Category Archives: Mac

Mac App Store: “An unknown error has occurred”, iCloud: “Unable to sign in because of a problem communicating with iCloud. ” on genuine Mac

So perhaps you’re getting these errors?

Unable to sign in because of a problem communicating with iCloud.
Try signing again.

App Store
An unknown error has occurred.

The server encountered an error processing registration. Please try again later.

The server encountered an error processing registration. Please try again later.

Perhaps you may say, “Gasp! This is supposed to be a hackintosh issue, and not an issue on genuine Macs!”

Fear not, my friend, if you have committed the ‘grievous sin’ of moving your Mac’s hard disk into another Mac. (As a penance, say 10 hailmarys quickly.) For you see, on occasion, Mac may get confused about your networking devices when you do this.

What do networking devices have to do with all this? If you read hackintosh forums, you’ll see that Apple seems to use your primary ethernet network card’s MAC address to identify the machine. And communicates the identity in some shape or form when you log into the aforementioned services.

Problem arises when your Mac’s primary ethernet card cannot be identified.

Cure for your transgression? Aside from those hailmaries, you’ll also want to delete (or move aside, or rename) /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist. Then reboot. Behold! This file should be magically regenerated, and your access to iCloud and Mac App Store should be restored.

You’re welcome.

Naturally I’m not responsible if deleting this file harms your Mac, or if you do it yourself in process of deleting this file. Have an expert around. Then again, if you did move the disk around, you probably are the expert.

“To update this application, sign in to the account you used to purchase it.”

Mac App Store started rejecting updates for some apps. It offers “Update” button, but then rejects updating. The dialog on the image is common if a different Apple ID was used to purchase the app… except if that were the case, it’d be mentioning the exact Apple ID it wants be to update with.

“To update this application, sign in to the account you used to purchase it.”

And, another problem: the apps were used using the only Apple ID I use for App Store purchases.

So far, the only certain recourse was to delete the app and redownload it. If it’s associated with my Apple ID (double-check that it is!) there is no problem — the app will be newly installed and you’re good to go. Updates also only appeared when I checked the “purchases” tab, not when I went to the “updates” tab.

A hacker’s note: The wording of the error is strange. You see, it only mentions an account — which may refer to your local account as much as it can refer to an Apple ID. So I went and played with permissions, changing the permission for “everyone” to “read & write” for the application in question. For a few apps, update then went through. For a few, it didn’t.

The above is, naturally, from the “Get info” dialog on the app.

EDIT Oct 11 2012, 14:36 CET: User nikv has a helpful tip:

This error can happen if Settings -> Spotlight has the Macintosh HD in the Privacy section (not to be indexed). Reason being App Store uses Spotlight. If you don’t do this and Spotlight can index the Apps then it finds the updates and works okay.

EDIT Oct 11 2012, 14:58 CET: Also, while trying to figure out why Spotlight is so slow to starts indexing again on my machine, I found a thread that mentions the problem from my post. Their solution? Delete contents of /var/folders. Not the /var/folders directory itself, but its contents.

EDIT Oct 11 2012, 15:30 CET: You may need to restart your machine. (I just quit App, and killed storeagent process, but your mileage may vary.)

Unrelated but helpful tip: sudo opensnoop -n processname helps you see filepaths that a process accesses. Useful with mdworker.

Exploring Apple’s customization of titlebar in Xcode 4

As you may have noticed, Xcode’s NSWindow does not actually have a single representedURL; it has two, the project and the current in-project file.

So how did Apple achieve that?

First things first, you can start figuring that out by yourself by asking your window’s contentView for its superview. Although undocumented, enough apps seem to be playing around with this (including Xcode) that I presume Apple would be reluctant to change something important here.

Second, I’m not going to actually show you any code just yet. Perhaps in a future blog post; I did start writing something, but it’s unfinished.

Third, there is no third: let’s get to it.

Hacking tools

Playing with contentView‘s superviews can only get you so far (although, you may be able to hack something anyway). Injecting code in form of plugins into Xcode is possible, as proven by JugglerShu’s XVim.

But there’s a nicer way.

Say hello to F-Script. It’s a nice scripting language and let’s-call-it mini-IDE in itself, but there’s something far more powerful it can do.

On F-Script

It has a full fledged object browser that uses introspection to figure out what the hell exists in the view hierarchy. It also has a nice view picker so you can easily access the exact view that you’re playing with. Python may be neat for programming, but this one is just smashing for debugging GUI apps.

F-Script is not intended to be used as a standalone dev environment however; you’re supposed to put it into your app and use it at runtime. Kind of like what you can do with Python already… except this one comes with a runtime debugging GUI out of the box (and the aforementioned view picker!), and is pretty dedicated to playing with Cocoa and Objective-C (while Python can play with it through its PyObjC bridge – powerful, but not the best way to do it; also, method names become lengthy and weird when written in Python).

Note that I, for now, have absolutely no experience with F-Script as a programming language, and I don’t intend to learn it too much for now, just as I don’t intend to learn all nuts and bolts of GDB. It may be nice, but for now, it’s far, far, far more amazing as a debugging tool.

Okay, so where does playing with Xcode come in?

Unfortunately, not in the form of injecting the debugging code into Xcode and playing with it. This is the loveliest part of F-Script, however; you can inject it into any app and inspect how it works, see runtime class definitions, send messages to existing objects, etc. But not with Xcode, because of some magic that Xcode is doing causing F-Script to crash Xcode.

Side note: injection of F-Script is done via gdb. The F-Script Anywhere automator workflow intended to be put into ~/Library/Services actually consists of figuring out frontmost app’s process ID, constructing some gdb commands and running gdb. gdb commands used involve attach to existing process, then calling Objective-C method -[NSBundle load] on /Library/Frameworks/FScript.framework, and finally calling +[FScriptMenuItem insertInMainMenu] and detaching. Quite ingenious!

Finding the beast

Let’s get back to business. Although Xcode crashes, view inspector of F-Script works long enough to let us know the name of the class implementing the custom view Apple uses in the titlebar for displaying two “represented URLs”. A-ha! DVTDualProxyWindowTitleView, we’ve found you!

Now, where could this be defined? Let’s explore various private frameworks found in Xcode using class-dump (install it from MacPorts). And voila! Using class-dump we can also see that it’s used in… DVTDualProxyWindow, a subclass of NSWindow. Wonderful!

Now, just trying to load this framework into standalone fails miserably and returns NO. At least for me. otool -L told me which frameworks this one depends on… so I loaded them first.

About the beast

Finally, DVTDualProxyWindow is a subclass of NSWindow which apparently overrides -setTitle: to do nothing, overrides -setRepresentedURL: to be used for the ‘project’ URL, and defines new method -setSecondaryRepresentedURL: to add the ‘document’ URL. Both of these methods are just talking to DVTDualProxyWindowTitleView. We don’t really care what happens behind the scenes; it’s just a regular view. But let’s see if it works.

Open F-Script app. Right click on the toolbar and choose ‘Customize’. Aside from customization sheet, a new window appears titled ‘Custom Buttons’. Pick one of ‘CustomX’ buttons, and select ‘Block…’. (Of course, prior to that, in the toolbar customization sheet, drag the picked button to the toolbar… you know, so you can click it.)

Now, paste in the following code.

Testing the beast

[:selectedObject | 

(NSBundle bundleWithPath:'/Applications/') load.

(NSBundle bundleWithPath:'/System/Library/PrivateFrameworks/DataDetectorsCore.framework') load.

(NSBundle bundleWithPath:'/System/Library/PrivateFrameworks/DataDetectors.framework') load.
(NSBundle bundleWithPath:'/System/Library/Frameworks/SecurityInterface.framework') load.
(NSBundle bundleWithPath:'/System/Library/Frameworks/Carbon.framework') load.
(NSBundle bundleWithPath:'/System/Library/Frameworks/CoreServices.framework') load.

errorPointer := FSObjectPointer objectPointer.
(NSBundle bundleWithPath:'/Applications/') loadAndReturnError:errorPointer.

" printing out an error: 
   errorPointer at:0.

"win := ((DVTDualProxyWindow alloc) init)."

win := DVTDualProxyWindow alloc initWithContentRect:(125<>513 extent:383<>175)
                                   styleMask:NSTitledWindowMask + NSClosableWindowMask + NSMiniaturizableWindowMask + NSResizableWindowMask

(win setRepresentedURL:(NSURL fileURLWithPath:'/Applications/')).
(win setSecondaryRepresentedURL:(NSURL fileURLWithPath:'/Applications/')).

"Instantiate a button, put it in the window and configure it"
button := NSButton alloc initWithFrame:(247<>15 extent:90<>30).
win contentView addSubview:button.
button setBezelStyle:NSRoundedBezelStyle.
button setTitle:'Boo'.
button setKeyEquivalent:'\r'.

"An example of using F-Script blocks to handle click on button. Ignore it."
conversionScript := [(form cellAtIndex:2) setStringValue:(form cellAtIndex:0) floatValue * (form cellAtIndex:1) floatValue].

" From docs: "
"The [...] notation creates an object of class Block which represents a block of code that can be executed later (Block is an Objective-C class provided by the F-Script framework). In our block, we simply get the values of the fields in the user interface objects, perform the computation (simply involves multiplication) and put the result in a UI element.

"An example on how to add handling for button click. Ignore it."
"Make the script the target of the button.
The script will be evaluated when the user presses the button"
button setTarget:conversionScript.
button setAction:#value.

"Show window"
(win orderFront:nil).


Click on the ‘Run’ button, and type in ‘nil‘. (You don’t really care about the selectedObject, but I did not study F-Script long enough to avoid it.)

Hopefully this gives you enough idea to debug with, explore with, as well as an idea on how to implement dual-representedURL windows. Good luck and have fun! 🙂

Getting year, month and day out of NSDate

For some reason, Apple didn’t provide an easy way to extract day, month and year from an NSDate. Probably because they think OS X shouldn’t be Western-centric and presume a Gregorian calendar (although they could have simply extracted this data from current locale). Here is a simple category that allows just that.

// NSDate+IVDateComponents.h


@interface NSDate (IVDateComponents)

@property (nonatomic, readonly) NSInteger year;
@property (nonatomic, readonly) NSInteger month;
@property (nonatomic, readonly) NSInteger day;
// NSDate+IVDateComponents.m


@implementation NSDate (IVDateComponents)
	unsigned units = NSYearCalendarUnit;
	NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
	NSDateComponents *components = [calendar components:units fromDate:self];
	return [components year];
	unsigned units = NSMonthCalendarUnit;
	NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
	NSDateComponents *components = [calendar components:units fromDate:self];
	return [components month];
	unsigned units = NSDayCalendarUnit;
	NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
	NSDateComponents *components = [calendar components:units fromDate:self];
	return [components day];

Note that this code is very Western-centric and always presumes the Gregorian calendar. Sue me.

What I’m missing in Xcode4?

I’m a big fan of Xcode3. Xcode4 is a step in the right direction for me, though. Not so much as it would be when I started with Mac and iOS development, but still, it’s ok.

However, there are large omissions and important bugs that are heavily influencing my productivity.

  1. Removed Right-click, Find In Documentation. (Update on April 1st 2011, 16:42 CET: Alt+left-click is a replacement for this.)
  2. Removed Command+shift+up to switch between header and source. Assistant views are not a replacement since I work on Macbook, which doesn’t have all that much screen real-estate, especially, when you have the File Navigator on the left. (Update on July 12th 2011, 16:21 CET: Use Ctrl+cmd+up, or three-fingers-down-to-up touchpad gesture.)
  3. No ability opening multiple Get Info dialogs on the screen for different project Targets. In fact, Get Info was removed and replaced with (admittedly superior) way of editing build settings.
  4. When autocomplete lists tons of options, Page-down (Fn+Down) does not work. That’s right, you can’t scroll over a screenful of symbols at a time.
  5. Command+shift+b has been reassigned to … get this … Build & Analyze. Ok, that needed a shortcut (maybe), but Command+shift+b used to be the shortcut to open “build progress” output dialog.
  6. Build progress is now assigned a navigator; that is, hit Command+7 to get it. However… the Editor view does not automatically focus on latest build progress and.
  7. Closely related to previous item: there is no obvious shortcut for switching focus between Editor and Navigator. I really want to quickly choose a file, to quickly choose a build log, and to quickly choose an issue from the list. While this is not something that used to exist in Xcode3 (or at least I couldn’t find it) it is still something that would be highly useful. Open Quickly – Command+Shift+O – is not a substitute.
  8. I really miss the old “Groups & Files” view. Not a big deal, but having that as an alternative to the new Navigators view would be excellent.
  9. While autocomplete got even better, Command+doubleclick is extremely dumbed down and cannot guess that in [[NSString alloc] initWithString:@"something"]; attempting to find initWithString in header probably means NSString‘s -initWithString:, right? Well, if you have another initWithString: in another class, Xcode4 will ask you which one you refer to (despite [NSString alloc] being declared to return NSString, thus there being no dillema whose -initWithString: needs to be used).
  10. Despite introducing tabs, they are next to useless: hard to open, and with no obvious keyboard shortcuts to switch tabs or close tabs.
  11. added March 18 2011, 14:12 Oh. Right-click, Add Files to “projectname.xcodeproj” does not take into account parent group path anymore. That means, despite configuring that pesky Window Systems/iOS group to point to path “relative to group” and pointing to “windowsystem/iOS” filesystem folder, Add Files dialog will no longer default to that folder. Meaning I nevertheless have to dig around the filesystem to find the relevant files.
  12. added March 18 2011, 14:40 You can no longer easily access full path to a currently open file by right-clicking on the titlebar. This is important in case error log refers to system-wide installed header file, which you go and happily change without affecting header file that you should be changing — the one in a subproject.

These are just some omissions that significantly reduce my productivity compared to Xcode3. I sincerely hope they will be patched by Apple, otherwise I’ll simply have to do without them. There’s no other way: iOS devs (and to some extent Mac devs) are hostages of the latest SDK which ships only with the latest IDE.

Upotreba Objective-C u igrama; moje mišljenje

A short Croatian language opinion post on use of Objective-C in games

Dobio sam nedavno pitanje o tome da li se isplati učiti Objective-C (u kontekstu igara).

Moje je mišljenje da Objective-C ima deset puta logičniju internu strukturu nego C++, te da je svojom kombinacijom karakteristika dinamičnih i statičnih jezika izuzetno pogodan za pisanje igara. Primjerice, evo stvaranje kapitalnog svemirskog broda koristeći string, i spremanje istog u SvemirskiBrod:
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