I Took a Picture [SF Edition]

HDR of San Francisco with 3 RAW 14Mpx Exposures processed in Photomatix Pro (Unlicensed ^_^ )

This is what 16k miles looks like

Thanks to the great folks at the great circle mapper, i now know what a 16k mile journey looks like.

The Golden Gate

After years of just seeing it in photos i got the opportunity to photograph it myself. It was the culmination of a fantastic day; the end of WWDC and an excellent talk by Buzz Aldrin.

Many people have asked during my journey if i keep a journal. While i don't in a conventional sense, photo's like these will help me remember this experience for a lifetime. 

What isn't always obvious is that the Golden Gate is essentially in the middle of nowhere. There is no easy way to get there from downtown San Francisco without a car, so i had to get my bike on, by chance i was able to rent one at a bike shop near 4th & Harrison. The $400 deposit scared the crap out of me at first, but it was alright in the end.

San Francisco is hilly place, so my plan was to cycle along the Embarcadero, which runs parallel to the shoreline (read: nice and flat). The previous link goes to my little weekend project. I built an app called gpxshare which allows people to upload and share GPX tracks for free. 

This was some what of a rambling post, but i just wanted to share some of these awesome pictures.

Core Data & Multi-Threading, part 1337

So i've made yet another Core Data Discovery, at this rate i might need to write a ebook. Now we all know that the golden rule of using Core Data with different threads is to not share contexts between threads.
So if you need to refer to an object on multiple threads you need to use it's NSManagedObjectID. Thats all well and good, but what if you need to call [NSManagedObjectContext save:] multiple times. Well in short it's gonna suck. Well thats cool you say, i can just use the id anyway ... Not quite. There are two types of ID's, permanent and temporary.
Now in my experience Core Data seems to get confused when you use temporary ID's to look up objects on another NSManagedObjectContext. So really to stop these conflicts we need to get a permanent id, but we need to obtain one of these ID's without saving the NSManagedObjectContext.


Well are you ready for the magic ... Shazam

[NSManagedObjectContext obtainPermanentIDsForObjects: error:]

This awesome method will take an array of managed objects, and give them permanent ID's. From my brief tests the overhead is minimal compared to the traditional save method.

Thats all i've got for today, keep on trucking.

[]'s 4 life

Asynchronous Core Data searches with Blocks

I was recently fortunate enough to be able to drop iOS 3 support on a project. This meant that i could start to play around fully with Blocks on iOS. One thing that has always got on my nerves is that there is no built in support for asynchronous Core Data searches.

Previously i tried to wrap up potentially long operations in a special FRCoreDataOperation a subclass of NSOperation. However this was a pain, as i would then have to subclass it or modify the parent class to provide me with a simple callback when the task was complete.

What i really longed for was the way in which you make Ajax requests in jQuery, that of course requires closures, which are of course provided in the form of Blocks. So after hacking around for a bit i came up with this.

Now this is my first real time using blocks outside of simple things like iteration etc. It means that i can do

Now here's the part where i pat myself on the back. The callbacks are executed on the main thread, after the async fetch request is completed. Plus it gets better, The NSArray, for the onComplete block contains a list of the returned objects that are registered with the NSManagedObjectContext for the main thread, or in other words the NSManagedObjectContext you used to perform the fetch.

Once i touch down in the valley i plan to extend this to manage saves as well, making the basic CRUD operations with Core Data "scroll like butter".

Roaming in jamaica

£6 per MB and it's EDGE, give me strength please.

One flip side this country is a very different to the one I left. But for the most part different for the better.

Going to my grandparents house for the first time in 10 years has been fairly emotional. I'm still expecting to see them around house despite the fact the both have been dead for sometime.

I've compared it to a time machine, as it feels like I've just fast forwarded into the future. One without two people that I had come to know and love so well.

When I landed the lady at customs asked why I hadn't been back in so long (10 years), I'm slowly learning that it's because I knew subconsciously that it would be an emotional roller coaster.

Animating a series of images with CALayer

So you want a to animate a series of images, flip book style. While it is true you can use UIImageView, everyone knows that is for wimps. Real men (& ladies ;) ) use CALayer (like a boss)...

But how? Well you might have some how got in your head that CALayer's contents property supports a NSArray of CGImages. Well this is not the answer, remember that the contents property takes an 'id'as a argument so it supports virtually everything under the sun and then some. Hell, if you felt like making crazy things happen you could just throw a NSData object in there.

Anyways, the actual solution is to use a CAKeyFrameAnimation, to manage the rotation of your images, control the frame rate, and ultimately the duration.

Well all is said and done it should look at this

Drawing text with a Gradient

Problem

You want to draw (unicode) text with filled with a gradient.

Solution

Since my middle name is now "Core Graphics", let me help you out. It's actually pretty simple. Create your desired gradient in a your image editor of choice, and save it as a PNG. Import it into your project and then ...

Yep folks thats it. Now if you find that your gradient is slightly out of place, you can use CGContextSetPatternPhase to help. You of course would use this before your drawing statement. The docs say:

The pattern phase is a translation that Quartz applies prior to drawing a pattern in the context. The pattern phase is part of the graphics state of a context, and the default pattern phase is (0,0). Setting the pattern phase has the effect of temporarily changing the pattern matrix of any pattern you draw. For example, setting the context’s pattern phase to (2,3) has the effect of moving the start of pattern cell tiling to the point (2,3) in default user space.

So when all is said and done you get this lovely effect

Best of all this effect works all the back to iOS 2.0!

Problem: Symbolicate won't ... um symbolicate.

Long live Crash reports, Crash reports are dead. We all love em right, couldn't live without them. But what happens when crash reports go bad. Sadly this isn't a lead up to a blockbuster movie but in fact a real life issue.

As much as a i love Xcode 4, (and i really love it) it swallows errors that symbolicatecrash script spits out. This caused me to send loads of time trying to fix an issue that i knew nothing about.

Well here's the solution. 

1. Do a project clean in Xcode (cmd+shift+K)

2. Delete the entire 'PROJECT/build' directory

3. Go to ~/Library/Application Support/iPhone Simulator/VERSION/Applications/UUID and delete each folder that contains your application name. Be sure to do so for each Version of the SDK.

And then attempt to symbolicate your reports.

I'm led to believe that some genius (who i'll target at WWDC and buy him/her a beer) thought it would be a great idea to use Spotlight to find dSYM files. Sadly i don't believe they thought (or could) apply any sort of search order, leading to spotlight returning random binaries. (When good ideas go wrong).

FYI. If your a member of the Xcode Team, i genuinely appreciate all the work that you folks put into 4.x.  

Coming to America

So after managing to avoid the states in all forms for well over a decade it's time to go back. I'll be able to enjoy the benefits of naked body scanners, and requests to show my papers.

Anyways the trip is split into 4 parts, over two months.

A. New York city
B. Jamaica
C. Los Angeles
D. WWDC in San Francisco.

Interestingly, I have no return ticket, not because I'm planning on becoming an illegal (please note TSA) but because I'm not sure if I'm coming back to the UK or if I will carry on heading west, and reunite myself with the Chinese people (they miss me you know).

The first leg is booked for April 18th, so as song says I'll be "new York da da da dada da new York" HOV ...

While WWDC should be a blast the most emotional part will be going back to Jamaica almost 10 years to the date that I left.

Bon voyage

Jonathan @ 24

Well would you look at that. I'm 24 years old. Kinda strange I might add. Well being the kinda introspective dude I am, I thought I would look at my highlights over my 23rd year on this planet.

....

Yeah so that's it, fascinating don't you think. But seriously my 23rd year was a good year, and I'll strive to make my 24 th even better, with the usual smattering of travel adventures, odd situations and hard core forking.

Creating Push Notification certificates that you can use .cert -> .pem

Thanks to this helpful the post, the rest of the world knows how to convert .cert files (the ones the ADC gives you) into .pem files, the ones you need to actually send notifications to apple.

To further aid this, threw together a little shell script that takes two arguements, the certificate.p12 file and the private key.p12 file and creates a apns_certificate.pem file. Saves a bit of typing and also gives you a hard copy of the commands needed to create the certificates

From Russia With Code

I had the privilege of travelling to Kiev, Ukraine for Business. For me this was first trip to eastern europe. Thus far i had only been as far as Hambug, Germany. Which even at it's height was in West Germany, and i believe in the UK control area, so it wasn't even that different. I'm writing this on the plane but i expect the culture difference to be close to that of china, but with out the squat toilets ...

In a way this is good prep for me as i've always wanted to ride the train from Moscow all the way to 北京, and maybe even on to Pongyang, DPRK (insert joke here).

The Standout things

* Everyone seems to like drinking tomato juice, in lieu of fruit juice.

* Haven't seen a samovar yet.

* Yes, they drink a lot of vodka.

* You never drink vodka without eating ... unlike the UK

* It's not as destitute as you would think

* A lot of people speak english, especially in service industry.

* My Russian is awful

* It kinda looks like that level from Call of Duty 4 modern warfare, you know, this one, seriously.

Sad i was only there for three days, three cold days, where i didn't go outside much. But hopefully i should go back in the summer so i'll have more to say and show then.

Why does Darren Bent cost £18 Million?

I think Bent is good goal scorer, with a proven record. But i don't think he's worth £18 million quid. Thats not an insult, i'm just old school and think that's a lot of money. (I don't think Chris Smalling is worth £7 million either, that is an insult ... to man utd ^_^, thanks Sir Alex we really like Dembele) It's a good question don't you think. I'm no accountant, but lets try and work this out. I'm always amazed at how a football clubs legal people arrive at these figures.and have felt that while they are crazy there has to be some kind of reasoning and logic to them.

It is slightly hard to do this as few things are actually official, but as Rafa says lets work with the facts (that are mostly rumours).

Darren Bent is rumoured to earn £50k a per week, and had 2 years left on his contract at sunderland.

That means that his contract excluding any bonuses or commercial rights is worth about £2.6 million a year or £5.2 million. I believe this should be his 'book value', and the value that would stated on Sunderlands accounts.

Next Darren's move to Sunderland from Tottenham cost £16 million, with a cash component of £10 and the additional £6 million to be paid in various (i assume) performance related bonuses. Now i would guess that a club like sunderland structured the majority of these payments to be done over a period of time, being that Bent only left a year and half ago, they probably haven't paid this total sum yet.

Lastly as reported, a cause in the deal with Tottenham, was that Sunderland had to pay them 10% of his next transfer fee, something they would also need to take into consideration when negotiating with Aston Villa.

So lets do some basic addition with the numbers above

£5.2m (contract)
£10m (purchase price from spurs)
£15.2m

Now lets say that Sunderland have a policy of trying to maintain a profit margin of around 10% margin on player sales, that puts us in a range of £16.72 million.

Now we are missing one thing, Spurs cut. Thats 10% right?

10% of 16.72 million is £1.72 million

Which i assume sunderland passes on to Villa, so we get £18.39 million. If if they can't legally do this £16.72 still isn't far off the headline £18 million figure that we see in the press.

In fact depending on how much sunderland and already paid tottenham in bonus related payments, they might not have even made a profit. Also i dont know if Darren's 50k p/w wage is before or after tax, because if it is after tax, the value of his contract to the club is effectively doubled. due to the 50% tax rate.

Not accurate, not throughly researched, but certainly interesting.

Next, how the hell did they work out 'CR7' was worth north of £70million?

If you got any insight for me please share either on twitter @veritech or in the comments.

OpenGL Docs

I was about to dabble with OpenGL in recently, when i made a horrific discovery.

Happy Friday :D

NSNotificationQueue, Coalescing and SIGABRT

So it's one of those days, your steaming along adding a feature and then bam, you hit a road block. Well here was mine.

I've come to love many cocoa API's over the last year. One i've been late to embrace is NSNotificationQueue. What can i say that hasn't already been made clear ... it's a queue for notification objects ... well almost it has one particular feature that makes it totally awesome, Coalescing.

Coalescing is useful for when you want to call a method multiple times but only have it execute it's action once every so often. Since i've started coding for iOS i've been a fan of simply calling [UITableView reloadData] to refresh my table views, it's simple concise and i don't have to worry about index paths etc. However if you are drawing complex cells, and you need to call this method while you process some data you really don't want to happen every single time, the user isn't playing COD, they just want to see their data, and not have it flick around. So in my UITableViewDataSource classes i do this ...


With the handler to the reloadNotification calling the actual reload method. This means that in one area of my app, where i am listening for NSManagedObjectContextObjectsDidChangeNotification (gotta love cocoa conciseness )the reload method gets called just once instead of 10+ times.

Awesome right ....

Well there is a problem, you might have noticed that enqueueNotification: takes a postingStyle. This calculates when in the duration of the run loop the queue will attempt to deliver your notification. Because i want my Run loop to be a free spirit and not care about what my crazy background threads were doing i would usually choose NSPostWhenIdle. Well i did till today.

The problem is the UITableView that this data source is assigned to can be dealloc'd at anytime, and while my dataSource is a good cocoa citizen and removes it's self as an observer before it is dealloc'd the notification has already been assigned it's target and is waiting till the run loop is idle ... read waiting till after my object has been dealloc'd. This of course means the the objective-c runtime attempts to call the reload method on dealloc'd object, and we all know what happens when that happens ... Well i thought i did. I code with NSZombieEnabled on, so in such a situation i expect to see a nice friendly message saying i've sent a message to an invalid object ... I got that message ... sometimes. Instead 9/10 times i got a big, fat, bold SIGABRT.

Oh, but you have stack traces ... um no. When crap happens in the objective-c runtime, you close your eyes and pray that they will go away, well thats what i do.

Anyways the solution was to ensure that notification was dispatched as quickly as possible, so NSPostNow was a much better fit. My professional($_$) opinion is that unless you have a long running object (ie the app delegate) or a singleton, never use the NSPostWhenIdle.

Conclusion

NSPostNow > NSPostWhenIdle
(9 out of 10 times)

2010: My Highlights

Well would you look at that, the year is over already. Before we condem it to history i wanted to have a quick look back at this year.

Float-Right (aka my career)
I've been self employed for entire year! Thats right folks a whole year. In that time Float-Right has really grown. While i'm not quite groupon, and i haven't bought that Aston Martin Rapide yet, i'm happy with what i've been able to achieve in that time. I've had some help mind you, not only in the form of my Mum, who has kept me snug with regular cups of tea, but also my small but loyal twitter following who make up for the lack of work colleagues.

2011 should see Float-Right do more work internationally, not only in terms of client base, but also in terms of where i will physically be located (thats right, i'm going back to Espana!). Also i hope to finally meetup with the rest of the iOS/Mac dev community at WWDC this year. As a result please send me work! Flights to San Francisco, hotel stays, and WWDC tickets are not cheap. Even my budget travel ethos doesn't cover me on this one.

Travel
In 2009 i travelled to China, Hong Kong, Barcelona,Spain & Paris,France. I thought that was fairly amazing. Well i think it's fair to say i've had another good year, visiting Amsterdam( Netherlands), Barcelona(Spain), Sevilla(Spain), Tel Aviv & Jerusalem (Israel).

Despite now being essentially banned from a number of nations thanks to my visit to Israel, my list for 2011 is even bigger. Argentina, Australia, USA, Switzerland, Norway and of course my new home (in the sun), Sevilla.

Moments
Have had a lot of interesting moments and times this year, but here are some of my highlights.

* Encouraging Ezra (@ezrabutler) to take a boat trip in international waters for his birthday ... this was about 1 month before the infamous flotilla incident

* Meeting Joaquin. Not that it was bad, it was just overwhelming.

* Hanging with Jason and his friends in Sevilla, he really helped make that experience amazing.

* My "lovely" trip to sunny barcelona, hint, it wasn't lovely, and it damn sure wasn't sunny.

* Being confused for a homeless person on the streets of Barcelona at 2am.

* Meeting Jonathan/Joe (@improvmonkey), full of interesting facts and views on life, the world, and the babylonians.  I've never met a grown man that can party like that. I can't mention Joe without mentioning some other folks i met on that trip; @ahoova @llan_peer and @guy.

* Amsterdam with the lads, while people find this hard to believe i don't smoke, but that was hilarious. Especially the trip to the park on the last day. Shout out to @andrew_francis & @jai_morjaria. We gotta do that again.

* The sheer number of people that i met in Sevilla, too many to name them all (well i might have forgotten some of their names ... ). Strangely two of my favourites were both Aussies, Amy & Jardana.

* While i also met her in Sevilla, she deserves a bullet point all to herself, Serpil, aka El Professora, the woman that helped beat my spanish into shape, while also showing me what being truly multilingual looked like. She was also a really nice person!

* Buying stuff in a spanish shop in chinese. Absolutely hilarious.

* FOWA after party, that's always funny.

=======================================================
Anyone else noticing that all the good stuff happens overseas ... i'm just saying
=======================================================

* Geeky i know, but i finally purchased my first ever Macbook pro :)... which i put a rather large dent in three weeks later :(

* Living in a hostel(s) for two weeks. It was awesome at first but really started to get depressing towards the end.

* Finally having a piece of published software! Only took 22 years.

* Having a flight cancelled for the first time in my life.

* Watching the sunrise on beach in Tel aviv.

* The way people (who aren't from California) get excited when i tell them i make iPhone apps for a living, (putty in my hands i tell you...)

* My cafe con leche experience ... aka hot milk with a tea bag in it. Priceless.

* Completely stopping Web Development, i can't explain how great that is.

* Meeting the Girls as @andrew_francis and i call them, hilarious night. Good people.

* Saying the Stweetfight app would only take a couple of hours (thanks @samwilliamh)

* Doing a standup like performance for a roof terrace full of germans.

Well that made me smile, if no one else. So lets give away some awards.

My most hilarious moment of 2010 ...
Watching Nykia drop off a chair. Being 2010 it's on video of course

My most depressing moment of 2010
Letting go one of my early clients.

My happiest moment of 2010 ...
I can't pinpoint a single moment, but as the above shows all the time i spent outside of the UK were my happiest times. (i'm still game for the passport swap if you are)

My Saddest moment of 2010 ... 
My grandmothers funeral, never have i shed that many tears in so little time

Goals for 2011
I have many, being the continuously improving sort of person i am, but here are a few.

* Go back to spain (por todos tiempo)
* Go back to China (on my to the DPRK perhaps ....)
* Build a Mac App
* Discover this work/life balance that people talk about
* Go somewhere i haven't been
* Improve my Spanish & Chinese, especially my ability to read the latter.
* Starting learning Arabic
* Pray a little/lot more, at this rate someone might confuse me for an atheist! I'm actually a christian shock horror!

To everyone, best wishes in 2011. Don't forget it's just like 2010, but your older this time ^_^

Offscreen drawing on the iPhone using NSOperations, CGImage, CGLayer

What?

Creating and or modifying images offscreen or in a background thread.

Why?

Chiefly for performance. The main thread of an iPhone application is usually fairly busy doing all sorts of things. By rendering complex images in the background, you can do all manor of things. In my case I wanted to know how to render an image larger than the size of the device screen, and then save that image to disk.

For my fellow lovers of NSOperationQueue(aka possibly the most awesome class in Cocoa), this allows you to bundle image processing and generation in to NSOperation subclasses or if you like the new hotness a block, and add it to the queue.

How?

Well with a lot of C. If you have ever overridden UIView's drawRect: then most of what is below should make perfect sense.

First thing is first, as we want to operate on our own thread we have to create everything ourselves. Primarily that means no quick calls to UIGraphicsGetCurrentContext().

The key thing to remember is that the drawing coordinates are inverted. This means that CGPoint(0.0f,0.0f) is actually the bottom left not the top left corner. I'm lead to believe this is a hold over from the Postscript drawing system that originated on the mac, and this is how the big boys do it. So stop whining and code.

Nicely it would appear that the UIImage representation methods automatically invert the image, so you only have to invert your coordinates for CGContext drawing calls.

Exactly How?

This is the process

*Create a CGColorSpace

*Create a CGBitmapContext

*Create a new CGLayer

*Get the the CGLayer's context

Draw into the context as you would normally, using the CGContext methods

*Render that CGLayer into the CGBitmapContext

(if you want an image)

*Create a CGImage from the CGBitmapContext

*Convert the CGImage into a UIImage

*Use one of the UIImageJPEGRepresentation or UIImagePNGRepresentation methods to get an image that can be saved to disk or sent over the wire etc.

NOTE: This code will not work unless you have a image named sample.jpg in your bundle or change the assignment to the backgroundImg variable.

Sample code

Go forth and code.

Ultimo Videos de Sevilla

My last videos from sevilla, headed to a Flamenco club with some new folks after my flight got cancelled, enjoy

End of an era

This morning I found out that my grandmother died. While it's a sad event in and of itself, bares an additional level of significance.

It signals the end of Samuels surname. My grandparents only had girls, 3 of them to be exact. While my surname might be Dalrymple, I identify more with my maternal side of the family, and felt more in touch with that side of my family.

It was also that side of the family that was the first to come to England during the wind rush years, and is partly why I hold a British passport, and thus am able to live in Sevilla.

My grandparents did a lot for me, not only did they raise me but much of my personality and drive developed as a result of their influence. So I owe them a lot.