the great uitableview race

For the iTunes U course on iOS programming I followed along with the homework assignments. The last assignment was a Flickr app that shows photos at popular geotagged locations. I had an issue with UITableViewCell reuse and background threads populating the thumbnail image that I thought was worth sharing. On iOS in order to improve performance some of the different libraries like UIKit and MapKit have the ability to reuse UI elements once they are no longer on screen. When reuse occurs it is up to the developer to provide new data for the UI element. My problem was that two or more asynchronous operations could change the same table cell. One solution would be to stop reusing table cells but that is not ideal. As long as I can identify which image should be shown in the cell at a given time I can make sure the correct asynchronous operation updates the cell. Since UITableViewCell derives from UIView it has the tag property which is a NSInteger. The UITableView represents an array of data from Flickr. Before making the asynchronous call I set the cell’s tag to the index in that array it currently represents. Then in the callback function I only update the cell if its tag matches the index for which the asynchronous call was made. Without this change in place it is possible to scroll through the list rapidly and see the thumbnail change two or three times for a cell while the remaining thumbnail downloads finish. But the last update could be the wrong thumbnail. The code itself is simple and can be found here: https://gist.github.com/803766.

silly apple ui

I have been working my way through the Stanford iOS programming course. It’s been my biggest exposure to the Apple developer ecosystem. So far I have encountered three user interface components in the tooling that I trip me up. The first is Interface Builder (IB). This tool is separate from the XCode IDE. I typically forget to save changes. In my mind XCode and IB are one and so I expect my changes to be saved when I build. I usually end up with a blank screen and then I remember: save in IB! In XCode 4 IB is supposed to be integrated so hopefully this issue is fixed. On the code side of things all the UI pointers are nil. In Objective C it is perfectly valid to send messages to those nil objects. Personally, I would like to fail fast and have the program crash as I think that would help me find the root cause quicker. Second, when opening older projects I often get the “Base SDK is missing” error. It’s easy to change in the project’s build settings but after the change it seems you must reload the project in XCode. It wasn’t entirely obvious at first but restarting an application usually fixes everything regardless of the platform. Finally, I wanted to see how my custom drawRect: code was visually different on the retina display versus the old display. I checked out an older device from work and took it too my office and tried to provision only to receive this error message:

Only one developer gets to register a device I figured. I searched the internet a bit and finally decided I would just provision the device as a tester’s device. While I was looking for the page to do that I found my device list had two devices listed. That was odd because I only expected to see my iPod listed. I looked at the second device and sure enough it had the same ID number as the device I had checked out. The dialog meant to add devices didn’t tell me it had done this. It only displayed an error message asking for another ID number. Overall the tooling is pretty good and it does not get in the way that often.

facebook ads

If Facebook ads are any indicator of the health of the economy then it must be great. For the past 2-3 months I have noticed an increase in the number of job ads. I think the cause might be one or a combination of the following:

• More employers are using Facebook to advertise open positions which could mean the economy is doing better. Yay!
• I switched jobs from a Visual Studio SDET to Bing Mobile SDE back in October. The “developer” label probably draws more employer attention than the “tester” label.
• The Microsoft keyword in my profile certainly helps. It’s like going to a big name school. Society assumes it must be good. In the big scheme of things it’s pretty silly to base potential success off of that attribute alone.

Here are some of the job ads I have seen so far:

• imdb.com
• logos.com
• Various social game sites like wooga.com and zynga.com
• palantir.com
• inrix.com
• marchex.com - they advertise using the domain makehistory.com which appears to be their informational recruiting site.

It’s not uncommon for 2 or 3 of these to show up on any given Facebook page. The Marchex ad always catches my eye. Their tag line reads: “Tired of Reorgs.” Which probably catches the attention of most Microsoft employees. I think ads on Facebook are going to start to look more and more like this though. They will continue to get more personal in nature. I know I click on more Facebook ads than Google ads. When something is so relavent it sparks my curiosity. I don’t know that Facebook will take away Google’s AdWord revenue but I think they are in a pretty good position to compete for AdSense revenue. IMDB.com also advertises positions on Facebook. They didn’t take the “reorg” approach but went with the commute. The 520 bridge which connects Seattle to Microsoft can get backed up. Personally, I am not “tired of the bridge” as their ad said since I don’t live in Seattle. Their ad was clever but not clever enough to take my address into account. Finally, the last ad that caught my eye had the tag line: “Stressed At Microsoft?” The ad was for counseling services at eastsidecounseling.org. Between the competitor’s job ads and counseling ads a cynic might say Microsoft isn’t the place to work. I wonder what kind of targeted ads I would see if I worked at Google, Amazon, Facebook or Apple? For Amazon I am guessing “Tired of the Pager” would make a pretty catchy tag line. I am sure the others have quirks their competitors use to attract talent but I don’t know enough about those companies to venture a guess.