Are there any use cases where one would better use UIScrollView instead of one of its two subclasses UICollectionView and UITableView?
I saw one used in a piece of recent code and cannot think of any justifiable reason to use it instead of, in that case, a collection view.
Related
I have a working UITableViewCell. Now I have a different cell I need to make which is exactly like the previous one - but has a UIWebView instead of UIImageView.
I was thinking of doing a different xib for the cell, but the thing is they have tons of code and logic in common (for the rest of the controls)
What is my best approach in this case?
You can make a parent class: put all the common code there, then make 2 subClasses of this superClass, they'll inherit the superClass code, and put there all the code and objects specific for each of them
I would like to know how to handle, for my iOS app, the following situation:
I have to deal with something like this (basicly this is an article with comments, received from a server):
=- Text and Images -=
=- UIWebView -=
=- List of Comments -=
Now, I came up with two solutions:
Have the content above the list of comments wrapped in a UIScrollView, and create Views for each and everyone of the comments (don't know many of them could be), and
Make the list of comments a UITableView, and the above content its Header.
Which of these (or possibly another if you have any recommandations) should I choose? It may look not very important, but I would like to know this, so I could use the idea in further developing.
I would use a UITableView with a custom UITableViewCell wich holds the comments.
It will definitely have a better performance the UITableView than the UIScrollView since the UITableView re-uses the cells.
Using a UITableView you will just have to worry about customising the cells for the comments.
Otherwise if you want to use the UIScrollView in case you have a lot of comments you will have to create manually a way to reuse them which is what the UITableView does.
If you want something like facebook, so that the context + comments both are movable,then go with option 2.
But, if you want content always at the top, go with option 1.
Indeed, UITableView is a subclass of UIScrollView.
And If you think you might have many comments like (50+),
If you use scrollView, then you should have to supply scrollView with those number of UIView objects.
But, if you use tableView, it perfectly reused already created views.So evenhough you have 1000+ comments, it just uses 5 UIView objects
I am gonna design a component in IOS, in which we will have Table view and Grid View; means user can see his data in table or grid. So what i am doing is i added a UIViewController and added two child view controller one for table and another one for collection view. I am handling everything using UIViewController only. Its means when user wants to use my component he has to add as a child view controller only. My question is that "Is it the best practice to use UIViewController like i am doing or Should I convert everything to UIView because UIView is light weight." I am gonna write only presentation logic in my component. We will get data from outside using delegate. And if i should use UIView then when should i use UIViewController?
Thanks
Your current approach is correct.
UIViews should do one and only one thing: paint a view when asked to.
UIViewControllers are more complex. They are are responsible for setting up views with any data they need to do their job, compositing multiple views (or view controllers) together if needed, responding to events from view components or from the device in general, and communicating with the rest of the code/system.
Because your code wants to show two different kinds of information, it fits the UIViewController much better than the plain UIView style.
As you've pointed out, Apple themselves have many examples of UIView subclasses that have delegates and do complex things. However, if you're writing a new component and it is complex (as yours is), I seriously recommend going for the UIViewController approach.
A note on history: Apple used to be of the advice that UIViewControllers should only show/composit UIViews and not other UIViewControllers (even though, confusingly, they didn't always follow their own advice!). This would align with their making of some quite complex UIView subclasses. However, they changed this stance a while back, and added support to UIViewControllers for compositing other UIViewControllers' views inside them. If Apple's stance had always been as it is now, you might find that some of their UIView subclasses were implemented as UIViewControllers!
As an experiment, it would probably be quite educational to try and implement your component both ways. I predict that you'd find UIView approach more unwieldy, with you having manually re-plumb some of the 'wiring' that you'd get 'for free' with the UIViewController approach.
Avoid putting logic in UIView subclass.
As I think you can make grid view by using table view just simply add multiple views on each cells
at time of switching grid to list or list to grid simply check your type and reload tableview
Maybe this is a silly question, but I've bumped into it a number of times during iOS Development.
Sometimes I'll develop a view component that I want to use on multiple screens, so I'll decide to subclass UIView and make it something I can use in multiple places.
Then, I start adding functionality to it. Maybe it needs to respond to an NSNotification, or it is supposed to respond to user touches.
At a certain point, I start wondering if I should really be making a UIViewController subclass, and add it to my UI as a child ViewController.
Is there any consensus on where to draw the line between adding some behaviors to a UIView, and when to create a full UIViewController?
I can't tell you about the consensus, but here's my opinion:
Subclass UIView only when...
You want to do custom drawing
You need to customize some behaviour of an already existing UIView subclass
You have special needs for layouting subviews. Most layouting can be done by UIViewController, though.
Maybe for special touch handling that you can't be done with gesture recognizers
Subclass UIViewController in all other cases. You almost always need a controller anyway, for writing glue code that ties together views and models, or for handling user interaction. Consequently, Apple has made it easy in UIKit to let controllers do all the work and to keep views as "stupid" as possible. For instance, it is very simple to nest controllers to create complex view hierarchies, without the need to have a single view subclass.
An indicator that subclassing UIView is not the first thing one should do is the section titled "Alternatives to Subclassing" in the UIView class reference. An indicator that subclassing UIViewController is the preferred thing to do is that there is no such section in the UIViewController class reference :-)
You should use a controller anytime that you need to handle or control data. Views are supposed to be as stupid as possible, not knowing what they are displaying but rather where. You can easily subclass and reuse ViewControllers. A good example, say you need to retrieve a string (or text) from the user throughout your app via a popover controller and a modal. Create a generic subclass of UIViewController that has a view with a textfield and a button. You can then use this view and it's controller in any capacity you need. Reusing it in the popover, modal or anywhere else (and generally passing the data back through delegation). Since you are dealing with data you should not being using a sole subclass of UIView.
From my experience I subclass UIViewControllers more often then UIViews. It is a little difficult for me to understand if you are solely talking about Containers or reuse of views in general application workflow. Either way though it should be the same.
I've used the embedded view controllers to load reusable table views from time to time. I've found that it's useful sometimes but not always. Communication between the two can be cumbersome, like if you want the embedded controller to communicate back up to the container. Delegation makes it easier but still cumbersome. It also limits you to iOS 6, if I remember right iOS 5 and lower don't support embedded controllers.
If it's just adding methods you can use a category to store some extra methods. I do that a lot on NSManagedObjects that I don't want to subclass and if I regenerate the NSManagedObject from the datamodel I don't lose the code in my categories. Gives me added functionality like calculated fields or conversion methods without having to subclass. If you don't need those methods for a particular instance just exclude the reference to the category.
Subclassing never is bad though IMO.
Often, when I'm making my apps, I'm in this situation : I have a UINavigationController, handling the view stack, some UIViewControllers, controlling their respective views...
But when I want to add several custom UIViews in my mainView, I don't know how to manage my code.
Each UIViewController needs to handle one and only one view (wich normally occupy all the screen size), and a view should not control their content (update it a the extrême limit).
You can't neither do this :
[myViewController1.view addSubview:childViewController.view];
So if I want to achieve something like this, what should I do ?
The orange parts have to be 3 instances of the same UIView(Controller?), but with a content depending of a NSObject (User, obviously).
I think this very important to segment your content, this should be an easy problem, but I found a lot of contradictory answers so, what's the best practice to handle this common issue?
Theses orange views should be instances of UIViewControllers in order for it to handle their UITableViewDatasource? Is addChildViewController relevant in this case?
I already found a lot of things which work, but I don't know what should I do...
Also, I'm using xibs.
Thanks in advance if you can help me (and other people I think).
You can do it either way (view or view controller) depending on how you want to handle things. Certainly, you can have one object be the data source for multiple tables, so in that case, you would just add multiple views. If, however, you want to keep your code more compartmentalized, then add view controllers, and have each control its own view -- to do this, you do need to use addChildViewController, and use the methods that Apple describes for creating custom container controllers. Alternatively, you can use container views in a storyboard which makes the process of creating custom container controllers simpler.
You're on the right path... Create separate instances of your subviews, and add them to your view. If you will have more than 3 (for instance, imagine coverview for your music, and you could scroll indefinitely left and right), I'd take a look at UICollectionViewController ... That will help manage cell re-use.
But, if it's just 3, just create three instances with different frames and add them to your view.
Here's how I'd do it:
each orange box will be a custom view (inherits from UIView)
the view will have the label, image and the tableview.
since you are not sure of the number of instances of these views you'd be using, its better to use some kind of tagging, so that you can have one place for the datasource and delegate methods of the tables in these orange views.
in the datasource and the delegate methods, you can make use of the tableView.tag (same as the orangeView.tag property).
I personally dislike having more than one viewController in a view (except the splitVC), probably because I haven't had a such requirement.
I dont see how a uiviewcontroller for orange box would help, over a uiview.
as #James Boutcher mentioned in his answer, UICollectionViews will simplify this issue further.
Why not creating a UIView class and overriding the drawRect method and then adding subView for this class in your myViewController1.view