Facebook’s London Mobile Forum 2.0

Scott Goodson of Facebook starting the discussions with developers

Scott Goodson of Facebook starting the discussions with developers in Hoxton, Shoreditch, London.

Last week I was fortunate to attend Facebook’s London Mobile Forum 2.0. This gathering of top London mobile developers and designers was a great chance to swap ideas and listen to a number of talks by Facebook, Big Nerd Ranch, Yammer, Bloom and Mozilla to name a few. The event was tiny with only 60 people in the room but it had many big players and it was great to talk to as many of them as possible, particularly at the free bar Facebook had laid on in the evening! So what mobile development secrets did we talk about? Continue reading

5 Time-saving Objective-C tips every developer should know

Batman Flat White Coffee Here’s a quick fire list of 5 time-saving Objective-C tips that every developer should know. Perfect for making time for that extra coffee!

1. Enum shorthand

Enums at their simplest are labelled sets of integers. Where an inexperienced programmer might use a number to represent the download state of an image lets say, e.g. 0 = queued, 1 = downloading, 2 = downloaded, 3 = complete… When using these numbers in actual code a simple slip of the finger on the keyboard and they could easily type an extra digit in their if statement or assignment. These types of errors don’t usually show up when compiling. Even worse, these are usually obscure errors that only reveal themselves at run-time and only then when things don’t work as expected often requiring considerable debugging effort.

This is where enums step in. Enums are really handy and allow you to associate symbols or ‘labels’ with integers. If you type an enum value that doesn’t exist the compiler steps in and reports an error at compile-time instead and Xcode will probably suggest a fix for you if it was a typo! The other benefit of enums is that you can quickly add new values into them and assuming your code doesn’t save the integer to disk your code will automatically work with the new values.

There are a couple of different ways to define enums but the easiest way which will also provide Xcode with some extra compiling hints is as follows:
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Core Animation stops animation on app relaunch

On one of my projects I discovered a bug in a never-ending animation I had set up. Whenever the app was suspended (such as when you multitask and open another app), on relaunching the app the animation was frozen. After some investigating, I discovered that with Core Animation you need to set a flag on the CABasicAnimation class called removedOnCompletion to NO otherwise the animation will get cleaned up when it gets suspended.

Does this seem like a bug or a feature?

Custom fonts on iPad and iPhone

Just incase you didn’t realise, with iOS 3.2 (iPad) and above you can load in custom fonts and use them with a standard UIFont object. There are a few catches… The font must be in the following format: –

  • OpenType Format (OTF)
  • TrueType Format (TTF)

Once you’ve dragged your chosen font file into an Xcode project, the next step is to add a line into the application’s Info.plist file. Add a new key UIAppFonts and make it an array. Expand the array and add a new string for each font, making the string the file’s full name including an extension.

Xcode Screenshot

You’re all set up now to use the font. That would be great if you knew which font it was! Here is a great little snippet for looping through all the fonts loaded into the system. Scan through the list and find your font.

To use your font now, just use the standard UIFont constructor…

Some points to note: –

  • You can also use the font inside UIWebViews.
  • Interface Builder for XCode 3.2 has a bug that won’t let you choose the font. You have to do it in code.
  • Loading in too many fonts will slow your loading time down and will hurt your users’ eyes.