The coding life with Giordano Scalzo

[giordanoscalzo]

Print all iOS fonts in Swift

Handy function that I always forget

func printFonts() { let fontFamilyNames = UIFont.familyNames() for familyName in fontFamilyNames { println("------------------------------") println("Font Family Name = [\(familyName)]") let names = UIFont.fontNamesForFamilyName(familyName as! String) println("Font Names = [\(names)]") } }

[giordanoscalzo]

FlappySwift: it's just a matter of communication

Last Monday after seeing this amazing WWDC 14 with the friends of NSLondon, I was so excited to trying this new language that, when I saw this tweet, I thought was the perfect way to test drive Swift.

At around Midnight, when finally I had Xcode 6 installed, I selected "New Project" and I started to convert a FlappyBird clone I did few months ago.. After a couple of hours, at around 2AM, when I was pretty satisfied, I pushed the code to Github, replied to the tweet then I went do sleep.    When I woke up, I checked my emails and I was very happy seeing that more than 100 people had starred my little project; but few hours later I noticed that another guy had had the same idea (and the same project name), but in contrast with mine, his was with more the 1000 stars! Ok, to be fair his version had also pipes, and the README was prettier, but that wouldn't have been enough to explain such success. Yep, the answer was simple: that guy, instead tweeting it only, put the link in HackerNews, where quickly had had reached the first page.

To wrap up, it doesn't matter if you are quick, it doesn't matter if you are good... it needs but it's not enough: it's the way you present your product and how you communicate it :-)

[giordanoscalzo]

[giordanoscalzo]

[ios-goodies]

Articles

Floaty Balloon: How to Build a Flappy Bird Clone in 2 Hours, by Nick Lockwood

Calling Blocks Inline, by Karol Kozub

Objective-C isn’t what you think it is (if you think like a Rubyist), by Rap Genius Engineering Team

Deleting Objects in Core Data, by Marcus Zarra

...

[giordanoscalzo]

Source code for a Flappy Bird Clone

FlappyBirdClone

A Sprite Kit Sloppy Flappy Bird Clone

While the whole world went crazy with a quite boring, but temendously difficult game, I was busy studying Functional Programming an iOS. Just the day before the author pulled it down from the store, I downloaded it and after a couple of games, I wondered how much time I would had need to create a simple clone using Sprite Kit. So, I waited mi kids went to bed and I created a new project with AppCode...

Ok, first implementation done! Not perfect, code is definitely bad, but for a few hours project is good! The app is still in progress, next step clean a bit the code and add sensor to count the number of pipes passed.

Here it is the code: 

https://github.com/gscalzo/FlappyBirdClone

[giordanoscalzo]

Cross fingers!

[giordanoscalzo]

Filtering iOS Simulator Console message

Are you relying on some kind of messages you put in NSLog to see what are happening in your work in progress app?

Are these messages buried inside a lot of other messages?

This made my day:

tail -f /var/log/system.log | grep "EVENT_MARKER"

Neat, isn't it?

[giordanoscalzo]

Compendium to previous post.

Anyway, for all busy developers without the time to read the linked post, we can summarise in a sentence as:

always define the version for everything (CocoaPods, pods and Ruby).

[giordanoscalzo]

iOS dev tips: CocoaPods

Premise: I'm not anymore so young (I'm doubly young :-)), and I started to love computer with ZxSpectrum and than Dos (coming out: I've never owned an Amiga :-().

So my dev life cycle is mostly controlled by Cli commands.

In this serie of (short) posts, I'd like to note down all common tools I use in my projects.

First, and maybe, most important one is my favourite dependency manager: CocoaPods.

CocoaPods is like gem+bundler ora working version of Maven (joking :-)).

All it needs is to install the gem, create a simple configuration file with the dependencies, run pods install and... Voilà!

No more fight with external libraries, Arc or non Arc!

Now and them some glitches still appear, but nothing that a

rm -rf Pods && pods update

can't resolve.

[giordanoscalzo]

Corebluetooth tips: publish only for iPhone 4S or greater

It's obvious, but, as usual, I just forgot it :-)

To force an app to iPhone 4S or greater, add the key bluetooth-le under UIRequiredDeviceCapabilities entry.

The full the filter grid for the various devices can be found in iTunes Connect Developer Guide's Appendix C - Device Compatibility Matrix.

[giordanoscalzo]

Corebluetooth tips: how many devices can I manage?

Ok, this is the question, given the lot of activity done on StackOverflow (for example here).

There isn't an official answer from Apple, but during last Apple Technology Forum, I asked  directly to Brian Tucker (Apple CoreBluetooth Senior Manager). Brian was kind enough to give me an articulated answer:

there is no limit in concurrent connection, but problems rise during data transfer, because all connections share the same bandwidth, obviously.

Moreover, Bluetooth and Wifi share the same antenna, so the number of contemporary transferring devices are affected by the wireless activity.

Given these informations, a good rule of the thumb is to consider safe until about ten concurrent peripherals transferring data.

[giordanoscalzo]

Corebluetooth tips: can I go in background?

Of course yes!

Simply add the key bluetooth-central under UIBackgroundModes and every notification is received in background too.

This is very useful to create some polling methods, implementing a sort of timer in our Bluetooth device that send a notification every a defined time interval, to wake up the app and do whatever we want.  

[giordanoscalzo]

Not quite a fan of static code analyze, but OCLint seems interesting.

[cocoaheads]

Xcode 4 Shortcuts

[giordanoscalzo]

Awesome Xcode shortcuts sheet

[giordanoscalzo]

Corebluetooth tips: after cancel a Peripheral, the device isn't shown during scan

This is a strange one:

when you disconnect a peripheral calling cancelPeripheralConnection, thedidDisconnectPeripheral delegate method is invoked, but the peripheral doesn't advertise itself for about 30 seconds.

This happens because in this time frame, iOS doesn't really close the connection, so, from the peripheral point of view, the pairing it's still established.

Apple didn't explain this behaviour and a lot of speculation was done; the explanation considered more likely believes that it prevents occasionally glitch of connection.

Anyway it seems than in iOS 6.1 Beta4 the timeout is reduced to a couple of seconds.

[giordanoscalzo]

CoreBluetooth tips: reconnect a device

Unlike previous version of Bluetooth, in Low Energy version almost everything must be managed by the application layer. It's quite easy to understand scan, connect and discovery process, because there is plenty of tutorial and blog posts about it, but the reconnection stuff it's a different kettle of fish.

As usual, after found the way, it's very easy, but I had to dig deep into Stackoverflow before see the light.

First of all, we have to save the uuid of the paired device, using a local db, NSUserDefaults, a file...

Don't forget to transform uuid to string format before save it:

NSString *pUuid = (__bridge NSString *)(CFUUIDCreateString(nil, otherPeripheral.UUID));

When the app restart, retrieve the identifier, transform it into CFUUIDRef

CFUUIDRef cbuuid = CFUUIDCreateFromString(nil, (__bridge CFStringRef)(uuid));

and send retrievePeripherals message to CentralManager with the list of devices to reconnect:

[manager retrievePeripherals:@[cbuuid]];

After that, the relative callback is then called:

- (void)centralManager:(CBCentralManager *)central didRetrievePeripherals:(NSArray *)peripherals{ for (CBPeripheral *peripheral in peripherals) { [central connect:peripheral]; } }

The connect message is an inexpensive method, and it's useful also to reconnect when a device go away from iPhone.