I have a tableview where a single prototype cell is used only 3 times. This cell has some buttons on it that trigger displaying and hiding content within the cell.
I could reuse the cells, but that requires a lot of resetting each cell so that if I expand A's content, B's content isn't expanded when it loads. Furthermore, this requires me to keep a state record in the Controller class, where I would prefer to have this all handled by the Cell itself for modularity. In other words, the amount of work to keep each cell in the correct stage seems inefficient.
What would be the best way to go about this? Do I use static cells? Is there a way to instance 3 separate cells of the same type and place them in the TableView?
You certainly can have the modular part of the code you need inside the cell itself. If you don't want to reuse the cells, then add a custom initializer with a case for each cell type. Inside your delegate method cellForRow:
return CustomCell(type: .myCustomType)
If you do it this way, you can add a switch inside the cell's initializer & set up the cells according to their types that way. And i'm assuming by "static" you mean just three instances. You "add" cells to the table by telling the delegate the number of cells that it will need, which will in turn call cellForRow x times.
Related
I have a UIViewController with a collectionView inside it. The layout may seem confusing but I am making use of horizontal scrolling UICollectionViewCells, presented in 3 sections.
The main collection view is made up of 3 sections. I access 3 different UICollectionViewCell classes for each section becuase it is fetching different data for each one. Once the data is fetched, it dequeues another Cell class, which is the same one accessed for all the sections.
There are 2 buttons in each cell. When I press the button, a value changes within the database. When I re-run the program, the cell in which the button was pressed has moved to its corresponding section that it should be in as per the change. However, I want to achieve this as soon as I press the button. How can I move the cell from one section to another, baring in mind that they the cells presented are inside a collectionview cell making up the sections, which is then inside a greater UICollectionView.?
I've tried researching how to do this but no luck, and everyone seems to be using a drag and drop method which seems too complicated for what I am trying to achieve. Would appreciate any help.
Thanks
The approach I followed to achieve the above situation is using a custom Delegation when cell is removing from collectionviews. A container CollectionView has two sections with 2 different cells containing two different Horizontal UICollectionViews. These two collectionview's cells have UIButtons. When tap on one collectionView's button, that particular cell is removed, custom Delegate method calls and another CollectionView's cell is populated. This is the link of the project I have created for this particular scenario. For better understanding, here is a GIF for demonstration.
I am making an iPhone app.
In this application I have to make a look like below.
I am not allowed to use collection view.
I am using tableview, and custom cells. Which I am easily able to incorporate. Means taking 3 subviews in Custom cells. And making a look.
Here the problem is In a cell, how do I distinguish each object. so that I can call each object, to set an image on image view.
Is there any Object oriented mechanism to distinguish all 3 objects in a cell ?
Try to get the data as NSArray of NSDictionary containing an array of 3 objects that you want to display on cell.
Assign tag to UImageView in the custom cell.
In cellForRowAtIndexPath, get the 3 objects and apply image using switch case.
Well everything depends on how you get the data from the server
You can use outlet collections which will give you an array of UIImageView and you can assign different tags to the imageview so you can assign to them.
You can use these guides to understand how outlet collections works:
http://nshipster.com/ibaction-iboutlet-iboutletcollection/
http://useyourloaf.com/blog/interface-builder-outlet-collections/
All the standard procedures should work to achieve this but then it only depends on how nice you want to do this.
The straight forward procedure is to expose the outlets of the image views and labels in the cell and assign the correct values to those when dequeuing/creating table view cell.
The first upgrade would be to rather expose 3 setters on the cell to simply set your model to each of them which will then internally set the images and texts inside the cell.
The next thing you may do is to rather insert an array of objects (always sending up to 3 in your case) instead of having 3 setters.
At this point you may actually rather use a collection view INSIDE the cell and make the cell a data source for the collection view. But this is totally optional.
Now since you may still dislike the table view data source you may create another model which contains an array of objects (again up to 3 in your case) and make a system that will distribute your original array of objects into the array of these containers.
If then you need to handle buttons or other touch events they may be handled with collection view delegate or 3 buttons and in both cases I advise you to handle those in the cell and create a custom delegate for the cell which will report the event with the appropriate model.
This together generates the following:
When you receive the data call a container class to distribute your array of objects (into groups of 3) and assign it to your table view data source (view controller usually)
Number of rows is the same as number of containers in the array
Cell for row assigns the container with row index to the cell. It assigns self as a delegate
Cell internally handles the object distribution either via collection view, separated outlets or outlet collections.
Cell handles actions and reports them back to the delegate (- (void)myCell:(MyCell *)cell selectedItem:(MyObject *)item;)
The cell delegate can again handle what to do upon reported actions
Also if you want to avoid a collection view inside the cell you can create a custom view using xib so you do not copy the labels, image views and such. Then simply create 3 of these custom views inside the cell. Also by using inspectable and designable these views will be visible inside the storyboard.
First I'll say that a restriction against using UICollectionView is silly. Are you still targeting ios5?
I'd look at it like this.
make your own view class for the 'subcell' let's use this term for any single instance of the 3 views per cell. I'd subclass UIImageView, adding the label for the name down the bottom and a 'setSelected:' kind of method to highlight when selected via user interaction by drawing differently.
make a UITableViewCell subclass to host and layout up to three of these subcells. I say up to 3 because the last cell may contain 1 or 2 subcells and not 3 if the total people to represent is not divisible by three.
Selection Logic: You'll need to override 'setSelected:' because you want to deselect and select only subcells, you don't want the whole cell to highlight on selection, only a third of it.
You'll also want to implement touchesEnded: in this cell so that you can figure out which of the three subcells was last touched, and you'll need to be able to query or communicate this back to the controller, probably using delegation. If the cell can communicate back whether selection was in subcell 0,1 or 2 then this together with the UITableViewDelegate didSelectAtIndexPath should map to your model nicely - selectedPerson = myArrayOfPeople[ (indexPath.row * 3) + subcellIndex ]
You'll be able to decorate your cells in cellForRowAtIndexPath: in similar fashion..
personOne = model.arrayOfPeople[indexPath.row*3]
personTwo = model.arrayOfPeople[indexPath.row*3 +1 ]
personThree = model.arrayOfPeople[indexPath.row*3 + 2 ]
I need to display a table with in my iPhone app:
neither the number of cells nor the contents are known at compile time, but only at run time.
Views for each cell may differ, one cell has textField and another may have some other view control.
Should I consider Static or prototype cells?
Should I consider tableViewController or viewController with tableview in it?
Any thing I need to consider before I start coding? Thanks in advance
For The issue of dynamic Number of cell at Run time, you can call reload data for table view at any time you have the data source ready.
Prototype Cells should be used with no problem.
Simple Table View will be sufficient for the task.
You have to make cell, either in code or in storyboard, for each type of cell you want, 1 table View can have multiple types of prototype cells, Just name them differently and then make the objects of only the specific cell of which the data is best suited.
It is not that difficult but do handle the data source with extreme care.
Should I consider Static or prototype cells?
If you know all possible subview combinations that your cells might need to display the data appropriately, and they are relatively few, make one prototype for each. for example:
One text field,
Two labels,
One image view and a label,
...etc.
Otherwise, just use the plain-vanilla UITableViewCell (no subclassing) and remove/add subviews at runtime when reusing them (that is, inside the method -tableView:cellForRowAtIndexPath:).
Should I consider tableViewController or viewController with tableview
in it?
The only reason I would choose UIViewController + UITableView over UITableViewController is if -for example- I needed the table view to only take up part of the main view's bounds/screen, and display some other subview in the remainder. Otherwise, you get so much "for free" with UITableViewController that there's just no point in implementing all of that from scratch.
You have to choose prototype cell, u can create different types of cell depending upon your requirement.Any think ok for u, u can create tableview controller or view controller.
I used to use static UITableView but the table is too long and overflow the memory.
I switched a dynamic prototype UITableView with 1 type of cell, which has an UISwitch in it.
One of the cell, when turning on the switch, will turn off the switch of another cell. These cells have fixed index.
The IBAction method is in my UITableViewCell subclass and I don't want to add the UITableView as a property in my UITableViewCell.
How do I achieve the above effect?
I'm planing to use an id or similar to distinguish between the cells as each cell's switch has different effects, that doesn't solve the above requirement.
Thanks,
I would add a block property to your cell which you can use to notify your controller of changes in the switch. See my answer below to a question on this:
How can I get index path of cell on switch change event in section based table view
All your logic can now be implemented in the view controller.
You are best to create a data model in the view controller which the cells simply provide views and controls onto. When you flick one switch and the block fires, update the data model and simply reload the table. Any cells affected will show the new data model positions for their switches. Avoid using one cell to adjust another. Just update the model and reload the cells.
I'm trying to figure out how to have a few static cells in addition to dynamic cells (I think) but when I start a new Master-Detail app and switch the default Dynamic Prototypes to Static Cells, it crashes.
I think, since I'm still new at this, that I don't understand how all of the components (table views, cells, delegates) are wired. After I switched to Static Cells I made three cells but they don't show up. The app just crashes.
I can include code but basically, I create a new Master-Detail, switch to Static Cells, change the name of three cells and it crashes (in the main loop).
Thanks ahead for everything.
If I understand your question, this is the explanation you are looking for:
Prototype (reusability):
When you use Dynamic cells, you use Prototype cells. That means either in IB or in your code, you create an instance of UITableViewCell, and give it an identifier (reuseIdentifier). The UITableView uses this prototype to generate as many cells (rows) as you need. UITableView create (and use memory) for as many cells as it needs to fill the screen. Once some of these cells go off the screen, UITableView reuses them -- recycles them.
You can define more than one prototype cell in a UITableView. The idea is that each prototype serves a different purpose. For example, you define a prototype cell that has only one big UILabel and its purpose is to use static text. You define another prototype that has only one UIImageView. It depends on your design and how you want to display your data.
To use prototype cells, in IB, you use Dynamic Prototypes cells, and set an identifier. Then you have to implement UITableViewDataSource methods, such as:
– tableView:numberOfRowsInSection:
– tableView:cellForRowAtIndexPath:
These methods are delegate methods of UITableView.
If not using IB, you would create cells in – tableView:cellForRowAtIndexPath: method:
UITableViewCell *cell = [[UITableViewCell alloc]
initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString
*)reuseIdentifier];
Static:
The idea of static cells is just simplicity. You can use the prototype cells (e.g. only one prototype) and feed in a static NSArray, for example, as data source. To take the task of implementing UITableViewDataSource methods, Apple introduced static cells, where you would only use the storyboard and IB. In IB, you select the table view, and choose Static Cells instead, and type in your text, or set the image.
You don't want to make any dynamic changes to static cells later when the app is running because it is not meant to, and you would have to implement many more methods that it is not worth it. Although it not much of a work to get the indexPath of the selected row, but the idea is if you need to push a new view from selection of a static cell, you would use segues, instead of implementing any code.
When using static cells, you should not implement UITableViewDataSource method, otherwise your app crashes, and vice versa, if you do not implement UITableViewDataSource methods (required ones) when using prototype cells, your app crashes.