I have a custom view that's a bit of a hack. Basically it's a UIView with tableView as it's property, with additional views in the tableView that need their own delegates. I need a viewController for the UITableView and can't make the UIView it's delegate according to this SO link Custom UIView as UITableView delegate and datasource?.
Can I make the UITableView have a property of UIViewController and set that UIViewController as the tableView's delegate?
In this case according to OOP, the UITableView has a UIViewController so technically, I could expect this to work. But, I am wondering if down the line somewhere this could create problems since the UITableView and UIViewController are coupled in this way.
You don't need a UIViewController for the UITableView - you just need an object or objects that implement the data source and a delegate protocols. As per the accepted answer on the question you linked to you can use a separate controller class to provide this.
The right answer depends a little on how the table is used with your UIView subclass.
If the table will always have the same content (Say a list of months) and there is no value in exposing or abstracting the properties then you can code the delegate and dataSource inside your UIView subclass or in an assistant class.
If the table content will vary depending on how the UIView is used (say a list of people where you don't know what the list is - friends, relatives, employees...) then it would make sense to simply expose the tableview's datasource (and delegate if necessary) properties via your UIView subclass
Related
I'm learning Swift. Sometimes I see that Main.Storyboard is used to set up the tableView delegate and dataSource (ctrl+click and so on). Sometimes I see that it's done through coding instead like so:
// create the variable for the tableview
IBOutlet weak var someTableView : UITableView!
// setup delegate and datasource
sefl.someTableView.delegate = self
self.someTableView.datasource = self
I do understand how it works with second way. But it's difficult to realize how it works through Main.Storyboard with no IBOutlet setup.
Thank you for your responses!
It works exactly the same way :)
Let me refresh the principle:
You have a class, provided by Apple in this case, that has to work for a lot of scenario. Apple decided to use a kind of inversion of control, called delegation, where the workflow is inverted (hence the name) : instead of the view controller giving order to the tableView by calling methods on it, it is the tableView that goes and fetch its orders from the controller by calling methods on it.
In order to achieve this kind of IoC (inversion of control), the TableView MUST know the "address" of the object it has to ask for its order. Like you have to know your boss' email address to ask him stuff. So, the UITableView class as a property called dataSource that means to store that address.
Now as a ViewController programmer, you have to set this property to be the address of the view controller that will give the order to that tableview.
2 ways of doing it :
in code : in the view controller, you have a property pointing to the tableview (if linked from the storyboard, it is called indeed an IBOutlet, but doesn't have to be) and you set it's delegate property to self. (meaning 'hey tableView, your boss is myself)
Or you do it in the storyboard, because the graphic template for the tableView let you ctrl+drag from the tableView to the ViewController and set the datasource connection. In this case it will be the storyboard who will have to find the address of the tableView (since it is the one creating it, it's kinda easy) and setting it's delegate property to be the address of the view controller (meaning hey tableView, your boss will be this guy)
Either way, the viewController has to be ready to answer all the question from the TableView, so conforming to the UITableViewDataSource protocol.
the delegate scenario is the same.
It is important to understand how the loading of views works in iOS. Your xib will be translated into the hierarchy of views and they are loaded onto the memory. When you make an IBOutlet of those views, you'll have a reference of that loaded view in your code. If you do not create an IBOutlet, it doesn't mean that the view isn't there. It is there and it is in the memory.
When you set the delegate and the dataSource of a tableView and when the tableView is loaded onto the memory, it sets the delegate and the dataSource of the loaded tableView to the class as specified by you. It doesn't matter if you do not have a reference to it.
I want to create a UITableView in UIView class. Can I? The UITable is nested in the UIView, so I figured, I should put the code of the the table in my custom UIView class, but on the other hand, usually the UIViewController is responsible for the table delegates. So what is best?
UITableView has a data source and a delegate which need to be implemented. These could be implemented separately in different objects or they could be implemented in the same object.
Many times, the UIViewController is used as the data source and delegate object but it's not required. Since you're adding the UITableView to a custom UIView it makes sense create a custom object to handle the data source and delegate.
It's fine to add a UITableView to a custom UIView which is not the UIViewController's view.
What I have: 10+ view controllers using a UITableView with custom UITableViewCell. Each view controllers load different data and forward to different sub-pages, thus they cannot combine together.
The aim of the change is to centralize the management of table view's look & feel in a single custom UITableView subclass. But since the data loaded by each view controller is different, I think the UITableViewDataSource and UITableViewDelegate have to be assigned to its original view controller class.
How do I make the change? Or I am thinking at wrong direction?
A tableview's datasource can be separate and independent from its delegate. So, put all of your appearance configurations in a UITableView subclass that implements its own delegate methods, and then create a separate NSObject subclass for each tableview that is responsible for the datasource implementation.
You could make a superclass for all your view controllers that collects all the common logic.
In the Object Library of Xcode, there are two options one can use to create table view - table view and table view controller.
What is the difference between the two and when would they be used ?
A TableViewController is a ViewController with a TableView built in. This will have the delegate methods needed already declared and setup. This VC is already a TableView delegate and datasource. It cannot be resized. Upside is ease of use, downside is very limited flexibility.
A TableView is just that a TableView (subclass of UIView). It can be added to a ViewController and resized, used alongside another view based object, etc. The upside is the flexibility, the downside is that you have to setup the delegate and datasource methods yourself (in my opinion, well worth the time to get the flexibility).
One other note is that when using the new Static TableView cells (part of iOS5), you have to use a TableViewController.
The UITableViewController is a subclass of the UIViewController. It already assumes you will have UITableView as your rootView, so you already have access from the code to a tableView (self.tableView). It implements the UITableViewDataSource and the UITableViewDelegate protocol. It also gives you alot of methods for you to override. It allows you to not depend on XIB file, because you already know what you will have (UITableView as a rootView).
The UITableView is just UIView, normally you will have to comply to the protocols I have referenced above in your UIViewController in order to populate (data source) and work with it (delegate), and you probably have to create an IBOutlet for your UITableView.
On one hand you have speed but you are not as flexible as the other path. On the other you have the opposite.
I've got a UITableViewController that inserts custom UITableViewCells into a UITableView. Is there a way that I can put this UITableController/View combo into different views? I've got the behavior of the UITableView acting the way I want, I just want to use that UITableView in different UIViews (say a UIView with a UILabel above the UITableView and one with a UILabel below the UITableView).
I know I can make a UIViewController that has an embedded UITableView in it and have the UIViewController act as the UITableView's delegate, but then I would have code reuse (the UITableViewController logic would be in multiple UIViewControllers). Or am I looking at this problem the wrong way?
I want to somehow reuse the functionality of my UITableView in different UIViews.
Thanks
Yes, you can, simply instantiate (or get a reference to) the UITableViewController inside the UIViewController and call something like this:
[self.view addSubview:tableViewController.tableView];