By adding IMvxModalTouchView to MyView, let the view become modal. But, I cannot change it at runtime. i.e. MyView must be modal every time. Is it possible to make it more flexible, let say, Show(MvxShowViewModelRequest view, bool isModal); ?
This area of MvvmCross is called "preesentation"
Other Mvvm frameworks may refer to it as "INavigationService"
Within MvvmCross, the presenter on each platform is 100% overrideable. Some examples and source code links are provided on http://slodge.blogspot.co.uk/2013/06/presenter-roundup.html
If you want to implement some custom navigation hint, then:
all ShowViewModel calls have an presentationHint parameter - https://github.com/MvvmCross/MvvmCross/blob/v3.1/Cirrious/Cirrious.MvvmCross/ViewModels/MvxNavigatingObject.cs#L40
the presenters receive these hints in the PresentationValues property of the MvxViewModelRequest in the Show call
Related
In my Windows Store XAML app I’m using the TreeView control from the WinRTXamlToolkit and I’m attempting to two-way bind the SelectedItem property to a property on a ViewModel.
Out of the box, the SelectedItem property is read only and this makes sense because the control supports Virtualization.
I have seen some folk work around this with things like attached properties, helper methods and so forth, a great example of which is seen in this question
WPF MVVM TreeView SelectedItem
But all of the questions/solutions are not based on WinRT and all of my attempts to rework the solution code for a WinRT app have proven fruitless.
So, my question is, is this possible in a WinRT app? What am I missing?
Thanks
I'd skip trying to come up with a bindable property globally for the view model and instead use the IsSelectedBindingPath and IsExpandedBindingPath properties of the TreeView as in the debugging tools' example of the control's usage. Then when you want to select/expand an item from the view model - use a method similar to SelectItem() in my view model where I essentially set IsExpanded/IsSelected to true in item/node view models throughout the path from the root of the view model tree and load the content of the tree if the nodes in the expected path do not exist.
Does anyone have a simple C# Example showing how you could use Custom Container ViewControllers with Xamarin / Monotouch as per this Apple documentation -
http://developer.apple.com/library/ios/#featuredarticles/ViewControllerPGforiPhoneOS/CreatingCustomContainerViewControllers/CreatingCustomContainerViewControllers.html
Instead of posting question, thought would be more helpful to go away and create an example.
https://github.com/wickedw/ViewControllerContainer/blob/master/README.md
Readme Excerpt
I got to a point within a project whereby I wanted to display 3 different "Screens" of information based on a user selection.
The TabBarController was not appropriate as the GUI sat within a UINavigationController hierarchy. Yet, the UISegmentedControl fitted the design well.
I already had my views fully coded as seperate ViewControllers (and not all using the same creation pattern, some used Monotouch Dialog, others Nib files, others Programmatic).
Therefore, I did not want to rewrite existing code to use a Single ViewController controlling multiple Views.
I also thought it was time I looked at "Custom ViewController Containers" as they seemed an ideal fit for this scenario.
I'm just getting into my first project with (the unbelieveably excellent) MVVMCross and I can't figure out how to do something that seems fairly basic: composite views.
Suppose I've got a Person (FirstName, LastName, etc), and a person has an Address (Street, City, PostalCode, etc.). So I'll also have a PersonViewModel and an AddressViewModel.
This is a strictly tablet based app (iPad only, actually) and I want to use containment to have the PersonView contain the (reusable) AddressView, such that the outer (person) view binds to Person, while the inner (address) view binds to Person.Address.
I (dimly) understand the presenter concept for showing the views, as discussed here, but I can't see how to handle the propagation of changes from Person to Address and back.
Suppose the Person object has an Address object, but the PersonViewModel shows the AddressViewModel in an AddressView by passing some sort of Address id and rehydrating. Then the AddressView is binding to a different Address object than the one the Person contains. I don't see how to keep the two in sync, which of course would defeat the whole purpose of binding.
How should I do what I'm trying to do?
This is a really wide topic...
...and there are lots of possible answers.
I think it's important to consider ViewModel's as a very simple concept - I'd like to encourage you to think of ViewModels just as being models for views - definitely don't think of them as 'whole page' objects.
....
Within MvvmCross, you can use ShowViewModel and custom presenters to change the UI if you want to - and this is demonstrated in several MvvmCross examples including the split view presenter - http://slodge.blogspot.com/2013/05/n24-splitviewpresenter-n1-days-of.html
This ShowViewModel technique is really useful for navigation - for changing the whole page or for significant portions of it.
However, you don't have to use navigation paradigms if your app doesn't need them.
If you want to, then you can instead:
build your own hierarchies of viewmodels within the core
and you can then build your own databound hierarchies of views within the UIs
It's entirely up to you - your app is king.
....
I feel like I'm not explaining this very well...
....
So I gave up and recorded this video - maybe it helps: http://slodge.blogspot.co.uk/2013/06/n32-truth-about-viewmodels-starring.html
The video and sample code only covers the iPad, but I hope it's easy(ish) to see how you would extend it to other platforms:
for Windows you can use UserControl
for Android you can use MvxFrameControl, custom view or Fragment code.
There's a plugin that allows Control navigation in addition to the default Views navigation, hope it helps: https://github.com/ChristianRuiz/MvvmCross-ControlsNavigation
Please check out this implementation of a custom presenter for MvvmCross projects. To support Fragments in android and also multiple fragments into one other fragment/activity:
https://github.com/JelleDamen/CustomMvxAndroidPresenter
Suppose I have a setting in NSuserdefaults that should affect a property for a lot (but not all) UIView objects, for example the font size.
The setting can also be changed from a 'main' viewcontroller and should be 'distributed' to UILabel objects that live in a UIView in a UITableviewcell inside a UITableView inside a UINavigationController inside a UISplitviewController and so on...
If I create this property on all levels of the controller and view hierarchy, and set the property when the property in the parent is set, this costs a lot of code.
Apple seems to prefer this pattern to manage the managedObjectContext by handing it to the child controller along the chain.
But this seems like overkill. Lot of code is just for passing around the value of the property, while nothing is done with it. I do however use this pattern to set properties in all subviews of a view at once (by recursively walking through all subviews).
Delegation seems to be just as bad, except maybe not if the delegate would be top level parent view controller. But then I would be passing the delegate around to all child view controllers.
Should I go with Notifications instead? I already have a controller listening to (all) changes in the NSUserDefaults via the NSUserDefaultsDidChangeNotification. Should that controller post a specific notification when my setting is changed? In that case, who should listen to it? Should it be the view controller that is responsible for the views involved?
After some more reading, I found advise in the book Cocoa Design Patterns from Buck / Yacktman, as they state:
As a general rule, use notifications when there are potentially many objects that may observe the notification. Use delegates when exactly one object is given an opportunity to influence or react to changes as they are happening.
So notifications is the answer.
How can I use an IComponentActivator instance for a component, not just specifying a type.
That is, instead of
Component.For<XYZ>.Activator<MyComponentActivator>();
I want to be able say
Component.For<XYZ>.Activator(new MyComponentActivator(someImportantRuntimeInfo));
Also, is there a way I can choose an activator dynamically for a non specifically registered component? That is, I want to have an activator that looks at the type being resolved, decides if it can activate it, and if not, responsibility for activation should be passed on to the default activator.
So basically I want a global IComponentActivator that has the following logic:
Create(Type type){
if (ShouldActivate(type)){
DoActivate(type);
}
else{
// do default activation here somehow
}
}
Thanks!
EDIT
Just use ILazyComponentLoader
Activators are instantiated by the container, and there is no way to provide instances OOTB.
If you really want to do this, I'd say you can extend the container itself.
Put your custom instace activators in ExtendedProperties of your component under a well-known key
inherit from DefaultKernel
Override CreateComponentActivator method
In there return the activator from ExtendedProperties of the component
There's no way to create global activator. You can add IContributeComponentModelCreation implementation that switches the activator to some custom one wen creating your component if you really want to.
But the most important question is this:
What are you trying to achieve by
this? Why do you want to do this in
the first place?