2020欧洲杯直播投注

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Rapid App Development with Live Reload

So far, we’ve seen how easy it is to develop a cross-platform app that works everywhere. The development experience is pretty quick, but what if I told you there was a way to go faster?

We can use the Ionic CLI’s Live Reload functionality to boost our productivity when building Ionic apps. When active, Live Reload will reload the browser and/or WebView when changes in the app are detected.

Live Reload

Remember ionic serve? That was Live Reload working in the browser, allowing us to iterate quickly.

2020欧洲杯直播投注We can also use it when developing on iOS and Android devices. This is particularly useful when writing code that interacts with native plugins. Since we need to run native plugin code on a device in order to verify that it works, having a way to quickly write code, build and deploy it, then test it is crucial to keeping up our development speed.

Let’s use Live Reload to implement photo deletion, the missing piece of our Photo Gallery feature. Select your platform of choice (iOS or Android) and connect a device to your computer. Next, run either command in a terminal, based on your chosen platform:

$ ionic cap run ios -l --external

$ ionic cap run android -l --external

2020欧洲杯直播投注The Live Reload server will start up, and the native IDE of choice will open if not opened already. Within the IDE, click the Play button to launch the app onto your device.

Deleting Photos

With Live Reload running and the app is open on your device, let’s implement photo deletion functionality. Open Tab2.tsx then import useState from React and Photo from the usePhotoGallery hook:

import React, { useState } from 'react';
import { usePhotoGallery, Photo } from '../hooks/usePhotoGallery';
// other imports

Next, reference the deletePhoto function, which we'll create soon:

const { photos, takePhoto, deletePhoto } = usePhotoGallery();

2020欧洲杯直播投注Next, add a state value to store information about the photo to delete:

const [photoToDelete, setPhotoToDelete] = useState<Photo>();

When a user clicks on an image, we will show the action sheet by changing the state value to the photo. Update the <IonImg> element to:

<IonImg onClick={() => setPhotoToDelete(photo)} 
        src={photo.base64 ?? photo.webviewPath} />

Next, add an IonActionSheet dialog with the option to either delete the selected photo or cancel (close) the dialog. We will set the isOpen property based on if photoToDelete has a value or not.

In the JSX, put the following component before the closing </IonContent> tag.

<IonActionSheet
  isOpen={!!photoToDelete}
  buttons={[{
    text: 'Delete',
    role: 'destructive',
    icon: trash,
    handler: () => {
      if (photoToDelete) {
        deletePhoto(photoToDelete);
        setPhotoToDelete(undefined);
      }
    }
  }, {
    text: 'Cancel',
    icon: close,
    role: 'cancel'
  }]}
  onDidDismiss={() => setPhotoToDelete(undefined)}
/>

Above, we added two options: Delete that calls deletePhoto function (to be added next) and Cancel2020欧洲杯直播投注, which when given the role of “cancel” will automatically close the action sheet. It's also important to set the onDidDismiss function and set our photoToDelete back to undefined when the modal goes away. That way, when another image is clicked, the action sheet notices the change in the value of photoToDelete.

Next, we need to implement the deletePhoto method that will come from the usePhotoGallery2020欧洲杯直播投注 hook. Open the file and paste in the following function in the hook:

const deletePhoto = async (photo: Photo) => {
  // Remove this photo from the Photos reference data array
  const newPhotos = photos.filter(p => p.filepath !== photo.filepath);

  // Update photos array cache by overwriting the existing photo array
  set(PHOTO_STORAGE, JSON.stringify(newPhotos));

  // delete photo file from filesystem
  const filename = photo.filepath.substr(photo.filepath.lastIndexOf('/') + 1);
  await deleteFile({
    path: filename,
    directory: FilesystemDirectory.Data
  });
  setPhotos(newPhotos);
};

2020欧洲杯直播投注The selected photo is removed from the Photos array first. Then, we use the Capacitor Storage API to update the cached version of the Photos array. Finally, we delete the actual photo file itself using the Filesystem API.

Make sure to return the deletePhoto2020欧洲杯直播投注 function so it is as a part of the hook API that we expose:

return {
  deletePhoto,
  photos,
  takePhoto
};

2020欧洲杯直播投注Save this file, then tap on a photo again and choose the “Delete” option. This time, the photo is deleted! Implemented much faster using Live Reload. 💪

What’s Next?

2020欧洲杯直播投注Congratulations! You created a complete cross-platform Photo Gallery app that runs on the web, iOS, and Android.

There are many paths to follow from here. Try adding another Ionic UI component to the app, or more native functionality2020欧洲杯直播投注. The sky’s the limit.

Happy app building! 💙

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