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Files Storage

About assets

You can make use of Asset to store file references such as images and videos on the database. An asset can only be saved with a record but not as a standalone upload. Skygear automatically uploads the files to a S3 bucket assigned to your app. You can also use your own file storage bucket. More settings can be found at the Developer Portal.

Creating an asset

For example, you want to allow users to upload an image as an image to his SKYRecord. Once the user has selected the image to upload, you can save it by:

- (void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary<NSString *, id> *)info
{
    UIImage *image = info[UIImagePickerControllerOriginalImage];
    SKYAsset *asset = [SKYAsset assetWithName:@"profile-picture"
                                         data:UIImagePNGRepresentation(image)];
    asset.mimeType = @"image/png";

    SKYContainer *container = [SKYContainer defaultContainer];
    [container.privateCloudDatabase uploadAsset:asset completionHandler:^(SKYAsset *asset, NSError *error) {
        if (error) {
            NSLog(@"error uploading asset: %@", error);
            return;
        }

        self.photoRecord[@"image"] = asset;
        [container.privateCloudDatabase saveRecord:self.photoRecord completion:nil];
    }];
}

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
    if let url = info[UIImagePickerControllerReferenceURL] as? URL {
        let asset = SKYAsset(name: "profile-picture", fileURL: url)
        asset.mimeType = "image/png"

        let container = SKYContainer.default()
        container.privateCloudDatabase.uploadAsset(asset, completionHandler: { (asset, error) in
            if error != nil {
                print ("error uploading asset: \(error)")
                return
            }

            self.photoRecord?.setObject(asset, forKey: "image" as NSCopying!)
            container.privateCloudDatabase.save(self.photoRecord, completion: nil)
        })
    }
}

In Skygear SDK 1.6 or later, assets are uploaded automatically when you save a record, so you do not need to call uploadAsset separately.

Asset names will never collide. i.e. you can upload multiple assets with the same asset name.

asset.name is rewritten after the asset being uploaded.

NSString *newName = asset.name;
// The name is changed to "c36e803a-f333-47bf-a3e9-4d52b660a71a-profile-picture"
// from "profile-picture"

let newName = asset.name
// The name is changed to "c36e803a-f333-47bf-a3e9-4d52b660a71a-profile-picture"
// from "profile-picture"

Querying an asset

SKYAsset.url will be populated with an expiry URL after fetching / querying the record from server.

[[[SKYContainer defaultContainer] privateCloudDatabase] fetchRecordWithID:photoRecordID completionHandler:^(SKYRecord *photo, NSError *error) {
    if (error) {
        NSLog(@"error fetching photo: %@", error);
        return;
    }

    SKYAsset *asset = photo[@"image"];
    NSURL *url = asset.url;
    // do something with the url
}];

SKYContainer.default().privateCloudDatabase.fetchRecord(with: photoRecordID) { (photo, error) in
    if error != nil {
        print ("error fetching photo: \(error)")
        return
    }

    if let asset = photo?.object(forKey: "image") as? SKYAsset{
        let url = asset.url
        // do something with the url
    }
}

Frequently Asked Questions

Is there limit to file upload on Skygear Cloud?

Currently, It is possible to upload file to Skygear Cloud with a maximum size of 50MB.

Is it possible to add CORS settings to file upload?

If you use Skygear Cloud, a CORS settings of * (any origin) is added to all files, so you can fetch your assets using scripts from any origin. If you have your own S3 bucket, follow the Cross-Origin Resource Sharing guide. when downloading files