HomeLocation works, iOS: not writable
            // Android: AppDataLocation works out of the box, iOS you must create the DIR first !!
            myPath = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).value(0);
        

        attention: on iOS you must create the directory where on Android it exists already
        I'm always creating a /data folder at AppDataLocation to store my files in

        K Offline
        K Offline
        kgregory
        wrote on last edited by
        #4

        @ekkescorner

        So will myPath (in your example) be a directory specific to my application or is it a general folder that all of the applications use?

        1 Reply Last reply
        0
        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #5

          AppDataLocation is only for your application.

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          1 Reply Last reply
          1
          • K Offline
            K Offline
            kgregory
            wrote on last edited by
            #6

            Thanks! Here's the code I have now. It appears to be working, although I don't have my bluetooth device handy right now which prevents me from fully testing it.

            QString m_dataLocation = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).value(0);
                if (QDir(m_dataLocation).exists()) {
                    qDebug() << "App data directory exists. " << m_dataLocation;
                } else {
                    if (QDir("").mkpath(m_dataLocation)) {
                        qDebug() << "Created app data directory. " << m_dataLocation;
                    } else {
                        qDebug() << "Failed to create app data directory. " << m_dataLocation;
                    }
                }
            
            QFile myFile(m_dataLocation + "/myfile.txt");
            if (myFile.open(QIODevice::ReadOnly)) {
                //read stuff
                myFile.close();
            } else {
                qDebug() << "File open failed.";
            }
            
            ekkescornerE 1 Reply Last reply
            0
            • K kgregory

              Thanks! Here's the code I have now. It appears to be working, although I don't have my bluetooth device handy right now which prevents me from fully testing it.

              QString m_dataLocation = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).value(0);
                  if (QDir(m_dataLocation).exists()) {
                      qDebug() << "App data directory exists. " << m_dataLocation;
                  } else {
                      if (QDir("").mkpath(m_dataLocation)) {
                          qDebug() << "Created app data directory. " << m_dataLocation;
                      } else {
                          qDebug() << "Failed to create app data directory. " << m_dataLocation;
                      }
                  }
              
              QFile myFile(m_dataLocation + "/myfile.txt");
              if (myFile.open(QIODevice::ReadOnly)) {
                  //read stuff
                  myFile.close();
              } else {
                  qDebug() << "File open failed.";
              }
              
              ekkescornerE Offline
              ekkescornerE Offline
              ekkescorner
              Qt Champions 2016
              wrote on last edited by
              #7

              @kgregory great to hear that it works for you.

              ekke ... Qt Champion 2016 | 2024 ... mobile business apps
              5.15 --> 6.9 https://t1p.de/ekkeChecklist
              QMake --> CMake https://t1p.de/ekkeCMakeMobileApps

              1 Reply Last reply
              0
              • ekkescornerE ekkescorner

                @kgregory I'm storing my app datafiles here:

                    // Android: HomeLocation works, iOS: not writable
                    // Android: AppDataLocation works out of the box, iOS you must create the DIR first !!
                    myPath = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).value(0);
                

                attention: on iOS you must create the directory where on Android it exists already
                I'm always creating a /data folder at AppDataLocation to store my files in

                J.HilkJ Offline
                J.HilkJ Offline
                J.Hilk
                Moderators
                wrote on last edited by
                #8

                @ekkescorner said in qFile doesn't open on iOS:

                @kgregory I'm storing my app datafiles here:

                    // Android: HomeLocation works, iOS: not writable
                    // Android: AppDataLocation works out of the box, iOS you must create the DIR first !!
                    myPath = QStandardPaths::standardLocations(QStandardPaths::AppDataLocation).value(0);
                

                attention: on iOS you must create the directory where on Android it exists already
                I'm always creating a /data folder at AppDataLocation to store my files in

                This, should really be in the documentation, right here
                I spend way to much time on this, thanks @ekkescorner !


                Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                Q: What's that?
                A: It's blue light.
                Q: What does it do?
                A: It turns blue.

                1 Reply Last reply
                1
                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #9

                  @J-Hilk Patches for the documentation are also welcomed ;-)

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                  J.HilkJ 1 Reply Last reply
                  0
                  • SGaistS SGaist

                    @J-Hilk Patches for the documentation are also welcomed ;-)

                    J.HilkJ Offline
                    J.HilkJ Offline
                    J.Hilk
                    Moderators
                    wrote on last edited by
                    #10

                    @SGaist
                    :D
                    sure, but honestly I wouldn't know where to start, is there a dokumentaion/guide for it?
                    It's not that the docs are a wiki and just anyone con click on edit in the upper right corner.


                    Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                    Q: What's that?
                    A: It's blue light.
                    Q: What does it do?
                    A: It turns blue.

                    aha_1980A 1 Reply Last reply
                    0
                    • J.HilkJ J.Hilk

                      @SGaist
                      :D
                      sure, but honestly I wouldn't know where to start, is there a dokumentaion/guide for it?
                      It's not that the docs are a wiki and just anyone con click on edit in the upper right corner.

                      aha_1980A Offline
                      aha_1980A Offline
                      aha_1980
                      Lifetime Qt Champion
                      wrote on last edited by
                      #11

                      @J.Hilk

                      You might want to look at https://wiki.qt.io/Gerrit_Introduction

                      Qt has to stay free or it will die.

                      1 Reply Last reply
                      1
                      • SGaistS Offline
                        SGaistS Offline
                        SGaist
                        Lifetime Qt Champion
                        wrote on last edited by
                        #12

                        It's all in the source Luke ! ^^

                        Most of the documentation is written in the sources themselves or in .doc files. Here you just need a clone of qtbase then edit qstandardpaths.cpp. When in doubt about the location of a piece of documentation I just run grep or ag on the source with one of the phrase to get the right file to edit.

                        As for setting up your environment for submission, you have a detailed getting started guide here.

                        Interested in AI ? www.idiap.ch
                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                        raven-worxR 1 Reply Last reply
                        2
                        • SGaistS SGaist

                          It's all in the source Luke ! ^^

                          Most of the documentation is written in the sources themselves or in .doc files. Here you just need a clone of qtbase then edit qstandardpaths.cpp. When in doubt about the location of a piece of documentation I just run grep or ag on the source with one of the phrase to get the right file to edit.

                          As for setting up your environment for submission, you have a detailed getting started guide here.

                          raven-worxR Offline
                          raven-worxR Offline
                          raven-worx
                          Moderators
                          wrote on last edited by
                          #13

                          @SGaist said in qFile doesn't open on iOS:

                          It's all in the source Luke ! ^^

                          may the source be with you! :)

                          --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                          If you have a question please use the forum so others can benefit from the solution in the future

                          1 Reply Last reply
                          0
                          • J.HilkJ Offline
                            J.HilkJ Offline
                            J.Hilk
                            Moderators
                            wrote on last edited by
                            #14

                            I'll like to add some additional informations, that I encountered, in case someone comes onto this thread.

                            On Ios, since iOS 8.0, the absolute Path actually changes with each recompile/update.

                            That means, if you store the absolute path somewhere, e.g in your settings, and you recompile your appliaction, you won't find the file again.

                            This however does not mean, the file got deleted. It is still at QStandardPaths::standardLocations(QStandardPaths::AppDataLocation)

                            So instead of storing the absolute path, store the ´filename+extension´ and the enum QStandardPaths::StandardLocation and reconstruct the path from there.


                            Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                            Q: What's that?
                            A: It's blue light.
                            Q: What does it do?
                            A: It turns blue.

                            1 Reply Last reply
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