I have a design question. I have a scroll view that I want to use as a means of navigation. I.e. the user can slide between screens. At present, I am creating view controllers and putting their views directly on the scroll view:
aViewController.view.frame=CGRectMake(0,0,320,200);
[self.myScrollView addSubview:[aViewController view]]
Etc, for all 3 view controllers.
I know this isn't best practice. But I can't think of any other way of doing it. Ideally I would like to get the same behaviour as a navigation controller except the fact that I'll be using a scroll view. Any help would be greatly appreciated.
You have to be aware that this breaks certain UIViewController behaviors because these child view controllers do not get informed about interface rotation events and their viewWill/Did(Dis)Appear: methods will not work.
The alternative (until iOS 4.x at least) is to not use UIViewController subclasses for these subviews. You could easily create your own custom controller class (derived from NSObject) to manage a child view.
It's debatable whether that approach makes it easier overall, though.
I'm guessing what you're trying to achieve is something similar to this app?
http://itunes.apple.com/us/app/fanhattan-for-ipad/id436928538?mt=8
This app works in the same manner, using a scroll view for navigation. You can analyze that app, you'd get some ideas from it, i'm sure.
Related
There are some great answers relating to when to use a UIViewContoller vs. a UIView. For example here and here.
The general gist is that a UIVIewController should be used to control a full screen of data, because
It is designed to handle rotation. Only one UIViewController should be on the screen at once because only the newest will be notified that the rotation occurred.
To stay true to the MVC paradigm, your business logic should live in a UIViewController, while only display and interaction logic should live in a UIView. Presumably business logic relates to what's on the entire screen.
My question is, given this, how do I structure an app with left-right paging between several top-level views?
I want to create an interface with several UITableViews holding a list of recipes. The user swipes left and right to navigate between lists. There is a common menu on the bottom that stays fixed no matter what.
My initial thought is to use one UIVIewController for the UIScrollView, then add subviews from there.
However I'd really like each list to have its own UIViewController, so it can handle its own rotation, and hold business logic like its own REST methods. It would seem to be a pain to have the top-level UIViewController handle the rotation of a child subview, and it would seem to be a violation of MVC to put the logic anywhere else.
Is there a way to structure an app so that multiple UIViewControllers live inside a UIScrollView, or would it appropriate to use a series of top-level UIViewControllers and UISwipeGestureRecognizer to simulate the paging effect of the UIScrollView?
Thanks.
A couple of thoughts:
If targeting iOS 5 and higher, I'd suggest using a UIPageViewController which is designed for precisely this UI (swiping back and forth between UIViewController instances). You would then have a separate UIViewController for each recipe. In iOS 5, you only have UIPageViewControllerTransitionStylePageCurl transition style, but in iOS 6, you also have UIPageViewControllerTransitionStyleScroll.
For more information, see the Page View Controller section of the View Controller Catalog for iOS.
This is much simpler than writing your own scroll view based solution. If you "roll your own" with a UIScrollView, you'll want to remove instances that have scrolled off screen (by registering as the scroll view's delegate and responding to scrollViewDidScroll) so you don't use up memory unnecessarily.
If you do add child view controllers to your scroll view, don't forget to call the appropriate custom container calls. Specifically, as you add view controllers to your scroll view, make sure you call the following (assuming controller is the child controller and self is the main view controller):
[self addChildViewController:controller];
[self.scrollView addSubview:controller.view];
[controller didMoveToParentViewController:self];
And as you respond to scrollViewDidScroll to remove view controllers that are no longer visible, do the appropriate removal calls, e.g.:
[controller willMoveToParentViewController:nil];
[controller.view removeFromSuperview];
[self removeChildViewController:controller];
For information about why it's important to call these custom container calls, see WWDC 2011 video Implementing UIViewController Containment.
I definitely wouldn't recommend using a UINavigationController, though, because it will keep all of the previous pages in memory.
I believe for the requirements you're talking about you could use a UINavigationController. It will give you the "left-right" paging that you want and you can use a UIViewController for each of your recipes.
Also, I think you want to use a UIScrollView because it lets you perform a "swipe" gesture. If that's the case you could also add a UISwipeGestureRecognizer to your view controllers and every time the gesture is recognized call pushViewController:animated: and popViewControllerAnimated: to perform navigation between your recipes.
This is just and idea.
Hope this helps!
As far as I see, there are 2 good options:
Using a root UINavigationController and push/pop child
ViewControllers depending on the direction of the swipe gesture
(recognized by UISwipeGestureRecognizer, just as you said).
Using a root UIViewController with a UIScrollView and adding the child
viewcontroller views as subviews of the scrollview. To handle
orientation changes, you could pass the orientation-change
UIViewController methods (willRotateToInterfaceOrientation,
didRotateFromInterfaceOrientation) to the child controllers, so they
can handle them.
I hope I helped
Firstly, you should be aware that since iOS 5 it's been possible to include child view controllers inside your main view controller.
https://developer.apple.com/library/ios/featuredarticles/ViewControllerPGforiPhoneOS/CreatingCustomContainerViewControllers/CreatingCustomContainerViewControllers.html
So it seems to me that a good options would be to have a paged UIScrollView as your main controller, and then to put instances of your child controller onto each page.
Since that could all be a little memory intensive, you should really only have three instances at any one time (one being displayed, and one one either side so that they're ready if the user starts to scroll). The Apple demo project shows you how to configure a scroll view like that:
https://developer.apple.com/library/ios/samplecode/PageControl/Introduction/Intro.html#//apple_ref/doc/uid/DTS40007795
Hope that helps.
Is it a good practise to creates views in xcode and hide them and when required show them?
I am asking that because I prefer to create views visually and not in code.
If the view is to complex(a lot of subviews) should I create a new view controller to it?
I know there isn't a specify question here but I really need a clarification on this matter.
Regards
One of my first iOS applications had a tab bar and views that the user could switch between. Originally it was done by hiding and showing the right views depending on what the user pressed on the tab bar. This ended up being a complex disaster.
I then rewrote the app so that each tab bar view had its own UIViewController with its own set of views. That turned out to be so much easier to manage. (I also changed from using Interface Builder to straight code for creating the views, but that's beside the point and you can continue to use IB if you want.)
As for me, I prefer folowing practice:
Usually, a use storyboards,where views are placed, but if a view is complex, I create a separate XIB file, arrange all subviews there, and then in storyboard drag an UIView subclass and connect my XIB view with it.It helps to avoid mess in storyboard.
As for hiding views, I also don't recommend such practice as it can become very complex to understand your code and all those views are allocated when XIB is loaded, so the mobile developing rule "do as lazy as u can" is not met. We should try to spend as less memory as it's possible.
UIView is the best way to create iOS app, esp. if you want to reuse the code.
For example if you have same view to present in iPad n iPhone then using UIView can result in lots of similar code in View-controller
In another case if your view might need to have multiple table view it can be quite complex to handle each with delegates in ViewController. But separate view will solve this problem.
I have made my 1st open source code after learning how to use View
https://github.com/bishalg/BGRadioList
which I had learned from
http://www.raywenderlich.com/1768/uiview-tutorial-for-ios-how-to-make-a-custom-uiview-in-ios-5-a-5-star-rating-view
About the hiding view - I have used lots of hide and show view codes in my apps but believe me at one point it will become complex and unmanageable if you have lots of views.
I have a view that contains a mapview and a tableview, similar to how to the facebook nearby places screen looks in the facebook app looks.
I put the screen together using interface builder. I have outlets to the tableview and map. And, I set the UIViewController that controls the main view to be the delegate for both the mapview and table view. Everything works perfectly.
However, this main UIViewController is now pretty messy because it has to respond to methods on behalf of it's own view, the mkmapview and the uitableview. However, data is somewhat shared between the map and the table view.
I am wondering if this is where UIViewController containment comes in? Or, if I should should just make custom objects to act as delegates for those two views. I am looking for the correct design pattern to use in modern iOS. A few years ago just mashing it all into the same controller would be the way to go. Maybe it still is the way to go.
Both your ideas are good thoughts, but...
Controller containment is typically used for more navigation related purposes, like a UINavigationController.
Custom objects that do some of the delegate/datasource work, that's a good thought too, but a little clumsy to the extent that they share data with the view controller and each other. This might be a good solution especially if other view controllers will need the same delegate/datasource behavior.
A third alternative, and probably the best of the three, is to create class extensions of the view controller (see apple doc here). These can be thought of as parts of your class in different files.
I am exploring the design options for an iPAD application with multiple views on the different part of the main screen. I am going to have different ViewController for each of the view. UI is quite different from what any of the available view controllers (UISplitViewController, UINavigationController etc.) provide. I have been reading about the container extension api of UIViewController (especially addChildViewController):
http://developer.apple.com/library/ios/#DOCUMENTATION/UIKit/Reference/UIViewController_Class/Reference/Reference.html
(Look for "Implementing a Container View Controller")
However, it seems to me that this functionality is mainly designed for applications with UI that transition from one view to another (transitionFromViewController...). In my case, all of the views are visible at the same time. However, they do interact with each other. So my questions:
Am I missing something w.r.t. container extension of View Controller? I will still probably end up using this just to keep the list of child view controllers but don't see much value.
Can you recommend any other api/pattern that I should be using?
Thank you.
You can easy access to childViewController.
self.childViewControllers will return an array with all childs.
I asked similar question couple days ago: Maybe this will help you:
Get container VC instead of view
Take a look at http://developer.apple.com/library/ios/#featuredarticles/ViewControllerPGforiPhoneOS/CreatingCustomContainerViewControllers/CreatingCustomContainerViewControllers.html.
Add your various view controllers to self.childViewControllers and add the views of the child controllers as subviews of self.view.
Till now, I've been using controller or controllers like UITabbarController, or UINavigation controller to manage the UiviewController hierarchy. however, in the current project, i've been presented with a situation where my friends are recommending that I do away with controller of controllers and instead instantiate sub-UIViewControllers within the RootViewController and keep them as attributes. My question is whether this is a good practice MVC wise and memory management wise? (this is for iOS 5.0 with ARC)
The project requires a screen to have a header, main content area, and footer. the header and footer present dynamic content, but are the same for all screens but in the main content area, different screens can be presented either transitioning in from the right (like navigation controller would do it) or would appear modally.
I've tried to stick to MVC with one ViewController managing one view hierarchy... the above seems to go against it, but it seems to help in the situation.. so is this the right way to go or am I missing some other more optimal way?? Pls help
Thanks for your help in advance..
Why even have to have references to the view controllers themselves if you can just keep a reference to the view they manage? Sure it breaks MVC, but I love being able to divide reusable interface classes and then simply add their view's as subviews. It works, so long as you are smart about the whole thing. Is there anything specific about this pattern you'd like help with?
Go through this blog..Hope it helps you,
http://borkwarellc.wordpress.com/2010/07/22/qff-kitchen-mvc-part-1/