FeedCollectionViewController

A simple interface for creating data feeds so that data can be loaded
dynamically as the user scrolls. This is inspired by scrolling through photos
on Facebook or Instagram.

^{Images taken from the example project that uses colours in place of real content.}

FeedCollectionViewController is a generic interface for setting up a simple
feed, whereas ImageFeedCollectionViewController is specifically set up for
images. ImageFeedCollectionViewController uses a fork
of IDMPhotoBrowser,
so that tapping on images lets you scroll through photos indefinitely.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.
The example project demonstrates the functionality without using any actual content, it creates
coloured images to illustrate its use with a large amount of content.

Installation

FeedCollectionViewController is available through CocoaPods. To install
FeedCollectionViewController, simply add the following line to your Podfile:

pod "FeedCollectionViewController"

To install ImageFeedCollectionViewController, simply add the following line to
your Podfile:

pod "ImageFeedCollectionViewController"

Usage

The set up is quite similar to UICollectionViewController, you must specify a
reuse identifier and a UICollectionViewCell that should take its data from an
implemented CellData.

FeedCollectionViewController:

    open func getReuseIdentifier(cell:CellData) -> String {
        // specifies the identifier of the cell, this can differ per cell
    }

    open func getCells(start:Int, callback: @escaping (([CellData]) -> Void)) {
        // get new cell data, this does not actually mean the cell is being shown
        // call `callback` with the new data. `start` is the query starting position
    }

    open func loadCell(cellView: UICollectionViewCell, cell:CellData) {
        // load the cell since it's now actually shown
    }

ImageFeedCollectionViewController:

    open func getImageReuseIdentifier(cell: ImageCellData) -> String {
        // specifies the identifier of the cell, this can differ per cell
    }

    open func getImageCells(start:Int, callback: @escaping (([ImageCellData]) -> Void)) {
        // get new cell data, this does not actually mean the cell is being shown
        // call `callback` with the new data. `start` is the query starting position
    }

    open func loadImageCell(cellView: UICollectionViewCell, cell:ImageCellData) {
        // load the cell (ie. a thumbnail) since it's now actually shown
    }

You must have a custom ImageCellData implementation, this subclasses
IDMPhoto, which will be used in the photo browser. To use with image
URLs use super.init(url: imageUrl) within ImageCellData.

To customise views in the ImageFeedCollectionViewController, you must
implement SingleImageView and override relevant methods. The relevant
methods are the same as those in IDMCaptionView.

    open override func setupCaption() {
        // Setup caption views
    }

    open override func sizeThatFits(_ size: CGSize) -> CGSize {
        // Return the height of the view, the width will be ignored
    }

To receive updates when the displayed photo changes, override didShowPhoto(cell:ImageCellData)

To receive image download failures from the photo browser, you can override
imageFailed(cell:ImageCellData).

To customise the photo browser's toolbar, you can override
setupToolbar(toolbar:UIToolbar, cell:ImageCellData) and make modifications
as needed.

Custom error messages and views are also available for feed retrieval failure
through getErrorMessage or showErrorText.

Testing

Testing is done through FBSnapshotTestCase, there are test result files included
in Example/Tests/ReferenceImages_64/FeedCollectionViewController_Tests.Tests.
These were run with iPhone SE Simulator, however you can re-run on your own
device by enabling recordMode in setUp() and then re-running the test with
it off.

Todo

• Better tests. Currently I've only implemented snapshot tests
• The snapshot tests are based on timers where something like
  EarlGrey would be better suited but I
  had trouble with timeout errors when attempting this

Author

Oliver O'Neill

License

FeedCollectionViewController is available under the MIT license. See the LICENSE file for more info.