docs.sheetjs.com/docz/docs/03-demos/19-mobile.md

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19	iOS and Android Apps

Many mobile app frameworks mix JavaScript / CSS / HTML5 concepts with native extensions and libraries to create a hybrid development experience. Developers well-versed in web technologies can now build actual mobile applications that run on iOS and Android!

:::warning

The ecosystem has broken backwards-compatibility many times!

iOS and Android, as well as the underlying JavaScript frameworks, make breaking changes regularly. The demos were tested against emulators / real devices at some point in time. A framework or OS change can render the demos inoperable.

Each demo section will mention test dates and platform versions.

:::

The "JavaScript Engines" section includes samples for JavaScript engines used in the mobile app frameworks. SheetJS libraries have been tested in the relevant engines and should "just work" with some caveats.

:::caution readFile and writeFile

XLSX.readFile and XLSX.writeFile do not work in mobile apps! The demos include platform-specific details for fetching file data for XLSX.read and writing file data generated by XLSX.write.

Some platforms provide this functionality as part of the standard library. Other platforms, including React Native, do not. When the platform does not provide, usually there are third-party modules to provide needed functionality.

:::

NativeScript

:::note

This demo was tested on an Intel Mac on 2022 August 10. NativeScript version (as verified with ns --version) is 8.3.2. The iOS simulator runs iOS 15.5 on an iPhone SE 3rd generation.

:::

:::warning Binary Data issues

NativeScript will not safely transmit binary or UTF8 strings. XLSB, NUMBERS, XLSX, XLS, ODS, SYLK, and DBF exports are known to be mangled.

This is a known NativeScript bug

This demo will focus on ASCII CSV files. Once the bug is resolved, XLSX and other formats will be supported.

:::

The @nativescript/core/file-system package provides classes for file access.

Integration Details

Reading and writing data require a file handle. The following snippet searches typical document folders for a specified filename:

import { File, Folder, knownFolders, path } from '@nativescript/core/file-system';

function get_handle_for_filename(filename: string): File {
  const target: Folder = knownFolders.documents() || knownFolders.ios.sharedPublic();
  const url: string = path.normalize(target.path + "///" + filename);
  return File.fromPath(url);
}

The encoding ISO_8859_1 spiritually resembles the "binary" SheetJS type

Reading data

File#readText(encoding.ISO_8859_1) returns strings compatible with "binary"

/* get binary string */
const bstr: string = await file.readText(encoding.ISO_8859_1);

/* read workbook */
const wb = read(bstr, { type: "binary" });

Writing data

File#writeText with the ISO_8859_1 encoding accepts "binary" strings with the caveat listed in the warning at the top of this section:

/* generate binary string */
const bstr: string = write(wb, { bookType: 'csv', type: 'binary' });

/* attempt to save binary string to file */
await file.writeText(bstr, encoding.ISO_8859_1);

Demo

The demo builds off of the NativeScript + Angular example. Familiarity with with Angular and TypeScript is assumed.

Complete Example (click to show)

0. Follow the official Environment Setup instructions (tested with "macOS + iOS")

1. Create a skeleton NativeScript + Angular app:

ns create SheetJSNS --ng

2. Launch the app in the iOS simulator to verify that the demo built properly:

cd SheetJSNS
ns run ios

(this may take a while)

Once the simulator launches and the test app is displayed, end the script by selecting the terminal and entering the key sequence CTRL + C

3. From the project folder, install the library:

npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz

4. To confirm the library was loaded, change the title to show the version. The differences are highlighted.

src/app/item/items.component.ts imports the version string to the component:

// highlight-next-line
import { version } from 'xlsx';
import { Component, OnInit } from '@angular/core'

import { Item } from './item'
import { ItemService } from './item.service'

@Component({
  selector: 'ns-items',
  templateUrl: './items.component.html',
})
export class ItemsComponent implements OnInit {
  items: Array<Item>
  // highlight-next-line
  version = `SheetJS - ${version}`;

  constructor(private itemService: ItemService) {}

  ngOnInit(): void {
    this.items = this.itemService.getItems()
  }
}

src/app/item/items.component.html references the version in the title:

<!-- highlight-next-line -->
<ActionBar [title]="version"></ActionBar>

<GridLayout>
  <ListView [items]="items">
    <ng-template let-item="item">
      <StackLayout [nsRouterLink]="['/item', item.id]">
        <Label [text]="item.name"></Label>
      </StackLayout>
    </ng-template>
  </ListView>
</GridLayout>

Relaunch the app with ns run ios and the title bar should show the version.

5. Add the Import and Export buttons to the template:

<ActionBar [title]="version"></ActionBar>

<!-- highlight-start -->
<StackLayout>
  <StackLayout orientation="horizontal">
    <Button text="Import File" (tap)="import()" style="padding: 10px"></Button>
    <Button text="Export File" (tap)="export()" style="padding: 10px"></Button>
  </StackLayout>
<!-- highlight-end -->
  <ListView [items]="items">
    <ng-template let-item="item">
      <StackLayout [nsRouterLink]="['/item', item.id]">
        <Label [text]="item.name"></Label>
      </StackLayout>
    </ng-template>
  </ListView>
<!-- highlight-next-line -->
</StackLayout>

// highlight-start
import { version, utils, read, write } from 'xlsx';
import { Dialogs } from '@nativescript/core';
import { encoding } from '@nativescript/core/text';
import { File, Folder, knownFolders, path } from '@nativescript/core/file-system';
// highlight-end
import { Component, OnInit } from '@angular/core'

import { Item } from './item'
import { ItemService } from './item.service'

// highlight-start
function get_handle_for_filename(filename: string): [File, string] {
  const target: Folder = knownFolders.documents() || knownFolders.ios.sharedPublic();
  const url: string = path.normalize(target.path + "///" + filename);
  return [File.fromPath(url), url];
}
// highlight-end

@Component({
  selector: 'ns-items',
  templateUrl: './items.component.html',
})
export class ItemsComponent implements OnInit {
  items: Array<Item>
  version: string = `SheetJS - ${version}`;

  constructor(private itemService: ItemService) {}

  ngOnInit(): void {
    this.items = this.itemService.getItems()
  }

  // highlight-start
  /* Import button */
  async import() {
  }

  /* Export button */
  async export() {
  }
  // highlight-end
}

Restart the app process and two buttons should show up at the top:

6. Implement import and export:

import { version, utils, read, write } from 'xlsx';
import { Dialogs } from '@nativescript/core';
import { encoding } from '@nativescript/core/text';
import { File, Folder, knownFolders, path } from '@nativescript/core/file-system';
import { Component, OnInit } from '@angular/core'

import { Item } from './item'
import { ItemService } from './item.service'

function get_handle_for_filename(filename: string): [File, string] {
  const target: Folder = knownFolders.documents() || knownFolders.ios.sharedPublic();
  const url: string = path.normalize(target.path + "///" + filename);
  return [File.fromPath(url), url];
}

@Component({
  selector: 'ns-items',
  templateUrl: './items.component.html',
})
export class ItemsComponent implements OnInit {
  items: Array<Item>
  version: string = `SheetJS - ${version}`;

  constructor(private itemService: ItemService) {}

  ngOnInit(): void {
    this.items = this.itemService.getItems()
  }

  /* Import button */
  async import() {
    // highlight-start
    /* find appropriate path */
    const [file, url] = get_handle_for_filename("SheetJSNS.csv");

    try {
      /* get binary string */
      const bstr: string = await file.readText(encoding.ISO_8859_1);

      /* read workbook */
      const wb = read(bstr, { type: "binary" });

      /* grab first sheet */
      const wsname: string = wb.SheetNames[0];
      const ws = wb.Sheets[wsname];

      /* update table */
      this.items = utils.sheet_to_json<Item>(ws);
      Dialogs.alert(`Attempting to read to ${filename} in ${url}`);
    } catch(e) { Dialogs.alert(e.message); }
    // highlight-end
  }

  /* Export button */
  async export() {
    // highlight-start
    /* find appropriate path */
    const [file, url] = get_handle_for_filename("SheetJSNS.csv");

    try {
      /* create worksheet from data */
      const ws = utils.json_to_sheet(this.items);

      /* create workbook from worksheet */
      const wb = utils.book_new();
      utils.book_append_sheet(wb, ws, "Sheet1");

      /* generate binary string */
      const wbout: string = write(wb, { bookType: 'csv', type: 'binary' });

      /* attempt to save binary string to file */
      await file.writeText(wbout, encoding.ISO_8859_1);
      Dialogs.alert(`Wrote to ${filename} in ${url}`);
    } catch(e) { Dialogs.alert(e.message); }
    // highlight-end
  }
}

Restart the app process.

Testing

The app can be tested with the following sequence in the simulator:

• Hit "Export File". A dialog will print where the file was written

• Open that file with a text editor. It will be a 3-column CSV:

id,name,role
1,Ter Stegen,Goalkeeper
3,Piqué,Defender
4,I. Rakitic,Midfielder
...

After the header row, add the line 0,SheetJS,Library:

id,name,role
0,SheetJS,Library
1,Ter Stegen,Goalkeeper
3,Piqué,Defender
...

• Hit "Import File". A dialog will print the path of the file that was read. The first item in the list will change:

Quasar

:::note

This demo was tested on an Intel Mac on 2022 August 14. Quasar version 2.7.7. The iOS simulator runs iOS 15.5 on an iPhone SE 3rd generation.

:::

This demo will focus on VueJS and Cordova with the Quasar Vite starter project.

Integration Details

The complete solution uses cordova-plugin-file for file operations. It can be installed like any other Cordova plugin:

cd src-cordova
cordova plugin add cordova-plugin-file
cd ..

Reading data

The q-file component presents an API reminiscent of File Input elements:

<q-file label="Load File" filled label-color="orange" @input="updateFile"/>

When binding to the input element, the callback receives an Event object:

import { read } from 'xlsx';

// assuming `todos` is a standard VueJS `ref`
async function updateFile(v) { try {
  // `v.target.files[0]` is the desired file object
  const files = (v.target as HTMLInputElement).files;
  if(!files || files.length == 0) return;

  // read first file
  const wb = read(await files[0].arrayBuffer());

  // get data of first worksheet as an array of objects
  const data = utils.sheet_to_json(wb.Sheets[wb.SheetNames[0]]);

  // update state
  todos.value = data.map(row => ({id: row.Index, content: row.Name}));

} catch(e) { console.log(e); } }

Writing data

The API is shaped like the File and Directory Entries API. For clarity, since the code is a "pyramid of doom", the error handlers are omitted:

import { write } from 'xlsx';

// on iOS and android, `XLSX.write` with type "buffer" returns a `Uint8Array`
const u8: Uint8Array = write(wb, {bookType: "xlsx", type: "buffer"});
// Request filesystem access for persistent storage
window.requestFileSystem(window.PERSISTENT, 0, function(fs) {
  // Request a handle to "SheetJSQuasar.xlsx", making a new file if necessary
  fs.root.getFile("SheetJSQuasar.xlsx", {create: true}, entry => {
    // Request a FileWriter for writing data
    entry.createWriter(writer => {
      // The FileWriter API needs an actual Blob
      const data = new Blob([u8], {type: "application/vnd.ms-excel"});
      // This callback is called if the write is successful
      writer.onwriteend = () => {
        // TODO: show a dialog
      };
      // writer.onerror will be invoked if there is an error in writing

      // write the data
      writer.write(data);
    });
  });
});

Demo

The demo builds off of the Vite example. Familiarity with VueJS and TypeScript is assumed.

Complete Example (click to show)

0. Ensure all of the dependencies are installed. Install the CLI globally:

npm i -g @quasar/cli cordova

(you may need to run sudo npm i -g if there are permission issues)

1. Create a new app:

npm init quasar

When prompted:

• "What would you like to build?": App with Quasar CLI
• "Project folder": SheetJSQuasar
• "Pick Quasar version": Quasar v2 (Vue 3 | latest and greatest)
• "Pick script type": Typescript
• "Pick Quasar App CLI variant": Quasar App CLI with Vite
• "Package name": (just press enter, it will use the default sheetjsquasar
• "Project product name": SheetJSQuasar
• "Project description": SheetJS + Quasar
• "Author": (just press enter, it will use your git config settings)
• "Pick a Vue component style": Composition API
• "Pick your CSS preprocessor": None
• "Check the features needed for your project": Deselect everything
• "Install project dependencies": No

2. Install dependencies:

cd SheetJSQuasar
npm i
npm i --save https://cdn.sheetjs.com/xlsx-latest/xlsx-latest.tgz

3. Set up Cordova:

quasar mode add cordova

When prompted, enter the app id org.sheetjs.quasar.

It will create a new src-cordova folder. Continue in that folder:

cd src-cordova
cordova platform add ios
cordova plugin add cordova-plugin-wkwebview-engine
cordova plugin add cordova-plugin-file

:::note

If there is an error Could not load API for iOS project, it needs to be reset:

cordova platform rm ios
cordova platform add ios
cordova plugin add cordova-plugin-file

:::

Return to the project directory:

cd ..

4. Start the dev server:

quasar dev -m ios

:::caution

If the app is blank, delete the app and close the simulator, then restart dev

:::

5. Add the Dialog plugin to quasar.config.js:

      // Quasar plugins
      // highlight-next-line
      plugins: ['Dialog']

6. In the template section of src/pages/IndexPage.vue, add a Save button and a Load file picker component at the bottom of the page:

    <!-- highlight-start -->
    <q-btn-group>
      <q-file label="Load File" filled label-color="orange" @input="updateFile"/>
      <q-btn label="Save File" @click="saveFile" />
    </q-btn-group>
    <!-- highlight-end -->
  </q-page>
</template>

This uses two functions that should be added to the component script:

    const meta = ref<Meta>({
      totalCount: 1200
    });
// highlight-start
    function saveFile() {
    }
    async function updateFile(v) {
    }
    return { todos, meta, saveFile, updateFile };
// highlight-end
  }
});

The app should now show two buttons at the bottom:

:::caution

If the app is blank or not refreshing, delete the app and close the simulator, then restart the dev process.

:::

7. Wire up the updateFile function:

import { defineComponent, ref } from 'vue';
// highlight-start
import { read, write, utils } from 'xlsx';
import { useQuasar } from 'quasar';
// highlight-end

export default defineComponent({
// ...
// highlight-start
    const $q = useQuasar();
    function dialogerr(e) { $q.dialog({title: "Error!", message: e.message || String(e)}); }
// highlight-end
    function saveFile() {
    }
    async function updateFile(v) {
// highlight-start
      try {
        const files = (v.target as HTMLInputElement).files;
        if(!files || files.length == 0) return;

        const wb = read(await files[0].arrayBuffer());

        const data = utils.sheet_to_json(wb.Sheets[wb.SheetNames[0]]);
        todos.value = data.map(row => ({id: row.Index, content: row.Name}));
      } catch(e) { dialogerr(e); }
// highlight-end
    }

To test that reading works:

• Download https://sheetjs.com/pres.numbers
• In the simulator, click the Home icon to return to the home screen
• Click on the "Files" icon
• Click and drag pres.numbers from a Finder window into the simulator.

• Make sure "On My iPhone" is highlighted and select "Save"
• Click the Home icon again then select the SheetJSQuasar app
• Click the "Load" button, then select "Choose File" and select pres:

Once selected, the screen should refresh with new contents:

8. Wire up the saveFile function:

    function saveFile() {
// highlight-start
      /* generate workbook from state */
      const ws = utils.json_to_sheet(todos.value);
      const wb = utils.book_new();
      utils.book_append_sheet(wb, ws, "SheetJSQuasar");
      const u8: Uint8Array = write(wb, {bookType: "xlsx", type: "buffer"});

      /* save to file */
      window.requestFileSystem(window.PERSISTENT, 0, function(fs) {
        try {
          fs.root.getFile("SheetJSQuasar.xlsx", {create: true}, entry => {
            const msg = `File stored at ${$q.cordova.file.documentsDirectory} ${entry.fullPath}`;
            entry.createWriter(writer => {
              try {
                const data = new Blob([u8], {type: "application/vnd.ms-excel"});
                writer.onwriteend = () => {
                  try {
                    $q.dialog({title: "Success!", message: msg});
                  } catch(e) { dialogerr(e); }
                };
                writer.onerror = dialogerr;
                writer.write(data);
              } catch(e) { dialogerr(e); }
            }, dialogerr);
          }, dialogerr);
        } catch(e) { dialogerr(e) }
      }, dialogerr);
// highlight-end
    }

The page should revert to the old contents.

To test that writing works:

• Click "Save File". You will see a popup with a location:

• Find the file and verify the contents are correct. Run in a new terminal:

find ~/Library/Developer/CoreSimulator -name SheetJSQuasar.xlsx |
  while read x; do echo "$x"; npx xlsx-cli "$x"; done

Since the contents reverted, you should see

SheetJSQuasar
id,content
1,ct1
2,ct2
3,ct3
4,ct4
5,ct5

• Use "Load File" to select pres.numbers again. Wait for the app to refresh.

• Click "Save File", then re-run the command:

find ~/Library/Developer/CoreSimulator -name SheetJSQuasar.xlsx |
  while read x; do echo "$x"; npx xlsx-cli "$x"; done

The contents from pres.numbers should show up now, with a new header row:

SheetJSQuasar
id,content
42,Bill Clinton
43,GeorgeW Bush
44,Barack Obama
45,Donald Trump
46,Joseph Biden