"viewWillAppear" not call in xcode 4.5 with iphone 4.3 simulator, but if it runs in iPhone 5.0 or iPhone 6.0 simulator, this method will be called.
why? and what can i do if i want to do something when the view of an controller will appear in ios 4.3?
I think it may be related to the "View Controller Abusing". Check if your container view controller is used correctly. You can refer to this post for detail.
Based on your comments, the problem appears to be the lack of container view controllers in iOS 4. As of 5+ you're explicitly meant to be able to add the view of any controller into the view of any other* and that will generate the appropriate view[Will/Did]Appear, along with all the other newer messages — viewDidLayoutSubviews, etc.
In 4 you weren't explicitly allowed to build container view controllers and there's no deliberate, specific backwards link that connects a view back to its controller.
As a result, when you add the navigation controller to your view it doesn't get viewDidAppear. Because it doesn't know that its view has appeared, it doesn't tell any of the controllers it contains that their views have appeared.
Probably the best you're going to be able to do is to hack around that by (i) checking if you're operating under iOS 4; and (ii) if so, posting artificial viewWillAppear/viewDidAppear/viewWillDisappear/viewDidDisappear to your contained controllers.
Based on personal experience, iOS 4 (at least in 4.3) does actually implement addChildViewController: but not to do what the later, documented version does. So despite it not being an entirely accurate functionality check I tend to use if([self respondsToSelector:#selector(presentingViewController)]) to determine whether I need to propagate these messages manually.
[*] and you should also call addChildViewController: to make sure all messages move correctly in all directions
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In my app, I've noticed that as I push and pop a view controller containing an MKMapView, memory usage steadily increases. I've determined that there is a problem with MapKit itself, not my code, though. I made a test project containing simply a navigation controller in which I repeatedly can push and pop a view controller containing nothing but a map view - no annotations or overlays.
My results indicate that this is a bug in iOS 6; in the iOS 6 simulator I see the gradual increase in memory usage. I suppose this is an issue with Apple's new in-house maps.
Any thoughts as to why this is happening?
If you push and pop the MKMapView in code over and over, you might want to make sure that you are letting control back to iOS so that it can actually release the view (Not putting the push and pop in a while(1) loop that is).
Maybe you should try turning off ARC and make explicit retain and release calls to the map view and see if you get better results, just as an experiment?
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.)
I'm working along with the book Beginning iPhone 3 Development, and am running into some issues on the "Pickers" app. I'm using Xcode 4.2, and I set it up exactly like they have it set up in their source code. All the code is the same, and all the outlet connections are the same. But, when I run my version, it launches a black screen, and the debugger says "Applications are expected to have a root view controller at the end of application launch."
There version in the source code runs just fine, and mine looks identical to it, but for some reason mine just won't run. I've Googled this issue and people have a bunch of workarounds, but I feel like there is something really simple in IB that I'm not seeing.
Any help would be great, thanks.
The iPhone 3 book is probably having you add the view of your view controller as a subview of the window, correct? Well, since iOS 4, UIWindow now has a rootViewController property and setting this property to your initial view controller is now the preferred way to get your first view controller on screen.
Basically replace something like this in -application:didFinishLaunchingWithOptions: in your application delegate...
[self.window addSubview:viewController.view];
with this...
self.window.rootViewController = viewController;
Quite a bit has changed since iPhone OS 3; beware as you proceed through the book.
Do you have the RootViewControllers XIB-file? And is it connected to the RootViewController Class (in designer)
I have some code that works fine on my iPod Touch running some 4.0-series iOS as well as the simulator that comes with the iOS SDK 4.1. But when I call [UIViewController dismissModalViewController:] on an iPhone 2 running iOS 3.1.2 it get an infinite recursion, eventually crashing.
I have a view controller that opens a table view where the user selects a document to open. Upon selecting a document my table view controller's delegate calls the parent view controllers dismissModalViewController method. I think it is because I'm closing the view controller whose code is running that causes this.
dismissModalViewController is documented to be available in iOS 2.0 and later.
How can I close the UIViewController that's open from its own code?
I figured my problem might be heap corruption from some previous code. A way to debug that is to comment off snippets of previous code to see whether the bug would go away or come back. Almost immediately I found that I was calling dismissModalViewControllerAnimated: on the current view controller's parent controller. Why that works in iOS 4.x I have no idea. The problem I face is that I have two modal dialogs that I need to close simultaneously, which I cannot get working, but that is a different question.
I couldn't find a good answer anywhere to this. I am using a UINavigationController for my iPhone app, with everything is generated programmatically, nothing in Interface Builder. I am trying to port my app to iPad, using a UISplitViewController and my existing UINavigationController, but I am not sure where I should have the logic of my program separating the view controllers for iPhone or iPad.
Do I set up my main file to use a different app delegate or do I use the same app delegate and have the user interface conditionally set up within it?
Besides this, whenever I try to compile my app on the simulator it does not recognize the UISplitViewController or even the condition in which I check if the class exists.
Can please someone put me in the right direction, remembering that I am not using any xibs?
If you want to see an example of a completely programmatic iPhone / iPad interface that uses a split view, you can download the source code of my application Molecules.
Within that application, I use one application delegate, but I set up the interface differently depending on which user interface idiom is present (iPad or iPhone). For the iPhone, I instantiate a root view controller which manages the appropriate interface for that device. For the iPad, I first create a UISplitViewController and attach it to the root window, then create my iPad-specific root view controller and place it as the detail view of the split view controller (with a navigation controller that I use for item selection as the left-hand controller for the split view).
Again, I recommend looking at that application project to see how I set this up programmatically. The code's available under a BSD license, so you can copy and paste this into your own application if you'd like.
As far as the compilation errors you're getting, you will need to migrate your application target to be a universal application using the "Upgrade Current Target for iPad" menu option. Once that has completed, set your build SDK to 3.2. Go to your application's build settings and set its Deployment Target to the earliest OS you want to support with your application (with 3.0 being the farthest back you can go).
Finally, you will need to weak-link UIKit. For how to do that, see my answer here. Weak linking of frameworks is no longer necessary if you are building using the iOS 4.2 or later SDK. Simply check for the presence of the appropriate classes at runtime by seeing if their +class method returns nil.