Introduction to RubyMotion

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@timriley I’m Tim Riley, I work at Icelab here in Canberra

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Though I’ve just returned from 8 months in the Philippines. Some of the times, it was like this.

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But most of the time, it was more like this.

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But one thing that didn’t change was that I had a lot of this. And it’s the coffee drinking that’s kind of taken me to the point where I can talk to you guys today.

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It was what led me to help build Decaf Sucks. It’s a Rails app, for café reviews.

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Last year I build the native iOS app, in Objective-C. My ﬁrst major iOS project.

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And today I’ll talk about a bridge between these two worlds of tech: RubyMotion. So what is RubyMotion?

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RubyMotion And today I’ll talk about a bridge between these two worlds of tech: RubyMotion. So what is RubyMotion?

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RubyMotion is two things. First, a new implementation of Ruby integrated with the iOS runtime. Includes a static compiler that compiles Ruby into optimized machine code. This part’s proprietary. Second, a set of command line tools create, manage and interactively develop RubyMotion projects. Some of this has been recently open sourced.

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"RubyMotion" "Objective-C" [@ isEqualToString: @ ]; Let’s compare. RubyMotion builds upon the foundation of Objective-C, starting with the basic object model. Both Ruby and Objective-C both have a common ancestor in Smalltalk, so there's a lot of similarities: Open classes, Single inheritance, Single dynamic message dispatch

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"RubyMotion" "Objective-C" == Let’s compare. RubyMotion builds upon the foundation of Objective-C, starting with the basic object model. Both Ruby and Objective-C both have a common ancestor in Smalltalk, so there's a lot of similarities: Open classes, Single inheritance, Single dynamic message dispatch

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[string drawAtPoint:point withFont:font]; Let’s start with message passing

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string.drawAtPoint(point, withFont:font)

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string.send(:'drawAtPoint:withFont:', point, font )

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string.send(:'drawAtPoint:withFont:', point, font )

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class DrawingProxy def drawAtPoint(point, withFont:font) @str.drawAtPoint(point, withFont:font) end end

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.h Objective-C interface .h “header” ﬁles.

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@class Foo - (id)instanceMethod; + (id)classMethod; @end One header for every class. We don’t need them any more. In Ruby, the class deﬁnitions are the class interfaces. In general, RubyMotion gets rid of a lot of the shitwork in Objective-C. No more repeating yourself.

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One header for every class. We don’t need them any more. In Ruby, the class deﬁnitions are the class interfaces. In general, RubyMotion gets rid of a lot of the shitwork in Objective-C. No more repeating yourself.

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Shortcuts

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setFoo: foo=

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isFoo foo?

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objectForKey: []

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setObject:forKey: []=

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view.hidden = true unless view.hidden? Leads to the expressive Ruby code that we love.

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Foundation Classes These classes are the base layer of the Cocoa and iOS libraries. RubyMotion translates these for you.

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MyCustomClass NSObject Kernel

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String NSMutableString NSString Comparable NSObject Kernel

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Array NSMutableArray NSArray Enumerable NSObject Kernel

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Hash NSMutableDictionary NSDictionary Enumerable NSObject Kernel

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Numeric Comparable NSNumber NSValue NSObject Kernel

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Time Comparable NSDate NSObject Kernel

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'hello'.uppercaseString # => 'HELLO' Building upon the Foundation classes means you have access to their methods. Ruby's native interface for these classes still exists, implemented on their foundation counterparts (eg. NSArray#each). This means you can use the standard Ruby interface to these basic objects, regardless of their origin.

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Mutable by Default eg., NSString vs NSMutableString. Be careful of the mutability of the objects returned by Cocoa methods.

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Interfacing with C

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bool BOOL C Types. RubyMotion translates these for you.

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bool BOOL true false C Types. RubyMotion translates these for you.

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char short int long long_long

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long_long? Wait, long_long? What?

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long_long? Wait, long_long? What?

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char short int long long_long

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char short int long long_long Fixnum Bignum

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float double These translations are an improvement. Less for you to consider.

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float double Float These translations are an improvement. Less for you to consider.

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pt = CGPoint.new pt.x = 100 pt.y = 200 C Structures: a ﬁxed set of labelled values in a single object. These are mapped to classes, which you can use in a number of ways, depending on your context. First, by named setter methods on an already instantiated object.

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pt = CGPoint.new(100, 200) Or by ordered arguments during instantiation.

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'Hello'.drawAtPoint(pt, withFont: font) Here’s how you’d pass that structure as a method argument

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'Hello'.drawAtPoint([100, 200], withFont: font) Another shortcut: lets you use an array to pass the structure values in place.

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'Hello'.drawAtPoint([100, 200], withFont: font) Another shortcut: lets you use an array to pass the structure values in place.

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pt = CGMakePoint(100, 200) 'Hello'.drawAtPoint(pt, withFont: font) C Functions are available as methods of the Object class.

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error_ptr = Pointer.new(:object) C Pointers. This is one time when you really feel that you're outside the comfort of Ruby. A Pointer is a memory address that can point to an object. In iOS SDK, typically used as arguments to return objects by reference.

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- (id)addObserverForName:(NSString *)name object:(id)obj queue:(NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *))block; C Blocks. A new language extension from Apple.

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notification_center.addObserverForName( name, object:object, queue:queue, usingBlock:lambda do |notification| # Handle notification here... end ) Should feel pretty natural to Rubyists. Use a Proc objects for the block argument.

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Memory Management This is handled for you automatically. It uses a reference counting method, like ARC, but not exactly the same.

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date = NSDate.alloc.init @date = date If you want to ensure an object's not released, you must create a reference to it, like setting an instance variable. Or set a constant, use a class variable, add the object to a container.

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Enough with the theory. Let’s get some things up and running. Firstly, Installation: Get Xcode from the Mac App Store

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Get the Command Line Tools from Xcode’s prefs.

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Buy and install RubyMotion.

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Hello world

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A Bit of UIKit Let's make a more sophisticated hello world, with a UIViewController custom UIView subclass.

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Interface Builder See http://ianp.org/2012/05/07/rubymotion-and-interface-builder/

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gem install cocoapods pod setup gem install motion-cocoapods

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require 'motion-cocoapods' Motion::Project::App.setup do |app| # ... app.pods do dependency 'JSONKit' end end Declare your pod dependencies in the Rakefile. You can also manually include Objective-C library dependencies using àpp.vendor_project` directive. And àpp.frameworks` allows control over which additional core iOS frameworks you want to use.

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RubyMotion Libraries So much innovation has taken place in just the last couple of months.

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rubymotion/BubbleWrap

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rubymotion/BubbleWrap

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rubymotion/BubbleWrap

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clayallsopp/Routable

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alloy/MotionData

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rubymotion/teacup

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RubyMotion Beneﬁts The expressiveness of Ruby (featured in the library examples we’ve just seen). For us, it’s also a language we already know.

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describe "Application 'helloworld'" do before do @app = UIApplication.sharedApplication end it "has one window" do @app.windows.size.should == 1 end end Ruby’s strong testing tools and culture. RSpec is built-in.

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You get to use your own tools. Opening up the toolset choices also means there’s room for innovation here. Think about all the convenience tools we have in Rails: guard, code coverage, testing tools, etc.

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No more .xcodeproj bullshit. The project structure is simpler and neater, better for collaboration. The single Rakeﬁle expresses your intent much more clearly.

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No more .xcodeproj bullshit. The project structure is simpler and neater, better for collaboration. The single Rakeﬁle expresses your intent much more clearly.

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RubyMotion Costs

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Your own tools aren’t likely as good at Cocoa as Xcode. Not yet, anyway.

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I’ve spent a lot more time looking up docs in Dash.

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It's not a magic bullet. You still have to learn iOS APIs.

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RubyMotion Risks A major 3rd party dependency.

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No content

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The Future Ruby is a fantastic, enabling language. Will RubyMotion allow a "Rails" to evolve for iOS apps?

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Learning More Free screencast at The Pragmatic Studio, RubyMotion example apps, List of known RubyMotion projects, Cocoa books and learning resources, Big Nerd Ranch examples.

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@timriley Thanks