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Archive for the 'ipad' category

UIImage rotation, part 3

July 21, 2012 8:22 am

UIImage rotate test program

My two earlier entries on UIImage rotation are by far the most popular blog posts I’ve ever written. I’m trying to get back into the blogging habit, so here I am, exercising my weak technical writing muscles. And I’ve decided to host my code at GitHub, like all the cool kids are doing these days.

I’ve revisited my UIImage rotation code, cleaned it up a little bit, written a test program that shows various rotation effects, and put the whole thing up on GitHub.

That’s all I’ve got for now. Further bulletins as events warrant.

Installing Xcode 3 and 4 side by side on Lion

March 19, 2012 10:59 am

Xcode 4 sucks so, so, bad. It kills my productivity like whoa. As a consequence, I’ve been doing most of my work in Xcode 3 on Snow Leopard, venturing into Xcode 4 only for testing and final releases. (I am currently working on a code library that’s used by other iOS programmers, most of whom will be using Xcode 4.)

I know I’ll have to update to Xcode 4, eventually. I can’t hold back time forever. But the longer I wait, the more likely it is that Apple will fix all the glaring issues. Until then, I’m going to cling to Xcode 3 for dear life.

Recently, Apple made things a little more difficult for me by releasing a new version of Xcode 4 that only works on Lion. So I had to update my operating system, finally. But I found a way to install both Xcode 3 and Xcode 4 side by side, without any real problems.

My new Lion setup works better than Snow Leopard did in one significant respect: Xcode 3 is now able to install and debug programs on devices running iOS 5.0 and 5.1, which didn’t work for me before. I’m assuming it’s using device debugging stuff that Xcode 4 installed, but I’m not sure. I’m just glad it works, because I use it a lot.

Here’s the steps I took, which might work for you as well.

Step 0: Remove all existing Xcode versions

I’m assuming you are starting from a fresh install of Lion, which doesn’t contain any developer tools at all. If not, the instructions given here probably won’t work. The order of installation is important.

This command should work to uninstall Xcode 3:

sudo /Developer/Library/uninstall-devtools –mode=all

And this one will uninstall Xcode 4:

sudo /Library/Developer/Shared/uninstall-devtools –mode=all

… then remove Xcode.app from your /Applications folder.

Step 1: Install Xcode 3.2.6

As of this writing, the most recent version of Xcode 3 is still available from Apple’s developer site. Download Xcode 3.2.6, which will require you to log in with your Apple dev credentials.

Alas, Xcode 3 doesn’t really want to be installed on Lion. No matter, its version checks can be defeated. I found out how to make it work from this link. I’ll repeat the instructions here, in case that link goes dead:

1. Mount the Xcode 3.2.6 DMG
2. Open Terminal
3. Enter these commands:

open "/Volumes/Xcode and iOS SDK/Xcode and iOS SDK.mpkg"

… then run the installation program as usual.

Partway through, the Xcode 3 installer demanded that I shut down iTunes, even though it wasn’t running. On a hunch, I used Activity Monitor to kill iTunes Helper, and that did indeed make it shut up and finish installing.

If you want to create a link to Xcode 3, the app is installed here by default:


Drag it from that location into the Dock or wherever else you’d like it to be.

After Xcode 3 is installed, you’ll want to launch it to make sure it really works. On my system, Lion declared that it needed to download a Java runtime before this was possible.

Step 2: Install Xcode 4.3.1

Apple has decided to move Xcode 4 into the Mac App Store, so you’ll have to run the App Store app to download it. It doesn’t have an installer like earlier Xcode versions, it’s just a plain old app in your /Applications folder. Start it, and it will declare that it has to install a framework first, so let it do that.

At this point, you’ve got a cosmetic problem: the Xcode 3 and Xcode 4 icons are identical. You can solve that problem by installing Jeff LaMarche’s replacement icon. He wrote that article for a much older version of Xcode 4, but the replacement worked just fine for me.

Step 3: Install the command line tools

Xcode 4 no longer installs command-line tools by default. Assuming you need them, like I do, then you should open the Xcode 4 preferences window, go to the Downloads tab, look for the item labeled “Command Line Tools,” and press the Install button. This will take just a few minutes, and the tools will be installed, inside the Xcode 4 application bundle.

The next problem you’ll discover is that, if you fire up a terminal window and type a command such as xcodebuild, you’ll get the Xcode 3 command line tools by default. That is not what I want. So the next step is to modify your .profile file, or whatever you normally use to control the PATH environment variable, and add these paths near the beginning:


Step 4: Device debugging

If you’re like me, you have a pile of devices you use for testing and debugging. Both Xcode 4 and Xcode 3 are able to install and debug apps on all my devices, which are running versions of iOS from 3.1 to 5.1.

The trick is to start on Xcode 4. Connect your device to the 30-pin connector, open Xcode 4, and look in the Organizer window. If this is the first time you’ve connected this device, it will ask you if you want to use it for debugging, and it may have to download some files to make that possible. Eventually, the little LED next to the device should turn green. After that, exit Xcode 4, open Xcode 3, and try it there. It looks like Xcode 3 copies some files from wherever Xcode 4 stashed them, and then it’s off to the races.


I’ve been using this setup for a number of months now. What I’ve discovered is that Xcode 3 is unfortunately pretty crippled when run on Lion. Debugging via GDB is impossible. Source code windows often have bogus titles applied. Various other cosmetic bugs abound. In short, Xcode 3 is not nearly as pleasant to use as it was on Snow Leopard. But it’s still better than Xcode 4, for the most part, in my opinion. So I soldier on.

And … fin

As of this writing, it is now a few months later, and I use Xcode 4 all the time. I still don’t like it, but there are way too many things that Xcode 3 can’t do anymore, and switching back and forth all the time is giving me a headache.

I did save the Xcode 3 versions of Pixie and Property List Editor, however. You can download a more recent version of Pixie from Apple’s developer site, but it’s not as good as the old one, and the icon is uglier. With Xcode 4, you’re expected to edit property lists within the IDE itself, but that’s often not very convenient. If you’re going to follow my lead, be aware that Property List Editor won’t work without PlistEdit.framework, which is installed in your /Developer folder along with all the other Xcode 3 stuff.

And with that, I am officially giving up the fight. You win, Apple. I sure wish Steve J. had been forced to use Xcode as much as I do. I bet it wouldn’t have turned out like this.

UIButton graphics highlighting

January 31, 2011 6:54 am

I have often tried to create a UIButton subclass to do something special, like draw a shadow, but couldn’t make it work. You can’t just override UIView’s drawRect: method and get the results you expect. My usual response to that is: Fine, I’ll make my button a subclass of UIControl, then.

That leaves the problem of how to highlight the button’s image when it is pressed. UIButton does a great job of this, drawing a black mask on top of the button’s image, ignoring any transparent pixels. I’ve been trying to figure out how to reproduce that effect for probably a year, I suspect, without success.

CoreGraphics is powerful. There’s pretty much nothing it can’t do. But it’s not exactly easy to work with. I have finally read enough of other people’s blog posts so that I can cobble together a solution. I’ve included a function below that inputs a UIImage object and outputs a new UIImage with a black mask drawn over it, exactly the same effect that UIButton uses.

UIButton highlighting

I’ve included a screen-shot from the simulator to show what the effect looks like. On the left, you’ll see an image that is similar to the icon for the Calendar program on the iPhone. Next is that same image, highlighted by UIButton. The third image is highlighted with the function shown below. The two highlighted versions are almost exactly the same. You can tell the difference with a color-dropper tool, but I doubt you could tell them apart with the naked eye.

I know I pretty much never use code from other people’s blog posts without modifying it to suit my own uses. Assuming you’re like that as well, here’s some notes that will help you understand the code better.

The alpha value for the black mask, 0.46, was chosen because it produces results nearly identical to what UIButton does. You can make that number bigger or smaller for a lighter or darker mask.

UIGraphicsBeginImageContextWithOptions() is the best function to use to begin an image context. It will get you high-resolution graphics on the iPhone 4’s “retina display.” But that function does not exist on older versions of iOS. Therefore, we test for its existence before calling it, by checking to see if its function pointer is NULL. If so, we fall back to the older method that’s been available since the earliest iOS versions. If you don’t plan to support versions of iOS earlier than 4.0, then you can omit the availability test.

There are a couple of lines of code that transform the coordinates normally used by CoreGraphics functions to those normally used by UIKit objects. Without those two lines, the black mask would be drawn upside-down. I don’t understand this business very well. I just know the function fails without them.

The secret sauce is CGContextClipToMask(). It was easy to figure out how to draw a colored mask over an existing image, but you need this extra step to prevent the mask from being drawn over transparent pixels.

UIImage* WBHighlightImage(UIImage* image) {     const CGSize  size = image.size;     const CGRect  bnds = CGRectMake(0.0, 0.0, size.width, size.height);     UIColor*      colr = nil;     UIImage*      copy = nil;     CGContextRef  ctxt = NULL;         // this is the mask color     colr = [[[UIColor alloc] initWithWhite:0 alpha:0.46] autorelease];     // begin image context     if (UIGraphicsBeginImageContextWithOptions == NULL)     {         UIGraphicsBeginImageContext(bnds.size);     }     else     {         UIGraphicsBeginImageContextWithOptions(bnds.size, FALSE, 0.0);     }     ctxt = UIGraphicsGetCurrentContext();         // transform CG* coords to UI* coords     CGContextTranslateCTM(ctxt, 0.0, bnds.size.height);     CGContextScaleCTM(ctxt, 1.0, -1.0);     // draw original image     CGContextDrawImage(ctxt, bnds, image.CGImage);         // draw highlight overlay     CGContextClipToMask(ctxt, bnds, image.CGImage);     CGContextSetFillColorWithColor(ctxt, colr.CGColor);     CGContextFillRect(ctxt, bnds);     // finish image context     copy = UIGraphicsGetImageFromCurrentImageContext();     UIGraphicsEndImageContext();         return copy; }

iPhone and iPad SDK coexistence

February 14, 2010 7:14 am

Apple has released a new SDK specifically for iPad. It’s not yet ready for prime-time, so if you want to continue to develop for iPhone, you’ll need to use both the old and new SDKs for awhile. Curious about the logistics of this endeavor, I googled up this article. I dutifully followed the instructions and installed the beta 1 release in a separate dev directory. Yeah, I’m calling shenanigans. It did not work. I think it’s a bit irresponsible to post something like that without having tried it.

You can’t completely separate the two SDKs. According to the release notes, the one that is installed last is the one whose compilers will be used for both. I had other problems as well. Both the old and new device simulators were crashy. So I completely wiped both sets of dev tools and reinstalled the iPhone SDK.

Recently, Apple released beta 2 of the iPad SDK. They may have fixed the problems I experienced before, but I’m not taking any more chances. This time, I got myself an external Firewire hard drive. USB 2.0 would also work, but I prefer Firewire for a possibly frivolous reason: I have so many USB devices that it’s difficult to find a place to plug in a new one, but I have two Firewire ports on the back of my Cinema Display that are otherwise unused.

This next part is important. You’re going to need to boot off this drive, so its partition map scheme must be set to “GUID Partition Table.” If it isn’t, you should reinitialize it so that it is. On the Mac, you use the Disk Utility program for this. It doesn’t create GUID partition tables by default, so you have to press the button that says “Options…” and change it.

Next, use a program like Carbon Copy Cloner to make a copy of your primary hard drive onto the external drive. Finally, in System Preferences, pick “Startup Disk,” select your external hard drive, and reboot. Now install the new iPad SDK. It will be copied onto your external disk, leaving your primary disk alone. This way, the two SDKs won’t butt heads with each other.

It’s a shame that Apple is making us solve a software problem with hardware, but this is the sort of inconvenience you have to put up with if you want to live on the bleeding edge. I can’t even remember the last time I had to use the Startup Disk pref pane before this. It’s been years, surely. This reminds me of when I used to work at Be, and we had a new version of BeOS to install every couple of weeks.