Prototyping in a testbed
Video: Prototyping in a testbedSometimes in the course of your work as a programmer you need to try a snippet of code or test out an idea or even write a simple test suite for a class or a library that you're writing. For these situations it can be helpful to have a small, simple, flexible base of code to use as a test bed to test your ideas in. Here we have such a test bed, and I call it Testbed, and you'll notice if I run this in the simulator it displays some messages up on a text view here on this iOS Device.
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The iOS software development kit (SDK) includes the popular SQLite library, a lightweight yet powerful relational database engine that is easily embedded into an application. In this course, Bill Weinman teaches you how to build an RSS reader for iOS devices, integrating XML data and a streamlined interface. He explains how to use the SQLite database, display information in a table view, code view controllers, and create a preferences pane for your app. The resulting application is optimized for all iPhone and iPad displays.
- Prototyping the app
- Coding and working with a testbed
- Creating an Objective-C interface for SQLite
- Designing a database schema
- Creating the view controllers
- Reading and writing to the database
- Parsing the RSS feed with NSXMLParser
- Updating the item view with feed items
- Implementing the pull to refresh gesture for iOS 6
- Creating a universal application with multiple views
Prototyping in a testbed
Sometimes in the course of your work as a programmer you need to try a snippet of code or test out an idea or even write a simple test suite for a class or a library that you're writing. For these situations it can be helpful to have a small, simple, flexible base of code to use as a test bed to test your ideas in. Here we have such a test bed, and I call it Testbed, and you'll notice if I run this in the simulator it displays some messages up on a text view here on this iOS Device.
If we look at the code here I have a simple runTest function that puts out messages using this message function, Testbed version and for id in this array I have a little message that says object is with the string for each member of the array and right here we have Testbed Version 1.0, object is Klaatu, barada, nikto, and that's exactly what we have there. So you can see that this is very simple to test code in. Now, you could leave the stimulator alone, and you could use NSLog, and that's okay, and many people do that--and you can certainly do that if you want to--but it's nice to have the log for errors and the stimulator screen is a lot less cluttered, and it's easy to read this way.
So, this Testbed is easy to build and in fact I've already done a lot of the work for you, so let's take a moment out from our busy day and build a little Testbed to experiment and learn with.
Find answers to the most frequently asked questions about iOS SDK and SQLite: Building Data-Driven Apps (2013) .
Here are the FAQs that matched your search "" :
- Q: Why is the RSSDB library in the exercise files different than the one in the videos?
A: The RSSDB library had to be updated to work around a bug in the iOS 7 SDK.
There is a bug in the iOS 7 SDK that prevents the BWDB fast enumeration implementation from working on a device. The symptom is code that runs fine on the emulator, but not on a device. iOS devices use an ARM processor, while the emulator runs on your Mac's Intel processor. This points to the LLVM ARM code generator as the source of the bug. Because the bug appears to be in the LLVM compiler, it may be some time before it is fixed.
As a workaround we have changed the getFeedIDs and getItemIDs methods in the RSSDB library so they don't use Objective C fast enumeration.
Please note that this same bug also affects some of the BWDB testbed code in Chapter 2. The result is that it will run on the emulator but not on a device.
- Q: After upgrading to Xcode 5.1 I get an error that says:
"Used type va_list (aka_builtin_va_list) where arithmetic or pointer type is required"
- A: Please download the exercise files again to get the latest version of the BWDB library.
- Q: I'm using Xcode 6. Why am I getting error messages with the exercise files?
- A: A lot has changed in iOS since this course was released. The author is in the process of rewriting the code and updating the course for iOS 8. In the meantime he has prepared a version of the app that works in iOS 8 and Xcode 6. Download it here:http://ios.bw.org/
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