Swift combine create custom publisher

Combine is Swift declarative framework for processing values over time [1]. It imposes functional reactive paradigm of programming, which is different from the object-oriented one that prevails in iOS development community. Reactive means programming with asynchronous streams of values. The Reactive Manifesto tells more about it. Functional programming is all about programming with functions.

In Swift functions can be passed as arguments to other functions, returned from functions, stored in variables and data structures and built at run time as closures.

In declarative programming style you describe what the program doeswithout describing the flow of control. In imperative style you write how the program works by implementing and handling a series of tasks. Imperative programs rely primarily on state, which is usually modified with assignments. Programming with Swift Combine framework is both declarative, reactive and functional.

It involves chaining functions and passing values from one to the other. This creates the streams of values, flowing from the input to the output. A publisher can send values or terminate with either success or error. Output defines what kind of values a publisher can send. Failure defines the type of error it may fail with.

The receive subscriber: method connects a subscriber to a publisher. A subscriber can receive a value of type Input or a termination event with either success or Failure. Combine has two built-in subscribers: Subscribers. Sink and Subscribers. You can connect them by calling either of these methods on a publisher :.

After sending 1the publisher automatically finishes. We do not have to handle any errors, since Just cannot fail. Subject is a special kind of Publisher that can insert values, passed from the outside, into the stream.

A connection between a publisher and a subscriber is called subscription. The steps of such a connection define a publisher-subscriber life cycle. It prints log messages for all publishing events to console, which already can tell us a lot about the life cycle. This gives us a clue about publisher-subscriber life cycle.A publisher delivers elements to one or more Subscriber instances.

The publisher implements the receive subscriber: method to accept a subscriber. After this, the publisher can call the following methods on the subscriber:. The subscriber uses the subscription to demand elements from the publisher and can use it to cancel publishing. Every Publisher must adhere to this contract for downstream subscribers to function correctly.

Extensions on Publisher define a wide variety of operators that you compose to create sophisticated event-processing chains. Each operator returns a type that implements the Publisher protocol.

swift combine create custom publisher

Most of these types exist as extensions on the Publishers enumeration. Rather than implementing the Publisher protocol yourself, you can create your own publisher by using one of several types provided by the Combine framework:.

swift combine create custom publisher

Add the Published annotation to a property of one of your own types. See the Published type for an example of this approach. A publisher must declare the output type of elements it produces and the type of failure if any that may terminate publishing. Transforms elements from the upstream publisher by providing the current element to a closure along with the last value returned by the closure. Transforms elements from the upstream publisher by providing the current element to an error-throwing closure along with the last value returned by the closure.

Calls an error-throwing closure with each received element and publishes any returned optional that has a value. Collects all received elements, and emits a single array of the collection when the upstream publisher finishes.

Collects up to the specified number of elements, and then emits a single array of the collection. Applies a closure that accumulates each element of a stream and publishes a final result upon completion. Applies an error-throwing closure that accumulates each element of a stream and publishes a final result upon completion.

Publishes the maximum value received from the upstream publisher, using the provided ordering closure. Publishes the maximum value received from the upstream publisher, using the provided error-throwing closure to order the items. Publishes the minimum value received from the upstream publisher, using the provided error-throwing closure to order the items.

Publishes a Boolean value upon receiving an element that satisfies the throwing predicate closure. Publishes a single Boolean value that indicates whether all received elements pass a given predicate. Publishes a single Boolean value that indicates whether all received elements pass a given error-throwing predicate. Ignores elements from the upstream publisher until it receives an element from a second publisher. Omits elements from the upstream publisher until a given closure returns false, before republishing all remaining elements.

Omits elements from the upstream publisher until an error-throwing closure returns false, before republishing all remaining elements. Republishes elements while a error-throwing predicate closure indicates publishing should continue. Publishes only the last element of a stream that satisfies a predicate closure, after the stream finishes.

Publishes only the last element of a stream that satisfies an error-throwing predicate closure, after the stream finishes. Subscribes to an additional publisher and invokes a closure upon receiving output from either publisher. Subscribes to an additional publisher and publishes a tuple upon receiving output from either publisher. Subscribes to two additional publishers and invokes a closure upon receiving output from any of the publishers.

Subscribes to two additional publishers and publishes a tuple upon receiving output from any of the publishers. Subscribes to three additional publishers and invokes a closure upon receiving output from any of the publishers.Swift Publisher is a super-intuitive, all-purpose page layout and desktop publishing app for Mac.

Swift Publisher contains over templates of diverse print projects, including bi-fold and tri-fold brochures, catalogs, business cards, social media, disc labels and covers, address labels and much more. Additional free templates are also available. Swift Publisher comes with 2, free clipart images and image masks. A collection of 2D and 3D state of the art heading presets adds to the professional look of your page layout documents.

Want to create your own text styles? Art Text 3 integration will assist you with that Art Text 3 purchase required. With Swift Publisher for Mac you can view and edit two pages side-by-side. Specific to professional desktop publishing software, this functionality is very convenient for working with magazines, newspapers and other double-page layouts.

Found only in the best DTP apps, Master pages are a powerful tool for creating repeating content: headers, footers, page numbers and common background for your documents. Easily access your albums, collections and favorites from Apple Photos iPhoto, ApertureiTunes library or from any folder in the Finder. Regular text is added with an adjustable Text Box tool.

In addition, Swift Publisher has Circular Text and Vertical Text tools that are useful when designing discs and jewel case inserts. Set up and save your own text styles for any document just once and apply them with one click of the mouse. Using drawing tools, gradient fills, shadows, image tiling, over image masks, a built-in image editor and other tools, you'll find that the design solutions are endless. Text boxes can be linked to make your text flow from one text box into another, even when text boxes are on different pages.

That is great for complex, multi-column layouts such as self-publishing magazines and books. The program supports dynamic fields which pull data from Apple Contacts or a text file. You can use these to batch-print mailing and barcode labels, business cards or name badges. Swift Publisher supports a layer-based workflow for creating complex designs with no mess.

Layers have a dedicated tab in the Inspector, where you can also reorder them or make them invisible and non-printable. Swift Publisher supports hundreds of paper layouts for business cards, disc and shipping labels from Avery, Memorex, Neato and others and also facilitates the creation of custom layouts.

Opt for converting text to curves to avoid issues with fonts, when submitting a document to a print shop.

swift combine create custom publisher

Over pre-designed templates that you can customize and use for a quick solution. Printing booklets in Swift Publisher is simple thanks to the page imposition features. Use the Spread View mode to view and edit two pages side-by-side.A notification dispatch mechanism that enables the broadcast of information to registered observers. When an object adds itself as an observer, it specifies which notifications it should receive.

An object may therefore call this method several times in order to register itself as an observer for several different notifications. Each running app has a default notification center, and you can create new notification centers to organize communications in particular contexts. A notification center can deliver notifications only within a single program; if you want to post a notification to other processes or receive notifications from other processes, use Distributed Notification Center instead.

Adds an entry to the notification center's dispatch table that includes a notification queue and a block to add to the queue, and an optional notification name and sender. Adds an entry to the notification center's dispatch table with an observer and a notification selector, and an optional notification name and sender.

Removes all entries specifying a given observer from the notification center's dispatch table. Creates a notification with a given name, sender, and information and posts it to the notification center. Language: Swift Objective-C. Class Notification Center. SDKs iOS 2. Framework Foundation.

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Topics Getting the Default Notification Center. Adding and Removing Notification Observers. Removes matching entries from the notification center's dispatch table. Posting Notifications. Name, object : Any?

Creates a notification with a given name and sender and posts it to the notification center. Publishing Notifications to Combine. Name, object : Any Object? Publisher Returns a publisher that emits events when broadcasting notifications. Publisher A publisher that emits elements when broadcasting notifications. Relationships Inherits From. Conforms To. CVar Arg. See Also Notifications.Keep in touch and stay productive with Teams and Officeeven when you're working remotely.

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Could someone please give me some pointers on how to attempt the following. It's an unconventional way of using mail merge, maybe there is a better way. The application I am creating is designed to generate documents automatically. I am designing a front end in MS Accessto gather information from my customers, and then want to use Word to create perhaps as many as 20 documents, ranging from simple tables to 30 page technical documents.

I estimate needed about fields overall, obviously not all will be required in each document. This differs from a conventional mail merge, as it will typically involve only one record, and doesn't require address blocks, envelopes or labels. I need the strength of Word to produce professionally laid-out documents.

Swift Combine Framework Tutorial: Getting Started

The mail merge seems to be able to perform this task, although I am sure there is a better way to do it. With so many fields, and potentially different database sources, I don't want to go through the source and field selection process every time I generate documents.

What will happen if I create a template with the correct merge fieldnames, and then change the source database i. I'm trying to automate the process, so would really like the merge to be a simple step of taking the database information, and inserting it into templates. Thanks for any insights you can give me. Your Access document-generation function can then open whatever template is required and update whatever bookmarks, document variables or custom document properties it finds - it is a simple matter to test whether a given bookmark, document variable or custom document property exists before trying to update it.

That way, you don't need to test for their existence before updating them. Did this solve your problem? Yes No. Sorry this didn't help. Sorry, but could you explain in a little more detail what you are proposing, or provide a reference to these techniques. If I interpret you correctly, your method moves the document assembly to Access, which I percieve is less flexible than merging fields into an already formatted template in Word.

Report generation in Access doesn't appear suited to this type of task. I am unfamiliar with document variables or custom document properties.

I don't see that bookmarks are very different from inserting merge fields, with the disadvantage that they can't be seen in the document unless I am missing a step. Document variables or custom document properties store content in the document's metadata, rather than in the body of the document itself.

For some code to implement custom document properties, see:. The reason for not using mergefields in a document automation context is that you need to replace them with whatever values you're outputting, plus you have the overhead of finding the field in the document. Furthermore, you'd need multiple copies of the same mergefield wherever you want to replicate the data.

With bookmarks, you can simply input the data at the bookmarked location by referencing the bookmark's range. If you want to replicate the data, all you need to have is cross-references to the bookmarks and to ensure the bookmarked range is extended to span the new content. In any event, once the template is properly configured, you really don't need to be able to see them.Keep in touch and stay productive with Teams and Officeeven when you're working remotely. On the Page Design tab, in the Schemes group, click the More arrow on the color schemes gallery.

In the Create New Color Scheme dialog box, under Newclick the arrow next to each color that you want to change, and then select a new color. Type a name for your custom color scheme, and then click Save. All objects in your publication that were filled with scheme colors are now filled with the colors in your custom color scheme. The colors that you selected can now be used as the scheme colors when selecting colors throughout your publication.

For instance when selecting the fill color for table cells, shapes, page backgrounds or font colors. Learn more. Expand your Office skills. Get new features first. Was this information helpful?

Yes No. Any other feedback? How can we improve?

Desktop Publishing Software for Mac

Send No thanks. Thank you for your feedback! It sounds like it might be helpful to connect you to one of our Office support agents. Contact Support.In other words, it allows you to write functional reactive code in a declarative way using Swift. Functional reactive programming FRP is a special paradigm used to deal with asynchronous code.

It's a special kind of functional programmingwhere you are working with async streams of values. So basically you can process and transform values over time using functional methods like mapflatMapetc. Combine is the "native" Swift implementation of this programming paradigm, made by Apple.

swift combine create custom publisher

I already made a brief networking example of using Combinewhich is good if you're just looking for a simple code snippet to simplify your URLSession requests. Allow me to grab one example and paste it here again, I'll show you why The most important thing here is the new dataTaskPublisher method.

It creates Publisher that can send aka. Moving forward to the next few lines we can see examples of various Operator functions mapdecodereplaceErrorereaseToAnyPublisher. They are special functional methods and they always return a Publisher. By using operators you can chain a bunch of publishers together, this gives us that nice declarative syntax that I mentioned before. Functional programming is awesome! The final member of the Combine family is the Subscriber.

Since we can publish all sort of things, we can assume that on the other end of the publisher chain, there will be some sort of object that's going to use our final result. Staying with our current example, the sink method is a built-in function that can connect a publisher to a subscriber. You'll learn the other one later on I believe that Combine is a huge leap forward and everyone should learn it.

My only concern is that you can only use it if you are targeting iOS13 or above, but this will fade away in a blink with time, just like it was with collection and stack views. This is the future of aysnc programming on Apple plaftorms, and it's brighter than it was ever before. Oh, by the way you might ask the question My advice is to stay with your current favorite solution for about one year but only if you are happy with it.

You will see how amazing it is to work with this framework, so I if you are still not convinced, it's time to There are just a few built-in publishers in the Foundation framework, but I think the number will grow rapidly.

These are the ones that I used mostly to simplify my code:. Combine has built-in support for cancellation. Both the sink and the assign methods are returning an object that you can store for later and you can call the cancel method on that AnyCancellable object to stop execution. If you save the cancellable object as a stored property you can retain the subscription until you call the cancel method. Make sure you don't make extra retain cycles, so if you need self inside the sink block, always use a weak or unowned reference.

I'm not going to repeat myself here again, because I already made a complete tutorial about how to use URLSession with the Combine frameworkso please click the link if you want to learn more about it. Property Wrappers are a brand new feature available from Swift 5. Combine comes with one new wrapper called Publishedwhich can be used to attach a Publisher to a single property. If you mark the property as Publishedyou can subscribe to value changes and you can also use these variables as bindings.

In other words, the actual text of the label will be updated on the user interface. Also you only want to get updates on the main queue, since we're doing UI related stuff. You can use the receive operator for this. Creating a custom publisher is not so hard that you might think, but honestly I never had to make one for myself yet. Still there are some really nice use-cases where building a custom publisher is the right way to go. Antoine v.


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