The app crashes in AppDelegate, unable to get beyond the launch screen. No view controller code ever gets executed.
The stack trace is also not very helpful nor is the line highlighted in AppDelegate when the crash occurs.
Images below provide the details.
How to debug from here?
Check any IBOutlet links carefully; you may have deleted the property from your view controller but the UI element is still connected to it. This should give you an exception stating something like Class ViewController is not key value coding-compliant for key XXX where XXX is your bad IBOutlet, however Swift's exception reporting does seem to be a bit hit-and-miss at times.
Here's another possible cause related to the reason Paulw11 stated that may help someone else.
If you have segue's in your storyboard that links to a storyboard reference in another bundle, and you change the name of the bundle where the reference resides, make sure to update the Bundle name in your storyboard for the linked reference.
I have a framework I'm developing that contains some storyboards and UI components. I decided to rename the framework, updated the podfile references in the app and all the file imports to reflect the new framework name but completely forgot that there were storyboard references in the app referencing view controllers provided in storyboards in the framework.
Here's an example:
If you do not rename the reference you will experience a crash when you try to load the storyboard containing your link with no hint as to why. I spent an embarrassing amount of time hunting this down.
I have recently started to learn iOS with obj-c from "iOS Programming The Big Nerd Ranch Guide 4th Edition". This edition was released in 2014 and is written with Xcode 5.
I am trying to make a simple app with two buttons and two labels. The labels are connected to two arrays and when a button is pressed an object from the corresponding array is shown in the corresponding text label (it's the Quiz app in chapter 1).
I created the project as a Single View app in Xcode 6, and put all my objects in the view controller class. I have two labels two buttons two arrays and an int to keep track of the object that has to be displayed from the array.
In the book it says that I should initialize the arrays in the initWithNibName method. I tried that but for some reason it never gets called. So I changed the initialization of the arrays to the init method. They initialize fine but when they are called from another method they are nil. Do you have any idea why this is happening?
The second issue I'm having is that I can't manage to get the contents of the storyboard on screen. It says that I'm supposed to make an instance of the ViewController inside the AppDelegate and make it the root window controller but all I get is a white window (or black in case I don't set the color).
UPDATE: I changed the intialization of the arrays from the init method to the viewDidLoad method and now they seem to be working fine. Nothing on the screen though.
It sounds like you're initializing your UIViewController from the app delegate AND a storyboard. If you create a new project in XCode, a "Single view application", you won't have to touch the app delegate at all in order to get something on the screen.
I believe both your problems are related to this, since it sounds like you're seeing an empty UIViewController on the screen (the one you create in the app delegate)
As for the initialization of your array, viewDidLoad is a popular place to do this.
If you are using storyboards, the method initWithNibNameOrNil will not be called. In the BNR book, it teaches you to use XIB files, which do use this method. If you are trying to follow the tutorials, I would suggest using XIB files.
For use of a book, I would suggest downloading whatever version of Xcode is being used for that book -- otherwise you will be running into a lot of confusing problems while learning.
If you would like to download previous version of Xcode, refer to this post:
How to download Xcode DMG or XIP file?
Is it possible to create a cocoa touch framework in swift which contain storyboard and viewControllers?
If yes can you give me a reference to a guide or something to get started? all the examples i see of creating frameworks are very simple classes which don't involve ui
I want to create a framework which involve UI
Yes, that is possible.
All you have to do is to create a cocoa framework as you normally do from File > New > iOS - Cocoa Framework..
Since this involves UI, Click on the project and right click > New > iOS - Storyboard. And after that it is just as simple as you do it in a normal app. Once your stuff is over in the framework side, you gotta create a new project to test your framework with UI (make sure that the class created in fw is a public class ).
To load the storyboard of your framework instead of your sample project's storyboard, do the full in ViewWillAppear method.
Create an object for storyboard along with the bundle (of your framework - normally it will be your VC's name)
instantiateInitialViewController
And present them
And you'll have your framework's storyboard in your sample project.
I currently have an Xcode project that uses storyboard and I have an Xcode project in which I followed a tutorial and made a simple weather view controller. This Weather view controller uses CocaPods and requires that I use .xcworkspace whereas in my previous Xcode project (the one in which I am making via storyboard) I have been using the .xcodeproj file. I am trying to bring the weather view controller project into my storyboard Xcode project. Hopefully, I will have a button on one particular view controller link to the Weather View Controller that was initially created in another application.
I have asked a previous question in regards to a project like this but with no luck. The previous question can be seen here: combining-two-xcode-projects-one-with-code-and-one-without
In order to test the one answer I as given on that previous question I went about and created a blank Xcode Project from scratch, uploaded all of the .h and .m files, and then went into terminal (I am using mac) and programmatically the pods. The pods installed perfectly. I then put down a button and used the IBAction mentioned in the question I posted the link to above:
//When the button is tapped
-(IBAction)buttonTapped:(id)sender
{
//initialize the code only controller
WXController *WXController = [[WXController alloc] init]
//present the view
[self presentViewController:WXController animated:YES completion:nil];
}
I then ran the project and came across this error that highlighted this piece of code:
WXController *WXController = [[WXController alloc] init]
The error stated:
"No Visible #Interface for 'WXController' declares the selector alloc"
Just to make sure nothing else worked, I also tried to open the same project with .wcworkspace and came across the same error which I wasn't able to figure out.
I figured it must have been a button with the linking of the view controller with the button so not only did I post prior to this but I also did my own research and didn't have any luck as well. I checked out these posts:
How to combine two projects into one project
Loading a storyboard from a different Xcode project
Just to make the question I'm asking more clear, I included a link to the Weather Xcode Application I am trying to link to my storyboard application. You should be able to open the application here: Link
I was wondering: What exactly am I doing wrong that is providing me with the "No Visible #Interface for 'WXController' declares the selector alloc" error and even if this is fixed, am I missing something or should the view controller display properly.
Also, I have previously been using the .xcodeproj for my storyboard Xcode application. Is it necessary that once I bring this Weather view controller in, I must switch to .wcworkspace? and if so, what is the difference/ positive/ negatives of each?
I'm using Xcode 4.2 and in the process of writing a universal app. I selected SingleView Application template when starting with a new project. XCode added ViewController1.h, ViewController1.m, ViewController1_iphone.xib and ViewController1_iPad.xib. I need to add more UIs and clicked on the File...New...New File and selected UIViewController subClass template and seeing two checkboxes (Targeted for iPad, With Xib for User Interface).
What should I do here to support both iPad and iPhone while at the same time have a common .h and .m files that share the same code. Do I need to add code to check whether it is a iPad or iPhone by doing this in my view controllers?
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
} else {
}
Also, I have seen people talking about ~iPad and ~iPhone. What is this all about?
If I understand correctly, do I have to design the UI separately both for iPad and iPhone due to different screen sizes?
I'm totally confused here.
Please help.
You can either add two nibs (one for ipad and one for iphone), or you can add one nib that will properly scale for either interface. Normally you'd add two nibs if you're making a view that will cover all or most of the screen, and you'd add one nib if you're making something small that will, perhaps, be fullscreen on iphone but displayed in a popover on ipad.
The tilde suffixes ~ipad and ~iphone are described under the heading “iOS Supports Device-Specific Resources” in the Resource Programming Guide. Notice that the suffixes are entirely lower-case, not camel-case as you wrote in your question. This matters because iOS uses a case-sensitive filesystem.
When you get a path for a resource using an NSBundle message like -[NSBundle pathForResource:ofType:] or -[NSBundle URLForResource:withExtension:], iOS will first look for the resource file with a suffix of ~ipad or ~iphone, depending on the current device. For example, suppose you do this:
NSString *path = [[NSBundle mainBundle] pathForResource:#"setup" ofType:#"plist"];
If you run this on an iPhone-type device (including an iPod touch), or on the simulator in iPhone mode, iOS will first look in your app bundle for a file named setup~iphone.plist. If it finds such a file, it will return the path of that file. If it doesn't find that file, it will instead return the path to setup.plist.
If you this on an iPad-type device, or on the simulator in iPad mode, iOS will first look in your app bundle for a file named setup~ipad.plist. If it finds such a file, it will return the path of that file. If it doesn't find that file, it will instead return the path to setup.plist.
All of the other APIs that get resources from bundles are built on top of NSBundle, so they all benefit from this device-specific lookup. That means if you use +[UIImage imageNamed:], it will automatically use a device-specific image, if you have one in your bundle. And if you use -[NSBundle loadNibNamed:owner:options:], it will automatically load a device-specific nib (.xib) file, if you have one in your bundle.
This simplifies your code, if you use the suffixes. If you create MyViewController~ipad.xib and MyViewController~iphone.xib, your app will automatically load the correct one for the current device. You don't have to check the user interface idiom; NSBundle checks it for you. (You could also use the names MyViewController~ipad.xib and MyViewController.xib and get the same effect.)
Now, you may have noticed that when you created your “universal” project, Xcode gave your project files named ViewController1_iPhone.xib and ViewController1_iPad.xib, which do not use the tilde suffixes, and it included code to look at the user interface idiom and choose a filename accordingly. Why does the universal project template do this? I don't know, but it is stupid. I suggest you fix the filenames to use the tilde suffixes and rip out the code that checks the user interface idiom.
I would recommend moving your .xib files to Storyboards, one for iPhone and one for iPad. They put a lot of joy back into development and are easy to learn.
Then, assign your custom class to your view controllers and link your UI elements to your code. If you do this for both storyboards, then they can both share the same code by referencing a common .h/.m file.
In the project settings, you then assign the appropriate storyboards to the iPhone/iPad deployment info once the app has been configured for universal development.
It's more or less up to you how you choose to implement things and structure things, but I tend to work with the following idea :
Ignore the 'Target for iPad' and 'With Xib' options (unless not using storyboards. See later)
Create a parent view controller that holds all shared code. E.G. MainViewController
Create 2 subclasses of this for both iPad and iPhone. E.G. MainViewController_iPhone and MainViewController_iPad (you could use MainViewController~iPhone which you mentioned. Simply a matter of naming preference here)
Any code that you want shared between iPhone and iPad, stick in the MainViewController parent class, and anything specific to each device place in the appropriate subclass
Generally you shouldn't really need to test if you're running on an iPhone or iPad. That's not to say that it's wrong and you shouldn't do it, but by separating the classes like this, you shouldn't really need to. But what I like to do is check what device I'm running on when I handle what orientations the device can handle, and put this in the shared parent view controller.
As for your UI, you've got 3 options.
- Use storyboards (I'd recommend this)
- Use separate XIB files
- Code everything manually
Depending on how much you now about iOS, coding everything manually can be more efficient, but will most likely take you longer. Using interface builder is nice and simple, although any customisations you want to make you'll still need to do in code but that's fine.
I'd suggest using storyboards so that you don't have loads of different XIB files. It also simplifies the split between iPhones and iPads, as you simply have 2 files for your interface. One will have all of your screens for the iPhone, and one will have all the screens for the iPad. iOS will automatically load the right storyboard at startup so you don't have to do anything. Then, to get your view controller and view, you can do something like :
MainViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:#"MainViewControllerIdentifier"];
Note that the identifier is specified inside the storyboard.
Hopefully this helps slightly, but if you have more questions just fire away :)
Here is what you want:
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
storyboard = [UIStoryboard storyboardWithName:#"ViewController1_iphone" bundle:nil];
}
else if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
{
storyboard = [UIStoryboard storyboardWithName:#"ViewController1_ipad" bundle:nil];
}
If you name your nib files MyNib.xib and MyNib~ipad.xib, the required nib will be automatically loaded, depending on the device your app is running on. However, it is not always necessary to create different nibs. If you don't require much customization, and it can be solved with the autoresizingMasks or you are setting some frames programmatically, it can be solved with only one nib. If you check the "targeted for ipad" part, your view in the nib will be larger, and the grouped tables look a little differently, but I don't know of any other difference in the outcome.
Hope this helps!