RubyMotion allows iOS development using the Ruby language instead of Objective-C. It provides a command line toolchain and compiles Ruby code to native iOS apps. While the syntax is Ruby, the underlying classes and objects are still Objective-C/Cocoa. This allows tapping into the full iOS SDK while enjoying Ruby's more succinct syntax. The document provides an example Hello World app and demonstrates how to load images from the camera library using RubyMotion and related libraries like Bubblewrap and RMQ.

1. iOS Development
with RubyMotion

2. Kieran Johnson
@kieranj

3. https://www.invisiblelines.com

5. What is RubyMotion?

6. Why Use RubyMotion?
No Xcode (unless that's what you want)
Command line toolchain ­ Rake
Less boilerplate
More succinct code
REPL for working with your app live
Native performance (compiles to bytecode)

7. No More Objective-C?
Objective­C
NSString *list = [NSString alloc] initWithString: @"Karin, Carrie, David"];
NSArray *listItems = [list componentsSeparatedByString:@", "];
[list stringByReplacingOccurrencesOfString:@", " withString:@" - "]
Ruby
list = 'Karin, Carrie, David'
list_items = list.split(', ')
list.gsub!(/, /, ' - ')

8. RubyMotion classes, methods
and objects are Objective­C
classes methods and objects

9. [].class
# => Array
[].class.ancestors
# => [Array, NSMutableArray, NSArray, Enumerable, NSObject, Kernel]

10. Syntax
[string drawAtPoint:point, withAttributes:attributes]
string.drawAtPoint(point, withAttributes: attributes)
string.send('drawAtPoint:withAttributes', point, attributes)

11. Method Overloading
def tableView(table_view, cellForRowAtIndexPath: indexPath)
# ...
end
def tableView(tableView, heightForRowAtIndexPath: indexPath)
# ...
end

12. REPL

13. Common Pitfalls

14. There's No Escaping
Cocoa/CocoaTouch

15. No Standard Library

16. No Require

17. Metaprogramming
No :eval or access to bindings
But :send, :method_missing, :define_method,
:instance_eval, :class_eval etc are all present

18. Examples

19. AppDelegate.m
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
CGRect frame = CGRectMake(20, 50, 280, 50);
UILabel *label = [[UILabel alloc] init];
label.text = @"Hello World";
label.textColor = [UIColor whiteColor];
label.frame = frame;
[self.window makeKeyAndVisible];
[self.window addSubView label];
return YES;
}

20. Creating an Application
$ motion create hello_world
Create hello_world
Create hello_world/.gitignore
Create hello_world/app/app_delegate.rb
Create hello_world/Gemfile
Create hello_world/Rakefile
Create hello_world/resources/Default-568h@2x.png
Create hello_world/resources/Default-667h@2x.png
Create hello_world/resources/Default-736h@3x.png
Create hello_world/spec/main_spec.rb

21. app_delegate.rb
class AppDelegate
def application(application, didFinishLaunchingWithOptions:launchOptions)
@window = UIWindow.alloc.initWithFrame(UIScreen.mainScreen.bounds)
label = UILabel.new
label.text = "Hello World"
label.textColor = UIColor.whiteColor
label.frame = [[20, 50], [280, 50]]
@window.addSubview(label)
@window.makeKeyAndVisible
true
end
end

22. Running an Application

23. Beyond HelloWorld

24. class CameraController < UIViewController
def viewDidLoad
view.backgroundColor = UIColor.underPageBackgroundColor
@picker = UIImagePickerController.alloc.init
@picker.delegate = self
@picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum
@picker.setMediaTypes([KUTTypeImage])
load_buttons
end
def load_buttons
btn = UIButton.buttonWithType(UIButtonTypeRoundedRect)
btn.frame = [[50, 20], [200, 50]]
btn.setTitle('Select an image', forState:UIControlStateNormal)
btn.addTarget(self, action: :select_image, forControlEvents:UIControlEventTouchUpInside
view.addSubview(btn)
end
def select_image
self.presentModalViewController(@picker, animated: true)
end
def imagePickerController(picker, didFinishPickingMediaWithInfo: info)
dismissModalViewControllerAnimated(true)
image_view = UIImageView.alloc.initWithImage(info.valueForKey("UIImagePickerControllerOr
image_view.frame = [[50, 200], [200, 180]]
view.addSubview(image_view)
end
end

25. Bubblewrap and RMQ
class CameraController < UIViewController
def viewDidLoad
view.backgroundColor = UIColor.underPageBackgroundColor
load_buttons
end
def load_buttons
btn = UIButton.buttonWithType(UIButtonTypeRoundedRect)
btn.setTitle('Select an image', forState: UIControlStateNormal)
btn = rmq.append(btn).layout(l: 50, t: 20, w: 200, h: 50)
btn.on(:tap) { select_image }
end
def select_image
BW::Device.camera.any.picture(media_types: [:image]) do |result|
image_view = UIImageView.alloc.initWithImage(result[:original_image])
rmq.append(image_view).layout(l: 50, t: 200, w: 200, h: 180)
end
end
end

26. Libraries
Bubblewrap
Sugarcube
TeaCup
Motionkit
RMQ
Promotion
RedPotion

27. Thanks!