In your iPhone/iPad apps you often need to know how many times your user tapped in a view. This can be challenging because, though the user may have tapped twice, you will receive the event and it will look like they tapped once as well as twice. If the user triple-tapped, you will get the event for one tap, two taps, and three taps. It can get a little frustrating, but the trick is timing. You simply have to wait a period of time to see if another tap comes. If it does, you cancel the action spawned by the first tap. If it doesn’t you allow the action to run. There’s a few little nuances to getting it to work, but it can be done. Here is how.
So Marcus is the Core Data guy, but I’ve been working with it a good bit myself lately and was recently faced with having to add re-ordering for a list of entities in a UITableView. The methods I found online for accomplishing this all suggested using an NSMutableArray as the data source for the table view. That will work, but I came up with another method, though similar, that achieved what I need without having to switch from using my NSFetchedResultsController as the data source behind the UITableView. In the end, I did use an NSMutableArray, however, I end up using it just to take advantage of its indexing. Read on to see what I mean.
The default implementation of the UISplitViewController based template in Xcode does not provide a navigation controller stack in the detail view. Instead it is just a regular old view with a navigation bar at the top. I suppose there are cases when you might want such an implementation, however, i think you would more commonly want there to be a navigation stack for cases when you wan to push new view controllers for your users to see. In this post i intend to demonstrate how to convert the default template to something more useable.
Everything is moving toward the cloud and unless you’re building calculators, unit converters, or miniature golf score keepers your iPhone app needs to know how to get data from it. In this blog post I intend to demonstrate how to set up a simple server application and how to retrieve data from it and post data to it using Cocoa Touch. I have chosen to use PHP on the server side because of it’s simplicity and ubiquity, and because I’ve know it, somewhat. You should, however, be able to implement something similar using your server side language of choice.
In many cases when you go to access remote data, you do so through a web service API. While services based on such technologies as SOAP or XML-RPC are standards that provide reasonable methods for retrieving and updating data, REST seems to be the methodology gaining the most ground lately. For our purpose in this post I won’t get into great detail of how to implement a REST base web service as, again, REST is not a specific implementation but rather a methodology. (Read up on it elsewhere if you don’t understand what this means). However, I will talk about it briefly so that you can get on the right path for doing your own REST implementation.
I had to post a link to this one as well as Fraser does such a great job explaining why the iPad is so compelling . From Fraser’s post:
The tech industry will be in paroxysms of future shock for some time to come. Many will cling to their January-26th notions of what it takes to get “real work” done; cling to the idea that the computer-based part of it is the “real work.”
It’s not. The Real Work is not formatting the margins, installing the printer driver, uploading the document, finishing the PowerPoint slides, running the software update or reinstalling the OS.
The Real Work is teaching the child, healing the patient, selling the house, logging the road defects, fixing the car at the roadside, capturing the table’s order, designing the house and organizing the party.
Exactly! The iPad is genius and it will revolutionize not just books, magazines, etc., but it will revolutionize computing as we know it. I don’t know about you, but I’ve got the new SDK fired up and ready to start rocking some apps and it is a very exciting new platform!
Upon first glance, the UIButton class doesn’t seem to provide what you might expect in terms of customization. This often causes developers to resort to creating buttons in an image editor and then specifying that in the Background field in Interface Builder. This is a fine solution and will likely give you what you need, but with Core Animation layers there is a simpler way to achieve the look you want without having to create an image. This post will demonstrate how.
Our Core Animation book should be available by the end of the year. Go ahead and pre-order it now at Amazon if you would like ;-). When we started writing for Addison-Wesley back in September of 2008, I had no idea how long to expect it to take to finish a technical book as this was my first. One thing I discovered though, is that it is when you are about ready to go to production you start to realize all of the things that you probably should have added to the book, but didn’t think of in time. This blog post will cover one such item as a way to make up for not thinking of it in time. I may include this in a second edition if there is one, but consider this one a freebie. (more…)
At first glance setting a height dynamically for table view cells seems a little daunting and the first most obvious answers that come to mind are not necessarily correct. In this post I will show you how to set your table view cell heights dynamically based upon the text content without subclassing UITableViewCell. You can subclass it, however, doing so does not make the code much cleaner as setting the height is done in your delegate for the table view itself rather than the cell anyhow. Read on to see what you need to know to make dynamic cell height sizing a breeze.
I’ve seen a good bit of sample code that shows how to implement using a UINavigationController in a view controller that is managed by a UITabBarController, but I haven’t seen much on how to do it with Interface Builder. Turns out that it’s pretty simple and I’m going to show you how.
Update: This is documented behavior.
Every now and again while doing development you stumble upon something that makes you go, hmmmm. Those are normally the moments at which you have to ask yourself, “is this a bug or a feature”. If it’s a bug, then you should file a radar with Apple, however, what if it’s a feature? You blog about it, of course!
I have done a bit less iPhone development than Marcus, so he was a little stumped while looking through some of my code where I created a view controller using a simple alloc/init. Most interestingly is that fact that the app works. It loads the correct nib and displays the view just fine without any trouble. Notice I said alloc/init and not alloc/initWithNibName. How can this possibly work? How did my controller “know” which view to use?
Every once in a while I find a way to combine multiple technologies that, while they don’t produce anything terribly useful, are very interesting when combined. In this post I will be taking a look at combining Core Animation and QuickTime. As you may or may not be aware, you can draw in a graphics context while your Core Animation animation is running and add each image created to a QTMovie object from QTKit. This enables you to create a QuickTime movie of your Core Animation animation. Here’s how.
As you develop applications for the iPhone, you will likely use the project templates provided in Xcode. One such template, called “Tab Bar Application” helps you get a tab bar application set up quickly, but by default the application it generates only supports portrait mode for display. So how can you make the application also support landscape or even only support landscape? In this post we will address that question.
Starting and stopping animations in Core Animation is as simple as adding and removing your animation from the layer upon which is being run. In this post I am going to talk about how to interrupt animation progress and how to determine whether an animation completed its full run or was interrupted. This is accomplished with the animation delegate -animationDidStop:finished.
A lot of hard work has gone into this book already and I see it becoming the definitive text on the subject of Core Data. The release date is slated for March 30, 2009, but it’s great to see it in beta. If you want to pick up the beta in PDF, it is available now from Pragmatic here: Core Data: Apple’s API for Persisting Data under Mac OS X.
While new Cocoa programmers will find it a great help to getting started quickly with Core Data, the book also covers some really interesting and advanced topics such as data versioning and migration, Spotlight/Quick Look integration, Sync Services, and multi-threading. You can really see Marcus’ command of the subject shine in these chapters which are already available in the beta.
Give Marcus some feedback on the book as it progresses. It’s going to be a great reference for any Cocoa Developer looking to harness the power of Core Data.
$21.00 for the beta PDF
$41.35 for the beta PDF plus hard copy when it’s released in March.
Mad props to Marcus. Congratulations!
It is often helpful to create a custom control for you application that will display a value as a level like a gas gauge shows how full your tank is. In this post I will demonstrate how to create a three layer tree that will show the current rotation of a circular layer as the value from a slider (NSSlider) is updated in real time. The layers include the root layer, the rotation layer, and a text layer that will display the current rotation in degrees.