A mini Mvvm for Xamarin.Forms

BaseViewModel.cs

    public abstract class BaseViewModel : INotifyPropertyChanged 
    {
        public event PropertyChangedEventHandler PropertyChanged;
     
        public virtual void ReverseInit(object value) { }
        
        protected void PushViewModel<T> () where T : BaseViewModel
        {
        	PushViewModel<T> (null);
        }
        
        public static Page ResolveViewModel<T>(Dictionary<string, string> data)
            where T : BaseViewModel
        {
            var viewModel = IOC.Current.Resolve<T>();
        
            return ResolveViewModel<T>(data, viewModel);
        }
        
        public static Page ResolveViewModel<T>(Dictionary<string, string> data, BaseViewModel viewModel)
            where T : BaseViewModel
        {
            var name = typeof(T).Name.Replace ("Model", string.Empty);
            var pageType = Type.GetType ("App.Pages." + name);
            var page = (Page)IOC.Current.Resolve (pageType);
        
            page.BindingContext = viewModel;
        
            var initMethod = TinyIoC.TypeExtensions.GetMethod (typeof(T), "Init");
            if (initMethod != null) {
                if (initMethod.GetParameters ().Length > 0) 
                {
                    if (data == null)
                        data = new Dictionary<string, string> ();
        
                    initMethod.Invoke (viewModel, new object[] { data });
                }
                else 
                    initMethod.Invoke (viewModel, null);
            }
        
            var vmProperty = TinyIoC.TypeExtensions.GetProperty(pageType, "ViewModel");
            if (vmProperty != null)
                vmProperty.SetValue (page, viewModel);
        
            var vmPageBindingContext = TinyIoC.TypeExtensions.GetProperty(pageType, "BindingContext");
            if (vmPageBindingContext != null)
                vmPageBindingContext.SetValue (page, viewModel);
        
            var initMethodPage = TinyIoC.TypeExtensions.GetMethod (pageType, "Init"); 
            if (initMethodPage != null)
                initMethodPage.Invoke (page, null);
        
            return page;
        }
        
        protected void PushViewModel<T> (Dictionary<string, string> data) where T : BaseViewModel
        {
            BaseViewModel viewModel = IOC.Current.Resolve<T>();;
        
            var page = ResolveViewModel<T> (data, viewModel);
        
            viewModel.PreviousViewModel = this;
        
        	ITabbedNavigation tabbedNav = IOC.Current.Resolve<ITabbedNavigation> ();
            tabbedNav.PushView (viewModel, page);
        }
        
        protected void PopViewModel()
        {
        	ITabbedNavigation tabbedNav = IOC.Current.Resolve<ITabbedNavigation> ();
        	tabbedNav.PopView ();
        }
        
        protected void PopViewModel(object data)
        {
        	if (PreviousViewModel != null && data != null) {
                var initMethod = PreviousViewModel.GetType().GetRuntimeMethod ("ReverseInit", new Type[] { PreviousViewModel.GetType() });
        		if (initMethod != null) {
        			initMethod.Invoke (PreviousViewModel, new object[] { data });
        		}
        	}
        	ITabbedNavigation tabbedNav = IOC.Current.Resolve<ITabbedNavigation> ();
        	tabbedNav.PopView ();
        }
        
        protected void RaisePropertyChanged([CallerMemberName] string propertyName = null)
        {
        	var handler = PropertyChanged;
        	if (handler != null)
        	{
        		handler(this, new PropertyChangedEventArgs(propertyName));
        	}
        }
    }