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One of the big mysteries of CoreAnimations are 3D transforms. You might have seen them used in popular apps like Flipboard (page turn) but there are hardly any good tutorials in how they actually work. In fact, you find only one from 2008 what was written when OS X Leopard was still around. I blame that there are several things that are counterintuitive about using 3D transforms and perspective wi

It happens to the best: you add new features to an app localized in several languages. You are not the lazy type that names the NSLocalizedString key’s the same as the English-language strings. Instead you name the keys semantically, like DOWNLOAD_ALERT_MSG. Then when it comes to shipping you send the client a note that there are some new strings and assume that he will be able to find out which a

When you start using CoreData for persisting your app data you start out with a single managed object context (MOC). This is how the templates in Xcode are set up if you put a checkmark next to “Use Core Data”. Using CoreData in conjunction with NSFetchedResultsController greatly simplifies dealing with any sort of list of items which you would display in a table view. There are two scenarios wher

My partners at BytePoets have been causing their keyboards to emit steam from walking through 26 issues that we identified on the 1.0 release just 9 days ago. Almost all had been identified as typical “oh shoot” elements, mostly items that you only find when people begin to actually use your software. Also I was able to smuggle in one or the other new feature since I consider “user confusion” also

Honestly I was very much excited when I found that I can use my current knowledge of Objective-C and Foundation classes like NSString to also build nifty little tools. Previously I had to resort to bash script to perform one-off operations on files that where too tedious to do manually. But knowing what I am going to show you in this article will enable you to also write these littler helpers. I b

A very interesting yet very undocumented functionality of Xcode is that you can have sub-projects in your project tree. You can add an xcodeproj to your project and link to this project’s output. This is exceptionally useful if you are developing some functionality in a contained project and now want to access this polished functionality from another project. Like for example you want to add to yo

Apple sends a clear message to us developers: “Stop supporting 3.x”. They say that most loudly by omitting Simulator 3.2 from Xcode 4.1 which I painfully noticed when I wanted to debug a 3.2 bug in a component of mine. I had updated everything to Lion and installed Xcode 4.1 because that’s the first version supporting Lion. So if you are basing your operations on the most current “stable” versions

Back in April Oliver wrote an excellent article entitled “Making Your Own iPhone Frameworks”, in which he explained how to do what many developers still proclaim as impossible: how to create custom frameworks that you can use in your iPhone apps! I would recommend that you read Oliver’s article first, especially if you’re wondering what a framework is… or, possibly, why you should consider making

Before the iPad was released you had basically two ways how to get text on screen. Either you would stick with UILabel or UITextView provided by UIKit or if you felt hard-core you would draw the text yourself on the Quartz level incurring all the headaches induced by having to mentally switch between Objective-C and C API functions. As of iOS 3.2 we gained a third alternative in Core Text promisin

Peter Reinhardt asks: The app AppSwitch displays the console entries from NSLog logging in the iphone app. I tried to figure out how they do it but couldnt find an API. Do you have an idea? Intriguing question! My first gut reaction was that the guys from AppSwitch must have some magic sauce as I didn’t know of a way to access the console log on device like the Xcode organizer is able to. My first

Communicating with web services you have to decide on a way to transport the date back and forth. Recently – with the help of the popular Twitter-API – JSON seems to have come ahead in the race. Other contenders are property lists and XML. Property Lists (PLISTs) are available in XML-Text and a binary (“old”) format and are widely supported in the Apple APIs which makes them a joy to work with. JS

Almost always when we iOS developers want to display some rich text we are using UIWebView. That’s not by choice, since traditionally Apple did not provide any classes to us being able to show formatted text. That changed slightly with the iPad, because in 3.2 we got CoreText as well as CATextLayer. CoreText gives us NSAttributedString which is basically a string that can have different attributes

UPDATE: Added handleOpenURL to the flow charts. Added UIApplicationExitsOnSuspend. Untangled some lines. UPDATE: renamed deprecated handleOpenURL to newer name. Now that we all are moving our source code gradually to iOS 4 I had to pause and think a bit about where to move which code. A problem that I’m facing frequently when updating a project is that the didFinishLaunching is only called if the

Have you ever really TRULY looked at the documentation of UIFont? I had to, because I was looking for some metrics information that I could use to custom draw UILabels. And if you want to be independent of what font is set, then you have to get certain metrics, but the Apple SDK documentation of UIFont leaves a bit to desire. When I asked which characters would be good representatives of a font, I