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Posts tagged ‘Apple’

18
Dec

Take Me Home

Take Me Home was a good “Hello, World!” iOS app, but its time has come. I’ve pulled Take Me Home from the App Store. Goodnight, sweet prince.

16
Nov

Selling “Physical Goods” or “Goods and Services Used Outside of the Application” in an iOS app

Since this question has come up a few times, I thought I’d record my answer to a common question:

Can I use an iPhone app to sell something outside of the App Store?

Reading Apple’s rules for the App Store makes developers nervous. We’re walking on eggshells, hoping that our application will not run afoul of the myriad of regulations put forth by Apple for inclusion into the store. So, questions like this come up. I’ll reproduce my answer here:

Obviously, I am not a lawyer, but I think you’ll be OK. Here’s my interpretation of the three relevant rules from the developer guidelines (emphasis mine):

11.1 Apps that unlock or enable additional features or functionality with mechanisms other than the App Store will be rejected.

11.2 Apps utilizing a system other than the In App Purchase API (IAP) to purchase content, functionality, or services in an app will be rejected.

11.3 Apps using IAP to purchase physical goods or goods and services used outside of the application will be rejected.

The first rule prohibits you from unlocking anything inside of your app with something other than the App Store. This would prevent you from, say, making a game that downloads new levels from your server based on your membership to a website.

The second rule prohibits you from, say, making a game and enabling PayPal in it to unlock more levels. Apple wants you to use in-app purchase for that.

The third rule—and this is where it gets interesting—prohibits you from using in-app purchase in an application to buy “physical goods” or “goods and services used outside of the application.” Nowhere does it say, however, that you can’t use other purchasing systems.

With that third rule, I think what Apple is saying is this: anything that runs on the iPhone must be purchased through the App Store, and everything purchased in the App Store must run on iOS. For something like insurance, which isn’t new functionality in the app, I think you’ll be OK. This is absolutely worth an e-mail to Apple’s technical support staff, but if you look at Amazon’s app, you can purchase physical goods using Amazon’s checkout system.

I’d love to be proven right or wrong on this. If my reading is correct, then using an iOS app as a storefront is perfectly acceptable. If I’m reading this too charitably, then you’re better off making this type of application for a different platform.

16
Nov

Autorelease is Not Your Friend

How many times have you written this line?

NSMutableArray *foo = [[[NSMutableArray alloc] init] autorelease];

At first glance, it looks fine. foo is an autoreleased NSMutableArray that you can use and, at the end of the method, it’s gone into the ether of the autorelease pool. Don’t get me wrong, most of the time, this use of -autorelease is acceptable. But, in this post, I’ll try to convince you to use autorelease differently in subtle ways. Read moreRead more

19
Aug

Apple Doesn’t Like “Die, You Gravy-Sucking Pig-Dog!”

There’s a relatively well-known Easter egg in BSD’s shutdown.c: a function named die_you_gravy_sucking_pig_dog (side note: I’ve got three-to-one odds that say whoever wrote that has a huge UNIX beard). It turns out that Apple doesn’t care to have such uncouth function names floating around, so they re-defined it:

#ifdef __APPLE__
void log_and_exec_reboot_or_halt(void);
#else
void die_you_gravy_sucking_pig_dog(void);
#endif

Sure, it does the same thing, but I don’t think log_and_exec_reboot_or_halt has the same panache.

20
Jul

Xcode 3.2: Using GDB as a Non-Admin User

New in Xcode 3.2 is an authorization setting that looks like this:

<dict>
	<key>allow-root</key>
	<false/>
	<key>class</key>
	<string>rule</string>
	<key>comment</key>
	<string>For use by Apple.  WARNING: administrators are advised not to
	        modify this right.</string>
	<key>k-of-n</key>
	<integer>1</integer>
	<key>rule</key>
	<array>
		<string>is-admin</string>
		<string>is-developer</string>
		<string>authenticate-developer</string>
	</array>
	<key>shared</key>
	<true/>
</dict>

The upshot of this is that if you aren’t in the _developer group in the local directory, you’ll have to authenticate as an administrator to use gdb or some of the performance tools. For the vast majority of developers on Mac OS X, who run as an administrator, this is fine, but if you’re running as a regular user, either for security reasons or because you’re in something like a lab setting, this can be a problem. To add a user to the _developer group, use the dscl command:

dscl . -append /Groups/_developer GroupMembership UserName

Replace UserName with the short name of your user account (or $(whoami)) and you should be all set.

If you’re administering Mac OS X in a lab setting, you can either create a LaunchAgent that handles this or a login hook. See the Apple tech note “Running At Login” for more information on login hooks. As an added touch, my login and logout scripts to handle this also remove all users from the group, like so:

dscl . -delete /Groups/_developer GroupMembership

If the GroupMembership key doesn’t exist, dscl will create it—and it doesn’t exist by default—so deleting it outright shouldn’t cause any problems.

10
Jul

Dealing with Special Characters in iPhone 4 Graphics Filenames with Subversion

With the iPhone 4’s high-resolution screen, designers need to create two sets of art; the guidelines are to name the files like so: SomeCoolImage.png and SomeCoolImage@2x.png. Unfortunately, if you try to add these files to an SVN repository, the @ symbol throws them off:

$ svn add Icon\@2x~iphone.png
svn: warning: 'Icon' not found

The fix, thanks to the subversion_users Google Group, is to add another @ to the end of the filename, like so:

$ svn add ./Icon\@2x~iphone.png@
A  (bin)  Icon@2x~iphone.png

If you’d like to do this for all of your high-resolution art in a folder, here’s a tiny Bash command for the task:

for x in `ls *\@*`; do svn add $x\@; done
1
Jul

How-To: Run a LaunchDaemon That Requires Networking

I’m a big fan of using launchd to automate things in Mac OS X. That serves me well, as that’s how Apple wants things done moving forward. That said, one of launchd’s biggest shortcomings is a lack of a dependency system. There is currently no way, for instance, to specify in a LaunchDaemon’s property list that the daemon requires the network to be active in order to run. This is problematic for some things, such as a script I wrote to automatically set the computer’s hostname based on the DNS server (more on that later). Luckily, Apple has already defined a function, CheckForNetwork, in /private/etc/rc.common. Here it is in all its glory:

##
# Determine if the network is up by looking for any non-loopback
# internet network interfaces.
##
CheckForNetwork()
{
	local test

	if [ -z "${NETWORKUP:=}" ]; then
		test=$(ifconfig -a inet 2>/dev/null | sed -n -e '/127.0.0.1/d' -e '/0.0.0.0/d' -e '/inet/p' | wc -l)
		if [ "${test}" -gt 0 ]; then
			NETWORKUP="-YES-"
		else
			NETWORKUP="-NO-"
		fi
	fi
}

In your code, simply include rc.common, then call CheckForNetwork as needed. An example:

#!/bin/bash

# Example Daemon Starter
. /etc/rc.common

CheckForNetwork

while [ "${NETWORKUP}" != "-YES-" ]
do
        sleep 5
        NETWORKUP=
        CheckForNetwork
done

# Now do what you need to do.

Note that this will keep the script running indefinitely until CheckForNetwork sets NETWORKUP to “-YES-,” so if there’s a networking problem your code may never execute.

15
Jun

Updating dyld Shared Caches with Radmind: Best Practices

Similar to my last post about updating kernel extensions, you can run into problems with Radmind due to the dyld shared cache. You may see messages like this in your system log:

current cache invalid because /System/Library/Frameworks/WebKit.framework/Versions/A/WebKit has changed

Running the update_dyld_shared_cache command will fix this, but there’s a better way. Sure, there’s almost no overhead to that command, but where’s the fun in that? Here’s a pre-apply script that will delete any shared caches that have changed, which will then be re-built at reboot.

#!/bin/sh

# update_dyld_caches: Inspects the applicable transcript for something that
#                     might cause a dyld cache to become outdated. If it exists,
#                     delete the cache so it's re-created at startup.

DYLD_CACHE_FOLDER="/private/var/db/dyld"
DYLD_PREFIX="dyld_shared_cache_"
ARCHITECTURES="i386 x86_64 rosetta ppc ppc64"

for arch in ${ARCHITECTURES}; do
	cache="${DYLD_CACHE_FOLDER}/${DYLD_PREFIX}${arch}"
	map="${DYLD_CACHE_FOLDER}/${DYLD_PREFIX}${arch}.map"

	if /bin/test -f "${cache}"; then
		if /bin/test -f "${map}"; then
			/bin/cat "${map}" | grep ^/ | sort --unique --ignore-case | while read line; do
				if /bin/test -n "$(grep ${line} ${1})"; then # found a match
					/bin/rm -f "${cache}"
					/bin/rm -f "${map}"
					break;
				fi
			done
		else
			# Cache exists, but there's no map.
			/bin/rm -f "${cache}"
		fi
	fi
done

27
May

Updating Kernel Extensions with Radmind: Best Practices

One of the problems that I’ve run into so far using Radmind to manage Mac OS X—specifically, the Leopard to Snow Leopard transition—is that kextd helpfully starts recreating your kernel extension cache as soon as you modify anything in /System/Library/Extensions. This can be problematic when you’re updating core system files; as you update the 10.5 kernel extensions to their 10.6 counterparts, you don’t want the 10.5 version of kextd creating a cache of 10.6 kernel extensions, especially as the kernel extension cache has moved (from /System/Library/Extensions.mkext to /System/Library/Caches/com.apple.kext.caches/). So, should you handle this? My solution is to stop kextd if I know that I’m updating kernel extensions; that way, they won’t be re-created until reboot. Here’s the script:

/private/var/radmind/preapply/update_kernel_extensions:

#!/bin/sh

# update_kernel_extensions: Manage the replacement of old kernel extensions.
#                           If there are updates, kill kextd and destroy the
#                           caches.

KEXT_CACHE="/System/Library/Caches/com.apple.kext.caches"
KEXT_FOLDER="/System/Library/Extensions"
KEXTD_LAUNCHD="com.apple.kextd"
SYSTEM_LAUNCHD_FOLDER="/System/Library/LaunchDaemons"

transcript="${1}"
result="${transcript}.$$"

/usr/bin/grep "${KEXT_FOLDER}" "${transcript}" > "${result}"

if test -n "${result}"; then #result is non-empty
    # Disable kextd to prevent it from recreating kernel extension caches, which
    # will be re-created at startup.
    if test -n "$(/bin/launchctl list | /usr/bin/grep ${KEXTD_LAUNCHD})"; then
        #kextd is running
        /bin/launchctl unload "${SYSTEM_LAUNCHD_FOLDER}/${KEXTD_LAUNCHD}.plist"
    fi

    # Remove kernel extension cache.
    /bin/rm -rf "${KEXT_CACHE}"
fi

rm -f "${result}"

In its present form, it only works on Snow Leopard, but I’ll be updating it to work on Leopard as well.

30
Mar

Using AppleScript to Automate an iChat Video Chat

I had to write a script to automatically start iChat at login and start a video chat with a specified screenname. I wanted to only start the chat if the user was online and available, and quit iChat on an error or if the chat ended. So here’s the script I have:

using terms from application "iChat"
	tell application "iChat"
		activate
		log in
		delay 5
		set theBuddy to buddy "ScreennameGoesHere" of service "AIM"
		try
			set theStatus to status of theBuddy
		on error errmesg number errno
			set message to display dialog "The user is currently unavailable." buttons {"OK"}
			quit
			return
		end try
		if theStatus is available then
			set theCapabilities to get capabilities of theBuddy
			if (theCapabilities contains multiperson video) then
				send "A user is attempting to contact you." to theBuddy
				delay 2
				tell service "AIM" to make video chat with properties {participants:theBuddy}
				set theChat to result
				delay 30
				try
					set theStatus to the av connection status of theChat
				on error errmesg number errno
					quit
					return
				end try
				repeat while theStatus is not ended
					delay 5
					try
						set theStatus to the av connection status of theChat
					on error errmesg number errno
						quit
						return
					end try
				end repeat
				quit
				return
			else
				set message to display dialog "The user cannot video chat at this time. Please try again later." buttons {"OK"}
				quit
				return
			end if
		else
			set message to display dialog "The user is currently unavailable." buttons {"OK"}
			quit
			return
		end if
	end tell
end using terms from

A couple of gotchas:

  • I tried using video chat instead of multiperson video, but that always returned false. I don’t know why.
  • Once the video chat has ended, you can’t poll its status (hence the try block).
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