Under the Bridge

Here’s a book you might think about picking up, written by Oliver Drobnik:

Barcodes with iOS 7: Bringing together the digital and physical worlds

Barcodes are a universally-accepted way to track and share information about products, applications, and businesses. Until recently, however, it’s been difficult for iOS developers to take advantage of them without licensing complicated or expensive third-party libraries. With iOS7, Apple has added all the necessary components for you to make apps that scan, display, and print barcodes.

Barcodes with iOS 7 is the first and only book that comprehensively addresses barcode technology for the iOS developer. It offers a introduction to commonly used formats, such as ISBN and UPC codes and provides real world examples that teach you how to integrate code scanning and generation into your apps. This book consolidates information about applicable Apple frameworks in one place so you can quickly add native barcode support to your existing enterprise apps or start building new apps that help bring together the physical and digital worlds…

1. Barcodes, iOS 7, and You – FREE
2. Media Capture with AV Foundation – AVAILABLE
3. Scanning Barcodes – AVAILABLE
4. Passbook, Apple’s Digital Wallet
5. Generating Barcodes
6. Getting Metadata for Barcodes
7. Putting Barcodes in Context

And you get a 1D support library for free, too:

iOS 7 does not support generation of 1D barcodes. Still I wanted to have a modern and powerful way to have this functionality present in this book which is all about all types barcodes. So you are getting the most current version of BarCodeKit completely for free. As long as you own a copy of the book in any form you can use BarCodeKit to create 1D barcodes in all your apps…

Still teetering? Buy right now for a half off deal:

Now through March 9th18th you even get 50% discount with promo code “mldrobnik”“bwiaunch50!”

So there you go, if you’ve got any interest in hooking up your apps with real world stuff, looks like a pretty darn solid investment there!

Here’s a new place to bookmark for your designer friends, or yourself should you fancy yourself a designer: Apple’s pulled together all their various design resources onto a new page

Desiging Great Apps

Exceptional user experience is a hallmark of Apple products, and a distinguishing feature of the most successful apps built for iOS and OS X. Use the resources below to learn how to build the polished, engaging, and intuitive apps that Apple customers expect…

Indeed. Don’t think there’s actually anything new there at the moment, seems to be WWDC videos and previously released documents pulled together in one place, but no doubt a good place to keep an eye on in future.

It’s also been quite a while since our last design roundup post back when iOS 7 was a polarizing novelty, so let’s see what else is new we haven’t tacked on to its updates since:

Pixel Perfect Precision Handbook 3 is out now (h/t iOS Dev Weekly), that should be on every designer’s must-read list.

This is a pretty nifty iOS 7 UI Kit Photoshop Action Set:

You’ve probably seen many iOS 7 UI Kits. But this one is slightly different, as there is no psd file involved. All you need (apart from love) is this little 1.4 MB .atn file that creates entire default look iPhone mockups for your wireframes, design mockups (use it with care) or just quick ideas…

iOS Dev Tools is an ever more comprehensively curated set of links in all categories of development interest we don’t think we’ve got around to linking to before, for design-related stuff check out these sections:

• Inspiration
• Typography
• Design
• Images and Icons

Check out all the non-design categories while you’re at it, and follow @iOSDevTools for updates!

Couple interesting posts lately about background fetch resource usage. If you’re not familiar with background fetch, that’s an iOS 7 thing that’s explained quite nicely in objc.io’s Multitasking in iOS 7 article:

Background Fetch is a kind of smart polling mechanism which works best for apps that have frequent content updates, like social networking, news, or weather apps. The system wakes up the app based on a user’s behavior, and aims to trigger background fetches in advance of the user launching the app. For example, if the user always uses an app at 1 p.m., the system learns and adapts, performing fetches ahead of usage periods. Background fetches are coalesced across apps by the device’s radio in order to reduce battery usage, and if you report that new data was not available during a fetch, iOS can adapt, using this information to avoid fetches at quiet times…

But the naîve user may find a surprise in wait:

An Unexpected Botnet

… There is, however, an intrinsic danger in applying this ability without fully thinking through the implications. When enabled within your applications you are essentially building a massively distributed botnet. Each copy of your application will be periodically awoken and sent on a mission to seek and assimilate internet content with only the OS safeguards holding it back. As your app grows in popularity this can lead to some rather significant increases in activity…

Here are the feed request frequencies for various Background Fetch enabled podcast clients … For an RSS feed that changes only once per week just these apps produce 126k web requests each week (out of 160k across all aggregators ). The feed itself is 450KB (49KB gzipped). Where it not for HTTP caching/compression (discussed later) this would be generating 56GB of almost entirely unnecessary downloads each week…

That is, indeed, a lot of almost entirely unnecessary downloads. The developers of Castro chimed in here:

The Value of Background Fetch [Point]

… Our strategy with Castro has been to employ Background Fetch to help us avoid the ongoing cost of a server. Castro polls each subscribed feed from the app regularly and posts local notifications when new episodes are found. There are pros and cons to this approach.

Pros

• We spend no time on web app development or money on server hosting. Xcode is always open.
• We have no scaling concerns.
• The continued functionality of the app is not dependent on future sales.
• There are fewer points of failure.

Cons

• Worse update performance since the app hits every individual feed, rather than one centralised server.
• A central server gives developers flexibility to fix individual feed issues, like poorly formatted dates or duplicate episodes for example…

Well, being big believers ourselves in not doing work we don’t have to, that makes a pretty compelling argument, indeed. But hark! Here’s a counterpoint from coming soon Castro competitor Overcast author Marco Arment:

The Value of Background Fetch [Counterpoint]

… Service-backed apps still have a lot of advantages and exclusive capabilities over iOS 7’s Background Fetch. I think server-side crawling is still the best choice for podcast apps and feed readers, for which users want fast updates to collections of infrequently updated feeds.

Overcast has been crawling tens of thousands of podcast feeds every few minutes for the last 6 months using standard HTTP caching headers. In the last week, 62% of all requests have returned 304 (“Not Modified”). Many of the rest returned the entire “new” feed, but none of the episodes had actually changed, making the server download and process hundreds of kilobytes unnecessarily.

An app using Background Fetch needs to make all of those fruitless requests just to get the handful of occasional changes. All of those requests cost processor time, memory, battery power, and data transfer. And each copy of the app needs to download those hundreds of wasted kilobytes when a server erroneously reports an unchanged feed as new…

A server can simply send a silent push notification to all subscribed apps when there’s new data in a feed, and each app can download just the changes. With infrequently updated feeds, like podcasts, this leads to huge savings in battery life and transferred data over time…

Well, there’s that too. So yeah, if you can’t count on decent 304 support, background fetch is not your resource-optimal choice no.

Lots of good numbers to crunch through, so read the whole posts. Personally, if the choice for your particular application is less than immediately obvious, we’d recommend implementing both methods; that way, if your service goes down, or you stop paying for it, or whatever, the app can remain functional. Safety first and second, that’s us!

UPDATES:

Apropos of things to do to avoid users calling out your app as battery-hogging, take a gander at The Ultimate Guide to Solving iOS Battery Drain

Are you reading objc.io? If not, you should be. Check out issue #9 for more than you ever realized you didn’t know about strings. Yes, strings.

Quick now: How do you correctly find the length of a string containing odd characters like emoji? And how can you be certain you’re comparing strings with combining characters for visible equivalence correctly? If the answers don’t spring to mind, check out NSString and Unicode.

How do you correctly, i.e. locale-aware, join a list of items for text display? That’s one of the many tidbits in Working with Strings.

No doubt you know how to use localized .strings … but did you know in iOS 7+ you can do locale-aware plurals with .stringdict files? And do you know how to correctly display a localized file name? See String Localization.

Need to validate your input? Or have a full expression grammar? Check out String Parsing.

Finally, know how to calculate bounding rects for attributed strings in the new non-deprecated iOS 7 way? And how to lay out hanging indents for lists and decimal-aligned number tables with Text Kit? If not, here’s String Rendering to get you up to speed.

Haven’t seen a developer periodical this consistently high quality through issue #9 since … well, ever, actually … so we strongly encourage you all to subscribe with their app to keep the goodies coming!

UPDATES:

Extending “strings” to include “text” — Open Source Library And Editor Tool For Easily Formatting Text Within Your Apps

For our Underutilized iOS Feature Of The Week award, how about UITextField/UITextView’s inputView field? Probably pretty much totally overlooked it, haven’t you? Here’s a sample implementation for next time something like that strikes your fancy (h/t: iOS Dev Weekly):

venmo / VENCalculatorInputView: Calculator keyboard used in the Venmo iOS app:

If you don’t have custom input needs but just want to improve the regular keyboard experience, there’s news for you too: Fleksy has released an iOS SDK that lets users long press to switch keyboards, if they’ve installed the free Fleksy app:

And here’s another project to improve the default keyboard:

tonqa / JustType – The Better Keyboard for iOS

JustType is a keyboard extension using swipe gestures, highlighting and suggestions. It is built to be used in any iOS text editor and all text-intensive iOS apps. And it is really easy to use. If you want to have a video demonstration you can find it on this blogpost.

And just as a side caution, if you do get all excited to implement a custom keyboard with transparency and it displays funny in iOS 7, check out this Stack Overflow question!