As the title states, I'm looking to simply pass the information.
I have a tabbed view application currently, and the user inputs data into a text field, presses a button, then labels are filled with the entered text on the same viewcontroller.
I want to send that information to the other tab and fill a label.
I know I can do this via protocol or segues, however, I want to remain on the current tab. I haven't seen this as an example anywhere, only to switch the view to the other screen.
Anyone know how to simply pass the string entered and not change the view?
You are looking at this all wrong. You do not want or need to pass data between view controllers. If your app makes proper use of MVC (model, view, controller), then what you should be doing is updating a model. That model should broadcast that is has been updated. Anyone that cares about the model should react to those notifications as needed.
You have a tab controller with multiple view controllers. Two or more of your view controllers have an interest in the same data model. Both should reference the same instance of the data and be setup to be notified about changes to that instance of the data model.
One view controller, through its views, updates the data model. The data model then sends out a notification that is has been updated. Now the interested view controllers receive this notification and update their own views based on the updated data model.
No view transitions required. No segues required. No communication between different view controllers required.
Look at the documentation for NotificationCenter for ways to broadcast messages and for ways to listen for such messages.
Related
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.
In my new Swift app I am using a slide side menu with SWRevealViewcontroller.
On the rear view controller there are several fetch requests to retrieve the number of core data objects that meet some conditions. On the front view controller, the app user can create new core data objects.
In the normal way of using the app, the app user creates or modified the core data objects, and later he/she can reveal the rear view controller to see the number of objects of each type.
Please take a look of the two view controllers:
Front view controller:
If the user taps on the +button, a new object is created.
if the user taps on the menu button, the rear view controller is shown, as you may see in the image:
And now, finally my question: As you may see in the image, both view controllers are loaded and showed. I want to know if it is possible that on this scenario, with both view controllers on screen, if the +button is tapped on the right view controller, could I implement a way to perform the fetch requests on the left view controller to update the count of the objects of each type?
I have solved it using a NSTimer on the rear view controller. I guess this is not the best solution, but it works. If the user taps on the +button to create a new object, the timer launches the fetch request to update the number of objects from each type.
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"
Can anyone tell me how to maintain the state of a view even while navigating through different views. I have a main view controller that has some button interaction and label changes with those interactions and I want to maintain those states while the user navigates to different pages.
It is not a good idea to "save" ui object, it is instead better to save the data you want to use somewhere (like a file) and get it when needed
Im making a messaging app that works like most messaging apps so that you can view multiple conversations by looking at a table view made up of cells containing the person or group you are messaging. The problem I am running into is how to generate another view controller for when you select the conversation you wish to enter. How do you do this? Do you generate a separate view controller for each cell? OR Do you make a template view controller that grabs the conversation and user information from the backend and enters it into that template view controller?
I can not find this on the internet nor a github ios messaging project that is updated enough to actually work in xcode. If somebody could help me out with this then that would be great! Thanks!
There are a lot of different ways to do this, but each cell in your messaging app's main view should have some reference tied to it knowing what conversation it is, you can make a UITableViewCell subclass that has a messageID property of some sort. Then, in didSelectRowAtIndexPath in your main view, grab the cell's messageID value and pass it to a UITableViewController and push it. In viewDidLoad of your UITableViewController, you will do your logic to retrieve the data for message thread and then display everything accordingly.
A typical way to do this is have a UIViewController subclass for displaying a conversation. When the user selects a conversation from the list, you select the appropriate model that represents this conversation and create a new conversation view controller that will display the contents.