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Our DNA is written in Objective-C
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Unwinding

You know the story: you have an app laid out as storyboard, want to show a modal view controller and when the user is done with it it you want to dismiss it, … or un-present it, or whatever you need to get rid of the modal VC and return. Now what about a view controller that can be both presented modally or via push onto a navigation controller?

Then it starts to get complicated. Unless you know about how to unwind. It’s actually quite awesome, but you have to use it several times because it is a little bit counter-intuitive how to implement unwinding. I’m writing this tutorial so that I myself can remember how to do it in the future.

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Deal of the Day

My publisher Manning  is highlighting 3 of their iOS titles on April 11, all three are the “Deal of the Day” meaning that you get 50% off with promo code “dotd041114au” if you purchase them on this day.

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New Affiliations

Manning’s affiliate system iDevAffiliate didn’t have a disaster recovery plan. So it hit them very hard – and all their clients – when their server colocation provider decided to physically move their server to a different state.

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Book Updated!

Barcodes and iOS 7

Readers of my book get good news today! My publisher Manning released version of the MEAP-version of the book.

Previously available chapters 1 through 3 have been reworked based on the feedback several reviewers gave. There were some tough requests which I just couldn’t fit into the style of the book. But for the most part the book has become much better for it.

If you haven’t pre-ordered the book via Manning’s Early Access Program (MEAP) then please do so today!

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M7 Pedometer

Apple’s iPhone 5S features a dedicated motion coprocessor, dubbed the “M7″. Probably because the M stands for Movement/Motion similar to the A in “A7″ standing for … um, Apple. This coprocessor collects and analyzes data from multiple iPhone sensors and determines two interesting pieces of information:

  • the motion activity state of its user (car, walking, running, standing still) ad hoc and history
  • the number of steps taken ad hoc and history

Let’s build a functional pedometer app so that we can learn about and explore the latter.

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Radar: AV Foundation wastes energy processing Audio even if not captured

For my book I wanted to see if there is a way to see the performance impact of various settings. So I launched the Energy Diagnostics instrument for the first time. I was not able to conclusively demonstrate the impact of any capture setting, but I did see something odd. Even though my barcode scanner sample app does not have any need for audio data AV Foundation appears to insist on capturing and processing it.

As the energy diagnostics performance instrument indicates, this causes energy usage for “Audio Processing” even though for the purpose of scanning barcodes audio is not needed. In the least developers should be able to indicate to iOS that they have no use for audio processing so that the system can conserve this energy.

This bug report is filed as rdar://16389364 and on Open Radar.

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Radar: Make Aztec and PDF417 Core Image generators public

There are 3 generators in Core Image for 2D barcodes, but only the one for creating QR codes is documented. So I filed a bug report suggesting that the documentation was “missing”. I also sent an email to the responsible Apple evangelist.

The response I got from Apple was that if something was not documented it is to be considered private. The bug report about adding the documentation for Aztec and PDF417 was closed.

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DTCoreText 1.6.11

In the 3 months since the previous release quite a few things happened on the development branch of DTCoreText. Additionally there were some issues related to iOS 7.1 and Xcode 5.1 that needed urgent addressing. Even though there are a few new features I decided to go with a bug fix version number. This way if somebody is using DTCoreText via CocoaPods and has the the version restricted to 1.6.x he gets all the critical fixes.

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DTDownload 1.1

This minor update to DTDownload adds a new feature: DTDownloadQueue now has a download priority.

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DTChartView 2.1

DTChartView is the very first component that I ever sold. Just like with the recent update to DTCalendarView there are still some stubborn users, so I finally brought it into the present.

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