storyboard interview questions
Top storyboard frequently asked interview questions
How do I change the Navigation Bar color in iOS 7?
Basically I want to achieve something like the Twitter Nav Bar (updated Twitter for iOS7 that is). I embedded-in a nav bar atop a view controller. All I want is to change the nav bar color to light blue along with the utility bar at the top. I can't seem to find an option in my storyboard.
Source: (StackOverflow)
Which init method is called by the storyboard for UIViewControllers added to the storyboard?
Source: (StackOverflow)
i'm new to IOS developing and recently started in Xcode 4.5. I saw for every viewController that i could set some identity variables including the storyboard ID. What is this and how can i use it?
I started searching on stackoverflow and couldn't find any explanation for it.
I assumed it's not just some stupid label that i can set to remember my controller right? What does it do?
Source: (StackOverflow)
I am getting this warning from storyboard - prototype table cells must have reuse identifiers.
I have renamed the identifier in the attributes inspector but it does not seem to have removed the warning.
Any suggestions?
Source: (StackOverflow)
Xcode 4.5.2 gives me the following warning:
Unsupported Configuration
Scene is unreachable due to lack of entry points and does not have an identifier
for runtime access via -instantiateViewControllerWithIdentifier:.
Unfortunately I can't identify the incriminated scene. Selecting the warning in the Issue Navigator doesn't highlight anything in the Storyboard. I have a fairly complicated storyboard (30+ scenes).
Any suggestions?
Source: (StackOverflow)
Is it possible to design interfaces in landscape with Interface Builder? Others with the same question apparently were able to do so with an arrow at the top right of any selected view, but I see no such arrow. A picture would be helpful. (Note: I am using storyboards, not xibs.)
Source: (StackOverflow)
I have an iPhone application which has a storyboard. Now I want to provide an iPad application too. So I asked me whether there is a function which helps me convert my iPhone storyboard to an iPad storyboard.
To be specific:
Is there a similar function or is there only the manual way ?
Source: (StackOverflow)
Is it possible to cancel a segue in the prepareForSegue: method?
I want to perform some check before the segue, and if the condition is not true (in this case, if some UITextField is empty), display an error message instead of performing the segue.
Source: (StackOverflow)
Can someone explain to me what is the exact difference between modal and push segue?
I know that when we use push the segue gets added to a stack, so when we keep using push it keeps occupying memory?
Can someone please show me how these two are implemented?
Modal segues can be created by simply ctrl-click and dragging to destination but when I do that with the push my app crashes.
I am pushing from a button to a UINavigationController that has a UIViewController.
Source: (StackOverflow)
I keep getting the following error:
Storyboard (<UIStoryboard: 0x7ebdd20>) doesn't contain a view controller
with identifier 'drivingDetails'
This is the code:
- (void)tableView:(UITableView *)tableView
didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UIViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:@"drivingDetails"];
controller.title = [[dao libraryItemAtIndex:indexPath.row] valueForKey:@"name"];
[self.navigationController pushViewController:controller animated:YES];
}
I have already set the identifier on the UIStoryboard but I'm still getting this error.
Source: (StackOverflow)
In complex screens (View Controllers) I used to separate the whole thing in smaller pieces (I call them widgets). These widgets consist basically of a MyWidget.h and a MyWidget.m file as well as a MyWidget.xib file, where the root element is a UIView and the MyWidget class is the File Owner of the UIView. In the init of this widget I do a loadNibNamed.
In my View Controller I then do a [[MyWidget alloc] init], which I add to View's Controller main view as a sub view. This, so far, works perfectly.
I'm now wondering, how to do the same with storyboard, because I cannot really start to drag in a UIView somewhere, I always have to start with an UIViewController, which I don't want to.
If there is no possible way doing this with a Storyboard, can I simply do it the old way, by using the Storyboard for my main screens and segues, and use a separate .xib file to define custom views?
Source: (StackOverflow)
I have a storyboard set up with working login and main view controller, the latter is the view controller to which the user is navigated to when login is successful.
My objective is to show the main view controller immediately if the authentication (stored in keychain) is successful, and show the login view controller if the authentication failed.
Basically, I want to do this in my AppDelegate:
// url request & response work fine, assume success is a BOOL here
// that indicates whether login was successful or not
if (success) {
// 'push' main view controller
} else {
// 'push' login view controller
}
I know about the method performSegueWithIdentifier: but this method is an instance method of UIViewController, so not callable from within AppDelegate.
How do I do this using my existing storyboard ??
EDIT:
The Storyboard's initial view controller now is a navigation controller which isn't connected to anything. I used the setRootViewController: distinction because MainIdentifier is a UITabBarController. Then this is what my lines look like:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
BOOL isLoggedIn = ...; // got from server response
NSString *segueId = isLoggedIn ? @"MainIdentifier" : @"LoginIdentifier";
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Storyboard" bundle:nil];
UIViewController *initViewController = [storyboard instantiateViewControllerWithIdentifier:segueId];
if (isLoggedIn) {
[self.window setRootViewController:initViewController];
} else {
[(UINavigationController *)self.window.rootViewController pushViewController:initViewController animated:NO];
}
return YES;
}
Suggestions/improvements are welcome!
Source: (StackOverflow)
I'm using storyboards and I have a UITableView. I have a segue setup that pushes from my table to the detail VC. But which method should I use to handle this? I'll have to pass a couple objects to the detail view. But do I use didSelectRowAtIndex or -(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender?
Source: (StackOverflow)
Storyboards are rather a royal pain from a git workflow perspective when multiple people are collaborating on them. For example, the XML in the .storyboard file has its starting <document> tag's toolsVersion and systemVersion attributes altered by whatever configuration the most recent file manipulator happens to be running. Synchronizing everybody's Xcode versions precisely seems to help with toolsVersion, but systemVersion changes no matter what, depending on the specific Mac and/or OS X version the developer is running.
This is idiotic, but mostly harmless. What worries us, though, is that at other times some other changes are automatically made to the storyboard just by opening them after a git pull. That is to say, Alice makes changes to a storyboard, commits and pushes them to the repository. Bob then pulls Alice's changes and opens up the storyboard to make further changes. The moment he opens the storyboard, the file icon immediately changes to a modified-but-unsaved state, and a git status shows that any number of weird changes have occurred. All this without Bob having changed anything or saved the file himself.
The most common automated change we're seeing is the disappearance or reappearance of the entire <classes> tag hierachy near the end of a storyboard file. We haven't figured out what is causing this. We may have several localized versions of a storyboard in various .lproj directories, and when opening them inside Interface Builder, the class hierarchy may spontaneously be removed from some and added into others, or left alone in some. This causes a lot of noise in git diff, but it doesn't actually break any functionality. We will often selectively add the actual changes we made into git's index, commit those, and then just discard the spontaneous, nonsensical <classes> changes. This is to keep commits small and nice, as they should be. Eventually, though, it just becomes too much to bother with since Xcode keeps re-doing the changes, and someone just ragecommits them along with some other stuff... which is fine until someone else's Xcode decides to want to change them back for no apparent reason. (Our commit history has a lot of swearing over this.)
Is anyone else seeing this behaviour? Is this an Xcode bug or a configuration issue on one or more of our developer Macs? We've seen some similar behaviour when collaborating with XIB files, but storyboards seem more susceptible to this.
Source: (StackOverflow)
I have a UIViewController view as a subview/modal on top of another UIViewController view, such as that the subview/modal should be transparent and whatever components is added to the subview should be visible. The problem is that I have is the subview shows black background instead to have clearColor. I'm trying to make UIView as a clearColor not black background. Does anybody know what is wrong with it? Any suggestion appreciated.
FirstViewController.m
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
UIViewController *vc = [storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
[vc setModalPresentationStyle:UIModalPresentationFullScreen];
[self presentModalViewController:vc animated:NO];
SecondViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
self.view.opaque = YES;
self.view.backgroundColor = [UIColor clearColor];
}
RESOLVED: I fixed the issues. It is working so well for both of iPhone and iPad. Modal View Controller with no black background just clearColor/transparent. The only thing that I need to change is I replaced UIModalPresentationFullScreen to UIModalPresentationCurrentContext. How simple is that!
FirstViewController.m
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
UIViewController *vc = [storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
vc.view.backgroundColor = [UIColor clearColor];
self.modalPresentationStyle = UIModalPresentationCurrentContext;
[self presentViewController:vc animated:NO completion:nil];
NOTICE: If you are using a modalPresentationStyle property of navigationController:
FirstViewController.m
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
UIViewController *vc = [storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
vc.view.backgroundColor = [UIColor clearColor];
self.navigationController.modalPresentationStyle = UIModalPresentationCurrentContext;
[self presentViewController:vc animated:NO completion:nil];
NOTICE: The bad news is that the above solution doesn't work on iOS 7. The good news is that I fixed the issue for iOS7! I asked somebody for help and here is what he said:
When presenting a view controller modally, iOS removes the view controllers underneath it from the view hierarchy for the duration it is presented. While the view of your modally presented view controller is transparent, there is nothing underneath it except the app window, which is black. iOS 7 introduced a new modal presentation style, UIModalPresentationCustom, that causes iOS not to remove the views underneath the presented view controller. However, in order to use this modal presentation style, you must provide your own transition delegate to handle the presentation and dismiss animations. This is outlined in the 'Custom Transitions Using View Controllers' talk from WWDC 2013 https://developer.apple.com/wwdc/videos/?id=218 which also covers how to implement your own transition delegate.
You may see my solution for the above issue in iOS7: https://github.com/hightech/iOS-7-Custom-ModalViewController-Transitions
Source: (StackOverflow)