A domain specific language (DSL) for easy use of key-value-observing (KVO) in RubyMotion projects.
If you'd like to learn more about the KVO mechanism on iOS and Mac, take a look at the Key-Value Observing Programming Guide by Apple.
Note: Although the classes of the UIKit framework generally do not support KVO, you can still implement it
in the custom objects of your application, including custom views.
Add motion-kvo as a git submodule of your RubyMotion project:
git clone https://github.com/dreimannzelt/motion-kvo.git vendor/motion-kvo
Add the motion-kvo lib path to your project 'Rakefile'
Motion::Project::App.setup do |app|
app.name = 'MyApp'
app.files.unshift(Dir.glob(File.join(app.project_dir, 'vendor/motion-kvo/lib/**/*.rb')))
endNow you can start to add the helper methods to every class you like:
class ExampleViewController < UIViewController
include Dreimannzelt::KVO
...
endTo observe a key path of a target you do:
class ExampleViewController < UIViewController
include Dreimannzelt::KVO
def viewDidLoad
@label = create_ui_label()
observe(@label, "text") do |old_value, new_value|
puts "Changed #{old_value} to #{new_value}"
end
end
endIt's possible to add more than one block to the same key path:
class ExampleViewController < UIViewController
include Dreimannzelt::KVO
def viewDidLoad
@label = create_ui_label()
observe(@label, "text") do |old_value, new_value|
puts "Hello from viewDidLoad!"
end
end
def viewDidAppear(animated)
observe(@label, "text") do |old_value, new_value|
puts "Hello from viewDidAppear!"
end
end
endYou can also observe collections (WORK IN PROGRESS):
class ExampleViewController < UIViewController
include Dreimannzelt::KVO
attr_accessor :items
def viewDidLoad
@table_view = create_ui_table_view()
@items = [ ]
observe(self, "items") do |old_value, new_value, indexes|
@table.reloadData
end
end
endYou are responsible to unregister observers properly. You can unregister one observer:
class ExampleViewController < UIViewController
include Dreimannzelt::KVO
...
def viewWillDisappear(animated)
unobserve(@label, "text")
end
endor all at once:
class ExampleViewController < UIViewController
include Dreimannzelt::KVO
...
def viewWillDisappear(animated)
unobserve_all
end
endmotion-kvo is released under the MIT license: