WALS Collection - Part 1 |LINK|
Ever since iOS 6, developers have been able to use collection views and to build interesting custom layouts by subclassing the UICollectionViewLayout or UICollectionViewFlowLayout classes. I even wrote an article about building custom collection view layouts a while ago. Today, I would like to introduce you to a new way of defining collection view layouts called compositional layouts. We're going to build the two layouts shown in the following image:
WALS Collection - Part 1
A very common use of collection views is to display a grid layout. It's so common that Apple has included a grid layout called UICollectionViewFlowLayout with iOS since they introduced UICollectionView in iOS 6. Since it's such a familiar and relatively simple layout, I want to explore the basics of UICollectionViewCompositionalLayout with you by using it to build a grid. I'm going to assume that you have already got a collection view setup, possibly with a diffable data source. If you want to follow along with the code samples in this post, I would recommend that you always put your compositional layout code in a method, as I will soon demonstrate. You can then assign the layout to your collection view by writing the following in your viewDidLoad() method:
If you would assign the layout that's generated by the createCompositionalLayout() method I just showed you to a collection view's collectionViewLayout property, you would get a very similar looking grid as a result. The items are a bit cramped though, so let's explore some of the spacing options we have.
Note that we define item spacing on the group that contains the items, and group spacing on the section that contains the groups. And also note that the item spacing is defined as .fixed(15) in this case. This means that groups will always position their items with 15 points between them. You can also use .flexible() to allow the group to determine the best spacing between items based on its size, and the size of the items that it's positioning. The group will use the value of its flexible spacing as the minimum spacing between items; your items might be positioned further apart from each other than you specified, but never closer to each other.
At the beginning of this article, I told you that I would show you how to build two different layouts. One of these two layouts contains section headers. So let's see how you can add section headers to your compositional collection view layout. If you're following along with the code I'm presenting in this article, you can use the following code snippet in the context of your grid layout, or any other compositional layout you might already have:
The first line of the preceding snippet should look familiar to you. The size of a collection view header is defined in exactly the same way as the size for items and groups. The header is defined as an instance of NSCollectionLayoutBoundarySupplementaryItem. Headers and footers are both different types of supplementary views, so they are defined in the exact same way. Depending on the value you pass to the alignment argument in the NSCollectionLayoutBoundarySupplementaryItem initializer, the supplementary view will act as a header, footer or just a decorative view. Also, note that there is an elementKind argument. This argument is a string identifier, similar to a cell reuse identifier that you use in your collection view data source when it's asked to provide a supplementary view.
Note: Since this post is not about setting up a collection view data source, I'm not going to explain section headers in depth. In short, you need to implement the collectionView(_:viewForSupplementaryElementOfKind:at:) method from the UICollectionViewDataSource protocol. You also need to register a UICollectionViewCell subclass on your collection view using the collection view's register(_:forSupplementaryViewOfKind:withReuseIdentifier:) method. This method is very similar to registering a collection view cell in code, except you also supply the element kind string identifier.
That wraps up the first collection view layout I wanted to show you! We began with a simple grid, and by changing a couple of numbers, adding a header and setting a property on our sections, we now have a layout that can scroll horizontally and vertically. It's truly amazing how little code we needed, especially when compared with the code we would have to write without compositional layouts.
Today's article introduced the new UICollectionViewCompositionalLayout class. You learned that this class allows you to specify complicated collection view layouts using four simple building blocks; items, groups, sections and the layout itself. With these blocks you can build layouts that would be a nightmare to implement using the good old UICollectionViewFlowLayout and the code to do this is simple and concise.
You saw how to build a collection view layout that positions its sections vertically, and the items within the section can be scrolled through horizontally. You learned that this is called orthogonal scrolling, and it can be enabled with just a single line of code. You also saw how you can nest groups to build a somewhat irregular looking layout that's very interesting visually.
Starting with the 2013 edition of WALS, we will release and publish sets of corrections periodically. Thus, any citation of WALS Online 2013 should include the particular version, as listed on Zenodo.
You can search for references through the item "References", and once you have navigated to a particular feature, you see a second navigation bar with citation information and various export options.
The study was performed thanks to the financial support of the Quebec Ministry of Health and Social Services, GlaxoSmithKline, and Pfizer. Sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of data; and preparation of the manuscript.
The double municipality had been founded in 1948 of the places Wals and Siezenheim. In the same year the arm had been conferred. The population figure rose up from 1,000 inhabitants in 1947 to approximately 11,000 in 2001. Previous Wals was part of the separate municipality Siezenheim, but even so Liefering and a giant part of Taxach.
The municipality is located between the city of Salzburg in the east and the Austrian border with Germany in the west. It was established in 1948 by the merger of Wals and Siezenheim, after parts of its territories had been incorporated into the Salzburg city limits. The whole municipal area belongs to the suburbs of Salzburg, however, no further amalgamation efforts have been made so far. It currently comprises the cadastral communities of Wals I, Liefering I, Siezenheim I, and Gois.
The tricky part here is that the WALS module is, I believe, using an older paradigm of TensorFlow, where the serving_input_fn argument is expecting a callable function that returns an InputFnOps. However, the more updated Estimators, such as this one, expects a function that returns a tf.estimator.export.ServingInputReceiver or tf.estimator.export.TensorServingInputReceiver. I admit I'm not completely fluent in input functions of TensorFlow yet, but any help for my specific use case of saving my WALS estimator will be greatly appreciated. Thanks!
Cooper and her colleagues use implementation science and community-based participatory research to develop health programs. Implementation science, a burgeoning public-health field that is gaining NIH interest and funding support, is the scientific study of methods and strategies needed to implement evidence-based practices. Cooper seeks to understand health-care organization and community partner actions and how political, environmental, and social variables sustain or prevent the uptake of evidence-based programs.
The Amon Carter Museum of American Art is supported, in part, by the generosity of Carter members and donors, and by grants from Arts Fort Worth, the City of Fort Worth, the Fort Worth Tourism Public Improvement District, and the Texas Commission on the Arts.
The National Gallery has endeavoured to make as many images of the collection as possible available for non-commercial use. However, an image of this painting is not available to download. This may be due to third party copyright restrictions.
Ribonucleic acids (RNAs) are ancient macromolecules, likely the first molecules capable of heredity. Although RNAs of different sizes, sequences, and functions have been studied intensely over the past six decades, particular attention has been given to messenger (m)RNAs, the templates for protein synthesis. Interest in noncoding (nc)RNAs, which comprise a far larger and more diverse segment of the RNA family, has also escalated in recent years, especially as many ncRNAs, such as microRNAs and long noncoding (lnc)RNAs, directly influence protein expression programs.
We are a community of educators working with learners from birth to adulthood. What brings us together is a passion for collaborative learning and in particular, lesson and learning study.As a member of WALS you will benefit from:-
Lesson Study as a tool for professional learning is now practised in many countries and it has helped schools around the world develop into learning communities. Our annual conferences bring together researchers, school leaders and teachers from various countries to share their experience and practice of lesson studies. They also provide opportunities for participants to discuss current and enduring issues pertaining to teaching, learning and research on Lesson Study.
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