I am trying to have the ability to switch views in and out. The screens are generated on the fly and there may be anywhere from 30-100 of them that will be presented sequentially. A NavigationController may work, but I may be creating a hundred or so screens so I am worried it will run out of memory if I push that many views. Maybe this could work if I only ever added one screen at a time to the NavigationController, and when a new one is added remove all screens and then add the new one. But this may cause strange animations.
I tried creating a custom View Switcher that could load each of the views on the fly following the chapter 6 example in the apress book. The problem is that on rotations the events do not make it to the View Controller for the currently visible view. So it ends up doing weird things on screen rotations.
Another approach that I am thinking may work is to use a tab bar controller and make the tabs invisible. Then I can just use tabs 1 and 2 to hold the current view, and the last view and ping pong back and forth. Then memory is not as much of an issue as using a NavigationController.
Does anyone have any other ideas? I feel like there should be an easier way to do this that I am just not seeing.
How about creating a singleton "ScreenManager" that loads, adds and removes your views on your root view controller? This way you can make sure that the view hierarchy isn't convoluted and out of your control. It's also a good idea design-wise and should be very easy and efficient with memory management.
Related
I currently have my first app, which uses a storyboard. From the first view, I can be 8 model views deep before returning back to the start.
I think using XIBs (not storyboards) is better for my application. I would like to learn how to do all the views in code but all the books and tutorials treat code as a black plague. Hard to learn if no one teaches anymore.
My concern with my 8 deep modal string of views is that memory is consumed by each view and not released until I fall back to the start - releasing each one as I fall back.
My application is a state machine (so I want to simple move from one view to another), releasing all aspects of the view just being left. As I move from one state to the next, I release the current view as I move to the next one.
Can someone point me in the right direction?
Thanks.
You have a couple of choices. You could create a custom container controller (which would exist for the life of the run), and switch out which controller is embedded in it. As long as you have nothing pointing to the one that you replace, it will be deallocated.
A simpler solution, but one I don't really like to use, is to replace the window's root view controller with the next controller you want to go to, which will also cause the replaced one to be deallocated.
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 am a beginner at best when it comes to xcode, iOS, and objective-c. I have been working on a project that has had me looking up information a lot. I have already been learning a lot, but I realized lately that I have forming some bad practices.
I have used Storyboard to lay out the abstract view of the app. The first thing I noticed I was doing dealt with popover views for iPad. I did not know how to dismiss them via button press, so I was creating a new modal segue from the popover button back to the main view.
I realized that this was creating a new view and placing it over my existing view. This would start to chain until the program eventually crashed. Last night I learned the importance of delegates and how they can help me gracefully dismiss the popover view.
Based on the documentation I have read for modal views, it appears that I need to be dismissing those types of views as well.
My question regards to proper practice when building an app. What if I have a ViewController that has 10 buttons, each of which will spawn a popover that is similar yet features slightly different content. Is it OK to create 10 new views in storyboard and drag and drop the UI elements on there? This means that the main view controller is going to have 10 delegates, one for each.
OR would it be best to create one general view, load the content dynamically, and only worry about one delegate in the presenting view controller?
EDIT: As far as the differences between them, they each have a list of labels (questions) and a UISegmentedControl to match the label. This will allow the user to fill out a survey. There are currently 10 views because I have 10 sets of questions that I feel deserve different views. At the bottom of each view there are 4 buttons. Every view must include these 4 buttons.
It's "ok" but not practical to have those 10+ delegates. If these ViewControllers only differ slightly - have you considered creating a "base" view controller and then adding/updating some of the differences programmatically depending on the content? I think it all depends on what you want to display and how much these differ. I would definitely not recommend 10+ delegates all delegating back to the same controller.
Basically, I'm saying yes to your "OR" question.
Here is a screenshot of a view that I have right on my device.
The design issue that I am having here is that the top part of the screen is always going to be static - as far as its placement. The rest of the screen are a row of buttons added to this view programmatically. The arrows represent the idea that you could swipe in 4 directions(from top, from bottom, from left and from right) which would animate a new view onto the screen. This view is the same instance as the view before it. In fact all these views are the same instance but the buttons will be different.( i dont want to get too specific here.)
My design right now calls for pre-loading the views ahead of time. The data for each button for each view will be in core data. I will not know ahead of time how many views there are. One view might just have a view to the right that you can swipe in from the right and that view might have a top and bottom arrow - that would allow you to swipe from bottom or top that would be another view(same UIView subclass). So basically a tree of views.
I guess I am trying to figure out my options. A NavigationController is not really what i want because i have no need for a navigation bar, although in my mind it makes sense that i would have an array of view controllers here each with its view property pointing to each view that is allocated and then as i swipe i would bring in the appropriate view by using the view controller index.(through some animation code)
Another possible option would be UIScrollView but that seems cumbersome and may not be what i would really want.
One of the easiest setups would be to create a XIB file that would consist the top part of the screen and on the bottom an empty UIView that i would programmatically populate with the buttons(and their unique data). The problem that I am havign with this is, is how would i swap the views this way. I guess i could make the rootViewcontroller the first viewcontroller instance with the first view and then swap them.
I guess I am wanting to see if anyone had any questions or suggestions to come up with the easiest(most modular) approach to swiping in different views. Is using an array of view controllers the way to go?
A couple of thoughts:
This screams custom container view controller to me (if iOS 5 and above). See Creating Custom Container View Controllers in the View Controller Programming Guide for iOS.
You talked about using UISwipeGestureRecognizer. You could always contemplate UIPanGestureRecognizer, too. It's nice to have continuous gestures. Think about reading a book where the page swipe tracks your finger, but you can stop and go back, mid gesture. Sure, start with swipe gestures for now, but if your UX lends itself to it, you can always contemplate continuous gestures in the future.
You said that you're planning on "pre-loading the views ahead of time". Generally, given the limited memory capacity of mobile devices, you'd want to be more conservative than that. Maybe load the current view, and the four ones that you're likely to go to in each of the four directions (so that you can present them instantaneously), but leave it at that. Once you go to one of the four possible destinations, then go ahead and release the ones that are not reachable from the current one and tee up the ones that are.
One Xib is enough for you (for this part of your app anyway).
Don't use a UINavigation Controller. The NavController metaphor is one of a stack of cards. You don't have that data structure.
The general idea is one ViewController for one screenful of stuff. If you feel the need for two viewControllers (one for the top part, one for the bottom part) then you are going to have to look at custom container controllers, to ensure that the contained controllers receive their instance methods correctly (viewDidLoad, viewWillAppear, etc). An example container controller managing a pair of viewControllers is the iPad splitViewController. But I don't think you need to do this.
I suggest placing a scrollView on the lower half of the screen and using that to manage your data views. If the upper part of the screen also needs to change (under other conditions) you could even have two scrollViews, one up top, the other below. They can be paged, and contain views that are the exact size of the respective screen portion. They can share their single containing viewController as a common location for their delegate methods.
I can't really help you with more detail, as I don't have a precise enough idea what you want to achieve. Perhaps you should try and implement it one of these ways and come back here with more questions as your ideas become concrete. Start out with the simplest idea (eg scrollView inside a single viewController), only chuck it out when you find you have to break it!
update
following your comments, I do think a scrollView might work for you. I think that managing a stack of view controllers with a custom container controller (as Rob suggests) could get overcomplicated. You will have to create your own custom container controller, the pre-existing ones such as UINavigationController are not appropriate for your data strucure (from what I can gather anyway).
You won't need to manage tons of UIViews, in fact you only need 5 - one for the onscreen portion of the scrollView, one for the screen immediately left and right, and similarly for the immediate one above and below. You can reuse these views as you swipe, much the way that tableViews reuse their cells. The rest of it will be about manipulating your data so the right content is arranged in the views as they come onscreen.
See my answer to this question for some more ideas on this: UICollectionView horizontal continuous loop
I have a ViewController (with navigation) that needs to show 7 different content layouts. I want to keep the same background and nav, the only thing that needs to change is the central UIView.
If I have 7 different UIViews on the same xib/storyboard, can I hide the ones I'm not using or will that ding performance?
Using segues won't work either because they make a mess out of my custom navigation and animations.
Is there a better way to accomplish what I am trying to do? Thanks for suggestions
solution
My design is too custom for using view controller containment so I decided to mimic the idea with a custom UIViewController and two UIViews. It's not too bad and it works rather quickly.
You should look into using view controller containment, then you can load your views from separate nib files and still provide your custom navigation and animations from your container view controller.
Note: This is only really supported from iOS 5.
Generally, it's a good idea to unload views that aren't visible, however, if your views aren't using too much memory (and/or cpu time) hiding them when they're not in use should work fine.
View controller containment is probably what you should be doing if each view has its own unique functionality (i.e. view 1 is a map, view 2 shows some about text, view 3 is an image gallery). UITabBar might be useful, but it depends on your app.
The performance hit would depend on your views' contents. If you haven't done so already, invest some time into learning how to use Instruments (apple's diagnostic tool). Watching the video titled "Optimizing App Performance with Instruments" in the developer resources would be a good start.
My design is too custom for using view controller containment so I decided to mimic the idea with a custom UIViewController and two UIViews. It's not too bad and it works rather quickly.