I am creating a tab based application using MonoTouch and has a need to pass the data from one tab to another. For example - my default tab loads a list of articles and I need to have that list passed to another tab if user selects it.
At first I thought that I could populate the list in the first view controller and pass it to AppDelegate from where the second view controller can pick it up but that doesn't seem to work.
What is the best way pass data between tabs in iOS? I am looking for MonoTouch example as I am not much familiar with objective-C syntax.
If you are doing this in code rather than using InterfaceBuilder...
Make your own UITabBarController by inheiriting from it. Add your shared data items to that new class. Inherit from UIViewController to create xyzViewController. Add a contructor to this which passes in and stores a reference to your UITabBarController.
You can now ref the common data using the local UITabBarController reference.
If you are using InterfaceBuilder create all the classes and connect them up using outlets.
Related
I am making an app with swift and xcode. In it I have a model class with user's information in it. I want to display some of that information with one view controller, update/change that information in another, and keep all of the views up-to-date with whatever is in the model class.
I was told using a singleton could work but is not recommended. Is there a better, more accepted way of accessing the model class from multiple view controllers without a segue between them (I am using a tabBarViewController)?
If you want to go "pure" that is follow Apple Best practices where a View Controller is never hard-coded to a global model (more of a pain than is worth, practically, in my opinion):
Subclass UITabBarController to contain the model instance as a stored property (perhaps private(set) is the best access level here, but however you want to expose it safely to other classes -- PUBLICLY EXPOSED AS A PROTOCOL TYPE ONLY OF COURSE.)
Don't forget to set the identity class of your Storyboard Tab VC to this new subclass otherwise your sexy code will not run.
In your (hopefully base class to all child tab VCs) View Controller class, hook into didMoveToParentViewController(parent: UIViewController). Gently downcast (as?) to the UITabBar subclass above, and extract the model, and copy the reference into your local stored property. It will happen exactly at the right time, just as you land into the soft arms of your parent VC.
Happiness!
You can try KVO mechanism. By which if you change a model variable's value that will reflect in another controller. For your reference
https://www.appcoda.com/understanding-key-value-observing-coding/
I am trying to create an app for iOS using Swift but running into problems with the very basics.
To keep it simple I just want the app to initially be a single view application with a button and some sort of list view on the page. I believe a TableView is what is recommended here. When I click the button, I just want it to populate the list/table view with some entries, that's it. To start with, I don't care if these entries are hard-coded, I just want to get something working.
I have been looking at different samples but I am getting confused. Some of them seem to suggest using a TableViewController others don't. When I use a tableview controller, the UI I had created seems to get completely replaced with just an empty tableview list and the button is gone.
I previously have developed apps in Windows phone and found it a lot easier. I'd just add a listview object and in the click method of button, add the items programmatically etc. But this is my first time trying to create an iOS app and it seems a lot more confusing. There are delegates, controllers, views all seemingly needed in order to do something very simple.
Can anyone give me some basic step by step instructions about how to add a tableview to an application and load some data into it through a button click?
Make sure you are clear about the difference between a view and a view controller.
iOS uses the MVC design pattern (Model View Controller).
A view object displays contents to the user and responds to user interaction.
A model object stores state data.
A controller object drives the app logic and mediates between the model and the view.
A UITableViewController is a special subclass of a UIViewController who's job is to manage a table view. It has some extra support in it that makes it a good choice for managing a table view, BUT... there is one annoying thing about it. It is designed so the ONLY view it can manage is a table view. You can't use a UITableViewController if you want to add buttons, labels, and other UI elements to your screen outside of the table view.
What I usually do is to create a create a table view controller, create a separate regular view controller, add a container view to the regular view controller, and then use an embed segue to embed the table view controller inside the view controller. (you just control-drag from the container view to the table view controller.) That way you get the best of both worlds. You may want to create a protocol that the table view controller would use to communicate with it's parent view controller.
You should be able to find a tutorial online on setting up a table view controller as a child of another view controller using container views and embed segues. It's quite easy.
I have a songs = [Song]() array of song objects being generated in the first view controller of my tab bar.
How can i use this array in the other view controllers of the UITabBarController?
I need to show this in my initial view controller, a table containing all songs, but also need to use this data in a second view controller, a table containing only favourite songs.
I think a good solution would be to create another class for managing the songs data. Basically, you want to add a model for your view controller to look at. In this new class, you may decide you want to use a singleton to provide the exact same data to every object viewing the data. This is similar to what core data does, and is something I think you should consider using (core data works with xml). But, by having a class other than your view controller manage your data, any view controller (or any other object) that needs access to the data need only ask the data class for it.
I am trying to develop a Table View Controller(having a navigation controller),where rows are connected to multiple View Controllers (TextField,TextView,TableView,DatePicker,ImageView etc.).
So I design like this,if I click on any row,it should open one UIViewController having container view and then place the appropriate controller in the container.All the same type of tableview rows are using same View Controller as a child view of the container.
I am able to place proper view controller(example - 1.TextViewController for Text View
2. Table View Controller for Table view 3. DatePickerController for Date Picker.) in the container depend on their the row type.
But I am little bit confuse about how to pick the data from the child view when I click the done button(2nd screen right top). i.e for child Text Field I have to pick the input data whatever I type in the input box. For child Table view I hide the done button,so as soon as user select the data 'cellForRowAtIndexPath' should get fire and pass the seleted data.
How to do that data handleing? where to write that?
Is there any other way to design this?
As #Suhail mentioned the best way to do it, in general, when you want to pass data from a child view controller to the parent view controller, or in some cases from a controller to previous displayed controllers (that are still in the stack), is by using delegate pattern. You can implement delegate pattern with iOS protocols or with blocks. In my opinion, both approaches have their pros and cons, for that topic you'll have to do little more google search since this is not the place to discuss it.
Let's define some cases for your case(not all the cases):
You want to send data from ChildTableViewControler to Field controller (screen 3 to screen 2)
In this case, from what I understood, both controllers are embedded in a parent controller, so you'll have to set parent to be the delegate to the two child controllers. You have to create one or two protocols depending on your actions or data you want to send to the controllers. Create a property called delegate (you can choose your own name) on each of the children, implement the methods on the parent view controller, whenever you add one of the children on screen, set the delegate property to be the parent view controller. Now whenever you want to send data to the other child, you'll have to call the methods declared in your protocols. Remember, you have access from the parent to both children via childViewControllers propery.
Short version: One/Two protocols for children, parent implements the protocol(s) and responds to child action.
You want to send data from Filed to TableViewController (from screen 2 to screen 1)
In this case you'll declare a protocol in the parent view controller, which will be implemented by the TableViewController.Declare a delegate (or whatever name you like) property in the parent view controller. When you add the Filed controller on screen, you set the delegate property to be the TableViewController. Now you can communicate with the TableViewController from the Field controller via delegate property.
Short version: one protocol in parent view controller, TableViewController implements the protocol and responds to TableViewController actions.
You want to send data from ChildTableViewController to TableViewController (screen 3 to screen 1).
This is the same as case 2.
One of my rule when I send data from view controllers is something like this: if I want to send data forward (to the next screen that will be displayed) then I use property/methods. If I want to send data backwards(to previously displayed controllers) then I use delegate/blocks.
And my last advice, please check the delegate/blocks implementations and how to use them before you start implementing one of the above solutions. You can have lots of troubles if you implement them wrong, especially memory issues and random crashes.
A little bit off topic, if the reader of my answer is a 9gagger then "sorry for the long post, here's a potato"
In my application I created a container view(called ContainerViewController) on the top of an another view(called GameViewController,where I keep the game logic and api callbacks).I also have other views and an api class.My container view contains 3 views and I am trying to pass some objects to one of my container view(VC1). Since GameViewController is only connected to ContainerViewController(meaning there is no segue directly, so I can't use prepareforsegue and I can't use presentViewController, since they childViewControllers), I can't pass data.
I also tried just getting the values from my deserializer class(inside vc1). The problem with that was the VC1 gets called before.
my question is, how can I set values of VC1 from my callback inside the GameViewController?
This is what my storyboard looks like:
Thank you.
You can do it many ways:
1st way : You can pass the data using Notification.
2nd way : You can create a separate singleton data model class to store your game data. Then you can access the object of that class among your view controllers to set the properties in view controllers.