Now,I gonna Develop an App ,which wants to switch from many different Views irregularly,also the views need to load large resources,AKA,it's hard to manage memory.Are there any good solustion?
PS：I created a ViewController as RootViewController,and When a button was Touch,run the code as
"ViewController=newController"
.The problem came,The new View loaded wrong way,it rotate so that couldn't show in a correct way.
I google for the solution,some one said ,I should replace the rootViewController,just like that,
[UIApplication sharedApplication].delegate.window.rootViewController=newController;
But I can't get/set the rootViewController in other class though it's a singleton.
Why not having a class that handles all the view switches ?
This article describes an architecture that might be helpfull: http://www.mikeziray.com/2010/01/27/handling-your-initial-view-controllers-for-iphone/comment-page-1/#comment-607
Related
I have a general working knowledge of object-oriented programming and I'm currently trying to create an interactive novel program in Objective C using Xcode 4.2 with storyboarding.
I have a storyController class that instantiates the page objects and a viewController class that needs to display the pages. My fundamental question is the best approach for my storyController to tell the viewController to update it's text to display that of the new page object. My instinct tells me that my storyController needs to call a method on the viewController and pass it a page object. However, I'm not sure how to reference the view controller since it seems to be automatically created and linked by the storyboard (I don't see the viewController instantiated in the appDelegate).
I've read this post: http://www.iphonedevsdk.com/forum/iphone-sdk-development/54859-sharing-data-between-view-controllers-other-objects.html and it seems to address the issue. I could make a shared object on my appDelegate and use KVN or NSNotification to tell the view controller to check it.
I've also been reading about delegates and protocols as possible solutions.
So considering these potentially different approaches, which would be best to tell my viewController to update itself and pass it an object that contains the updates?
I would suggest looking at the UIPageViewController class, which probably will do a lot of the heavy lifting work for you, depending on the specifics of your app. This class is essentially a controller class that contains multiple viewControllers. Each managed viewController becomes essentially a "page" in your book.
Here is a tutorial using UIPageViewController.
If this approach won't work for your app, I'd still suggest using a separate viewController instance for each "page" of your book and handle the transition between the pages with segues.
I created a new project "Single View Application" and designed the mainView with Storyboard. My main view contains a UIButton that opens the camera, the camera scans barcode and automatically goes to a website. Now I created a webView programmatically so that website can open and also created a UIButton inside the webView. Now I want that UIButton to act as home botton and return to mainview. I am unable to do that, please help.
ViewController.m code: http://cl.ly/FKj8
My storyboard looks like:
You really should look into the View Controller Programming Guide -- by switching around the contents of a single view controller, you're making a lot of extra work for yourself with little benefit. By using multiple view controllers when you want to have different "screens" in your app, you can take advantage of storyboarding for easier development, and you automatically get better memory management (read: less potential for crashes), too.
However, to more directly answer your question... if you're putting the WebView into the view hierarchy with [self.view addSubview:webView], you can remove it with [webView removeFromSuperview]. (This means you'll have to keep a reference to the WebView around so you can refer to it when you want to dismiss it.)
I also noticed in the code you posted to cl.ly an unrelated method -deviceModel which uses uname() to get device information. This is a bad idea, for two reasons:
uname() isn't guaranteed to do something useful on an iOS device (even if it currently does). Use the UIDevice class instead if you need this kind of info, or...
Generally, you don't want to test for the device name to enable functionality in your app; instead, you should test for the capabilities you need. (For example, if you look for a device name starting with "iPhone 4" to test for a Retina display, you'll miss the 4th-generation iPod touch, and the iPhone-5-or-whatever-they-call-what's-next. Instead, use the UIScreen class.)
Is it possible to communicate with a viewcontroller after a segue switched to another viewcontroller?
I want to know, because I need data from a viewcontroller passed on to the next viewcontroller,
but I just can't figure out how to get data from one viewcontroller to another, as they have no unique names or something which I can use to communicate with.
So can someone tell me:
If it is possible to communicate between viewcontrollers, and if possible, how?
Usually you do it the other way around, pushing values from the source to the destination. If you implement prepareForSegue in the view controller that is going to be segue'd out, you can use
[segue destinationViewController]
to get a reference to the destination view controller.
Then you can set any values in that controller that are needed using properties on that controller before it segues in.
I have searched for tutorials about making a MVC based iPhone app, but without success
Goto ITunesU and look for Paul Hegartys "iPad and iPhone Application DEvelopment" from stanford university
very good!
try the views presentingViewController property.
A typical OOP pattern is to create yet another object, a Model object (MVC paradigm), connect all the view controllers that need to communicate with this Model object, and pass any shared state or variables by setting and getting properties in this Model object. A common shortcut for very small apps is to use the App Delegate as a Model object, as any other controller can get a reference to the app delegate. But this shortcut is not very extensible to larger or reusable code.
I am making a application for the iphone and i am using window based application and i am doing this:
#importing all UIViewController class in the appDelegate class.
creating the object for accessing the variables and function and I am controlling all
action,event and controls from the appDelegate class.
I want to ask that is this right approach. I dont want to use view based application, I want to use UIViewController class just only controllers display.
If this is not a good approach for making the application tell me the good process for doing this.
I suggest you take a look at this:
http://www.icodeblog.com/2011/10/11/back-to-basics-an-introduction-to-view-controllers/
You should also read up on the iPhone-programming-basics, you will find a lot of nice tutorials and articles with a quick Google-search for "iPhone programming".
You could just create a singleton that holds the data and methods you want to share and access it from any view controller you want. Conceptually, it's not much different then what you are doing with the appDelegate class but it is better so that you don't clutter up the app delegate.
So I'm trying to use a UITableViewController (let's call it homeView) in my iPhone application to display a simple table with only a few rows of text which are loaded from an NSArray in the controller. I want to display the table in the grouped style in a subview of a subview (let's call it subSubView) of my main controller. When I try the following: [subSubView addSubview:homeView.view], my app crashes on launch. However, when I allocate the object without adding it to any views, it launches fine.
What's the best way (or rather a working way) to display the table generated by my UITableViewController?
There isn't enough to tell for sure what is going on, but if I had to guess I would think that you probably aren't retaining homeView. Normally I would say that as a comment to your question, since it is not really an answer, but I have a completely separate answer:
Just use a UITableView, not a UITableViewController. Instead of trying to embed a controller within a controller (which is quite difficult since Apple doesn't expose the necessary tools to actually modify the view controller hierarchy), just make the VC you are writing support the appropriate delegate/dataSource methods and directly create the view.
While it might make some logical sense to try to embed VCs inside of each other, with the exception of the builtin container VCs (UINavigationController, UITabBarController) it Really Doesn't Work™. The technical reason for this is that internally some of the event routing and messaging depends on parentViewController being correct, but since you can't set it (setParentViewController: is private) tons of latent bugs in UIKit start rearing their head. The internal collection classes can set the parentViewController correctly, so everything works right.
Also, one last thing. In your question you named your view controller homeView. Please, please on't do that. A view controller and a view are separate things, call it homeViewController. Aside from the fact that a lot of new iPhone developers get confused about what the distinction is, there is nothing more aggravating then tracing through someone else's code and realizing that something you are assuming is one type is another.