I'm using a storyboard. Let's say I have a view controller that's named MYviewController.
In - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender; I would like to substitute the view controller that I'm segueing to, by one of its child, for example: MYviewControllerChild1 OR MYviewControllerChild2. The child that's segued to depends on the sender parameter.
These view controllers have the same scene (in the storyboard). Only their behaviour is slightly different.
I have a tableView that shows the user the settings of the application. When he clicks a cell, it segues to a viewController where he can modify the value of some setting. Some of theses are alphanumeric, others are numeric. Depending on which cell is clicked, I'd like the input viewController to format the value accordingly (if it's a decimal value I'll use a NSNumberFormatter for example).
Is that possible?
As mentioned in comments to your OP, I believe you should handle this kind of scenario in one viewcontroller.
However, if you insist on using separate controllers, maybe because you think the functionality will be expanded later down the line and therefore add more diversity, you need to handle this by creating multiple storyboard scenes - one for each child controller.
The destination view controller in prepareForSegue is imposed by the viewcontroller at the end of the segue in the storyboard. I don't think there is any way to override that.
As described, your problem isn't really a good candidate for a storyboard. If you use a storyboard you will have to create and sync multiple scenes. Several possible solutions::
Create multiple storyboard scenes and invoke them manually via performSegueWithIdentifier.
Use a nib file instead of a storyboard for this scene. You can use a single nib file since the view controller is created outside the storyboard with [[VCClass alloc] initWithNibFile: bundle: You can create the appropriate view controller class and pass the same nib file to all instances.
Use a single storyboard scene and view controller and pass in typing information in your prepareForSegue.
Related
I need to navigate inside folders and files in directory (from server). The problem is that I don't know the number of folders so it's not possible to use performSegueWithIdentifier statically. How can I use navigation controller with dynamically number of view controllers in swift? I want to "push" a new view controller every time a user tap on a folder in order to list files/folders inside it and I want to do it with UINavigationController so the user have the possibility to go back with "previous" button.
Both storyboard and programmatically approaches are ok.
Thanks you
Storyboards and segues are just a crutch. Think about how you would do this without them. At each level, to go down a level, you would just instantiate a new view controller and push it onto the navigation controller stack with pushViewController:animated:.
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UINavigationController_Class/#//apple_ref/occ/instm/UINavigationController/pushViewController:animated:
And in fact it takes only one view controller class to do this, since any instance can create and push another instance of its own class. The display of one folder is exactly like the display of any other.
So if you wanted to configure this notion in a storyboard, you would have a circular segue, that is, the view controller would have a push / show segue leading to itself.
I agree with #matt's answer, just create the controller and push it. For sake of completeness, you can do this in a Storyboard with a segue.
Here's how:
So that you can call the segue programmatically, add an additional prototype cell to your tableView. (You do this because you don't want the segue to be automatically triggered when the tableViewCell is selected. By using an additional prototype cell, the segue can be wired up, but it will never be triggered automatically since this prototype cell will never actually be instantiated.)
Control-drag from this prototype cell to the viewController icon at the top of the tableViewController. Select "Show" from the pop-up.
Find this segue in the Document Outline View and give it an identifier such as "showFolderSegue" in the Attributes Inspector.
Now, when you want to trigger the segue, call: self.performSegueWithIdentifier("showFolderSegue", sender: self)
You can use prepareForSegue to set up the new tableViewController as you normally would.
This method too works with a single tableViewController.
I'm writing an app that uses storyboarding and I want to update the labels in one view by clicking a button in a previous view.
_label.text = variable1;
is the line I would use to change the value of label, which is in the next view, when I click the button. Using this method I can easily change labels in the same view as the button but it does nothing when I go to the next view and see empty labels.
I've tried looking everywhere and found similar issues but couldn't find anything that worked for me so any solution would be very appreciated!
Unfortunately, it is not possible to connect IBOutlets between different scenes in storyboard.
It is difficult to suggest some precise solution because you have to provide more details about the setup which you have. Still, it is possible to outline some possible solutions:
Using prepareForSegue
If the view controller which you want to modify appears after the segue is performed you can customise its appearance in prepareForSegue function.
Using delegation
You can assign the view controller which wants to modify another view controller as its delegate. For example, if ViewController1 wants to modify ViewController2:
#interface ViewController1: UIViewController {}
#property (nonatomic,weak) ViewController2 *controllerThatIWantToModify;
with such setup you can call:
self.controllerThatIWantToModify.label.text = variable1;
You use storyboards, so there must be a segue from your first viewController (with the button) to your second (with labels in it).
If it is the case, you can set up the labels of the second view controller from the prepareForSegue method of your first view controller.
This method is called with a segue object which has a destinationViewController property which is your second view controller.
If you have several segue from this viewController, you should check if it is the right segue and then set it up.
To do that you need to set up outlets that gives you access to the labels from the viewController.
Then you can either write a setUpLabelsWith:(NSString)text1 ... method in your view controller, or directly access the outlets from the first view controller (supposing their are not private).
Yes this supposes your second view controller has a custom class.
How should I go about creating a View for the storyboard programmatically? I want to access the labels from the first ViewController object made(automatically to call the IBAction methods of VC). I know that this first object of VC is the one linked to the view in the storyboard(?) and I need to change a label form another file, besides VC. I'm pretty sure the only way to do so would be to access the VC object that is linked to the view, or create one and not go with the default one that is created. If not, how would I go about accessing the labels of the view from another file?
You don't create storyboard objects programmatically. A storyboard is very basically an XML file Xcode uses to call different view controllers. The biggest advantage of using storyboards over NIBs is you can layout transitions or segues, and the advantage of NIBs or storyboards over initiating view controllers by code is obviously the visual interface. So your question doesn't really make sense.
If you want to reference a particular view controller's label from your storyboard you need to create a pointer to that view controller first, but changing it programmatically doesn't make sense because that's what storyboard is for.
That said you may just need to go look for your class name in your view controller's Identity Inspector in storyboard and then edit your label programmatically through an IBOutlet property.
I have a storyboard with a navigation controller that leads to an UIVIewController that I want to reuse. That UIVIewController has a ParentUIViewController that has all the basic functionalities for all the UIVIewControllers that I am reusing.
Currently I am copying and pasting (meh) and then I change the class of the UIViewController to the ChildUIVIewController that I want to use (ChildUIViewController extends ParentUIViewController).
But this sounds like a bad solution. Everytime I want to change the ParentViewController visually I need to update, manually, all other ChildViewControllers.
I have tried to create a xib for the ParentViewController but the xib isn't loaded because I need a xib with the name of the ChildViewController. I have created it and then said the class is the ParentViewController but it crashes in the segue.
EDIT
I have created an example of the status of my problem
https://github.com/tiagoalmeida/storyboardexample
Note that the ParentViewController has a set of logic way more complicated that is not illustrated there. Also note that I am also using a TableView. I hope that this can illustrate the problem.
Keep the logic on the parentViewController and the UI Part on the child UIViewControllers. If you need to create a new UIViewController, you will create a child that will have a corresponding XIB (or get rid of XIBs and create the interface by hand).
Have you considered looping back into the same UIViewController via a "phantom button"?
Have a look at this: UIStoryboard Power Drill, Batteries included
Essentially you can drag a Bar Button Item into the little black bar under the View Controller in Storyboard (the 1 with View Controller, First Responder, and Exit icons; sorry, I don't recall what this is called exactly), then you can control+drag from that button back into the UIViewController for a Push segue. This should create a loop segue in your Storyboard. All you need to do next is give that segue an identifier, programmatically call it from your code using [self performSegueWithIdentifier:], then implement -(void)prepareForSegue: and use [segue destinationViewController] to conditionally set the title and perhaps some flags so you can identify when to use different kinds of fetches (or other code variations) in the same Class code.
Can you associate child view controllers to a custom container view controller in Storyboard?
I can link child view controllers to a tab view controller, and I can link one view controller to a navigation controller.
What must I do to the container VC to accept child VCs?
As something of a combo of Caleb and Matt's answers, I did:
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"cpdc_check_embed"]) {
self.checkVC = segue.destinationViewController;
}
}
...where checkVC is a property on the container controller:
#property (weak,nonatomic) PXPCheckViewController * checkVC;
You just have to set your embed segue's Storyboard ID to whatever you want (in this case, cpdc_check_embed):
...and then check the identifier in -prepareForSegue:sender:.
Still not an outlet, but cleaner than Matt's (IMHO) and more specific than Caleb's, and you still get a nice-looking storyboard:
The storyboard deals with built-in container view controllers very nicely, displaying segues to child/root view controllers so that relationships are clearly shown. It is also nice how the children and parent view controllers are separated into different scenes.
If you want to achieve this effect in your own project, then there is a trick that is not perfect but very straightforward. In my example, suppose I have a container view controller that acts like a tab bar controller with only two tabs, 'left' and 'right'. I want to have a scene represent the parent view controller, and two separate scenes represent both the 'left' child view controller and the 'right' child view controller.
Even though it is impossible, it would be nice if I could create IBOutlets from the container view controller to its children in different scenes, and then when my container view controller is displayed set up the parent/child relationships according to the rules described the UIViewController documentation. If we had references to our 'left' and 'right' child view controllers, then we could set up the relationships no problem.
The standard solution to this referencing problem is to create references to child view controllers by dragging in Object outlets into the container view controller's scene, and then specifying their class type as being instances of the child view controller classes.
In order to keep children separated in different scenes like Apple's built-in containers, however, we will use a different trick. First, suppose we have the following properties declared in our container class, ContainerViewController:
#property (nonatomic, strong, readwrite) UIViewController *leftViewController;
#property (nonatomic, strong, readwrite) UIViewController *rightViewController;
In our storyboard, select the scene representing the 'left' view controller. In the attributes inspector, set the view controller's identifier property to "cvc_leftViewController" ("cvc_" refers to ContainerViewController, but really the identifier can be anything you want). Do the same for the right view controller's scene, setting it's identifier to "cvc_rightViewController".
Now insert the following code into ContainerViewController's viewDidLoad method:
if (self.storyboard) {
_leftViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"cvc_leftViewController"];
_rightViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"cvc_rightViewController"];
}
When ContainerViewController is loaded from the storyboard, it will go grab the 'left' and 'right' view controllers from their respective scenes and set references to them via its properties. Now that you have control of the child view controller instances, you can set up the parent/child relationships however you like. To learn how to do that properly refer to the UIViewController documentation.
This trick is not perfect, and has many caveats, but if you are careful you can make it work nicely for your project.
Edit: Although this is completely unnecessary and doesn't mean anything, if you really really want to have the storyboard display connections from your container to your child view controllers just like Apple's built-in containers, just use my method above and then set up segues directly between the container scene to the child scenes, and simply never perform those segues. Now everything will work correctly and look pretty too.
Can you associate child view controllers to a custom container view
controller in Storyboard?
I think what you're asking here is how to connect a view controller in one scene to an outlet of a view controller in a different scene. I don't believe that's possible, perhaps because the storyboard machinery may not have all the scenes in a storyboard loaded at the same time.
You're probably asking this because you want to pass some information from one view controller to another as you segue from one scene to the next. The way to do this when you're working with storyboards is to override -prepareForSegue:sender: in one or both view controllers affected by the segue. The UIStoryboardSegue object provided in the segue parameter has sourceViewController and destinationViewController properties, and also an identifier property. You can use these properties to identify the segue that's about to transfer data between the view controllers.
Ray Wenderlich's blog has a nice two-part tutorial on using storyboards that may help you:
Part 1 covers setting up a storyboard project, adding scenes, and creating segues.
Part 2 deals with using segues to transition between scenes, including the prepareForSeque method mentioned above.
iOS 5 allows multiple view controllers to be active in the same scene (although one should still be in charge), so a single scene in your storyboard might have several controllers. You can use outlets to connect these controllers to each other, and you can configure those connections the same way you did in IB: control-drag from one controller to another in the same scene. The usual outlet list will pop open to let you choose which outlet to connect.
The key to using multiple controllers in one scene (what I believe you are after here) is using the mysterious Object from the Objects list in IB to represent the other view controller and hooking up its outlets.
This answer How to create custom view controller container using storyboard in iOS 5 should help I hope. The answer also provides a working example app which is very helpful.
The problem with #Ben's (otherwise reasonable) answer is that it only works at one level of nesting. Beyond that, it would required that every subsequent VC is customized to save the nesting view controller in prepareForSegue.
To solve this, I spent too much time exploring an NSObject based index that that you could add to the Storyboard, bind to a scene, and which would then register it's parent VC in a global index, based on type and restorationId. That works / can work, but is too much effort in the end, and still requires the two step process of visually binding, and programmatically looking up.
For me, the simplest and most general solution is to lazily descend the view controller hierarchy
In my simple test project, I added the following lines to viewDidLoad:
self.left.data = [
"Zombie ipsum reversus ab viral inferno, nam rick grimes malum cerebro.",
"De carne lumbering animata corpora quaeritis." ]
where left is defined as:
lazy var left:CollectionViewController = { [unowned self] in
return self.childViewControllerWithId("Left") as! CollectionViewController }()
and childViewControllerWithId is defined as:
extension UIViewController {
func childViewControllerWithId(rid:String) -> UIViewController? {
// check immediate child controllers
for vc in self.childViewControllers as! [UIViewController] {
if vc.restorationIdentifier == rid { return vc }
}
// check nested controllers
for vc in self.childViewControllers as! [UIViewController] {
if let vc = vc.childViewControllerWithId(rid) {
return vc
}
}
assert(false, "check your assumptions")
return nil
}
}
Note that you could do other find variants based on type, if need be. Also note that the above requires that you define the restoration id in the Storyboard file. If you did not have repeated instances of the same view controller, then using type would be easier.
And to state what is hopefully obvious, you don't need to implement prepareForSegue, nor do you have to use the lazy loading, you just have to call find(...).