Using Xcode 4.3.3, I can't figure out how to connect outlets in a custom UIView class with objects created in Interface Builder.
In one ViewController, I have a variety of buttons, sliders, etc that I'm trying to group into Views. So, within that ViewController in IB, I added 3 views. Only 1 view will be visible at any given time.
I derived custom UIView classes to handle each of these 3 views. My view controller instantiates each of the classes. I selected the view(s) in IB, opened the Identity Inspector and set the Class(es) to my custom class(es). But when I tried dragging connections from the view and/or it's constituent controls to the custom view's .h file IB won't add a connection.
IB allows me to add outlets/actions by dragging to the parent view controller's .h, but not to the custom view's .h file. I thought once I set the View's class to be my custom class, I could drag outlets for the view's components to my custom class rather than in the view controller.
This question seems identical to mine: how to connect UIview outlets to a custom subview The two solutions (manually adding outlets and setting the view's class in IB) did not change the behavior for me. Here are the manual outlets I added:
customView3.h
#import <UIKit/UIKit.h>
#interface customView3 : UIView
#property (retain) IBOutlet customView3 *view3;
#property (retain) IBOutlet UISlider *slider;
#end
customView3.m
#import "customView3.h"
#implementation customView3
#synthesize view3, slider;
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
#end
What am I missing here? What else do I need to set/check in order to add outlets to my custom UIView rather than the view controller?
Note that I did get this to work today, but had to insert/type the outlets by hand in the derived class, then I could drag from the header file to the UI element in the Storyboard, but not the other way around.
I opened a bug with Apple. If anything interesting happens, I'll update this answer.
Updated 10/4/13: After much research, it seems the root of the problem is that IB believes that I'm trying to connect objects to properties within a class, that I'm going to then create a swarm of instances of this class and then IB won't be able to tell which instance should handle the messages. So, it disallows the connection on the belief that I'm (potentially) making simultaneous connections from one object to multiple copies of a property across several instances of the class.
My view is that I only want a single instance of the custom UIView, and that I should be able to tell IB, "don't panic, you're only dealing with this one instance."
I'm now focused on a new project and haven't had a chance to retry this in Xcode 5; however, given the info above, I'm not optimistic it will work in Xcode 5, either.
What you're trying to do is certainly both sensible (IMO) and possible. XCode is however quite quirky when it comes to establishing connections to outlets in subviews.
I've found that cleaning, rebuilding and sometimes restarting XCode tends to help, but sometimes it just doesn't work. In some cases I got it working by manually creating the outlet and dragging from the outlet to the control rather than the other way.
This is not very helpful, I know, but I just wanted to make it clear that this is supposed to work and when it doesn't it is most certainly due to a bug in XCode.
In my experience, you add IBAction and IBOutlet to subclasses of UIViewController and not subclasses of UIView. So within the MVC model, your "1" UIViewController has all of these IBOutlets in it and then you use the data from these IBOutlets to update your views.
So you are fine creating the UIViews objects in IB and then creating the corresponding classes in code and then changing the class of the UIViews objects in IB to your UIView subclass. Just put all IBOutlets in the UIViewController that has all the UIViews under it, get the values you need from the IBOutlets and then pass them down to (set them in) your UIView subclasses.
Hope this helps.
I had the same problem and found a workaround:
1) Open the Assistant Editor with customView3.xib on the left and customView3.h on the right
2) ctrl + drag from UISlider in customView3.xib to the customView3.h code on the right
3) An option to create a new Outlet connection will pop up.
4) Name the connection and click connect
It will then create a connected IBOutlet.
Related
Just starting out with an iPhone application using xcode 4.2.
I understand that it is good practice to use a subclass of UIViewController for each view in my application, and I am able to write some basic code in these to test buttons etc on the associated view.
Now I want to perform some action on a text field in one of these views, let's say I will use the Value Changed event to log the textfield's contents on each keystroke.
Should I be creating some kind of UITextField controller subclass? Or do I deal with this kind of thing in the existing ViewController subclass that houses the textfield?
If the latter, how do I refer to the textfield in the view controller subclass, and make the connections?
You'll probably want your UIViewController to implement UITextFieldDelegate. Connections can be made via the Interface Builder and outlets or just setting the delegate on the text field and using the reference you get from the delegate callbacks.
You would use the existing ViewController subclass that houses the textfield. A good rule of thumb is one ViewController per screen of views (not including UINavigationController, Modal screens, uisplitviewcontroller, and popovers).
To refer to it, you would make a property in the .h of your custom UIViewController:
#property (nonatomic,weak) IBOutlet UITextField * myTextField;
Note the IBOutlet keyword. This will allow you to connect it in InterfaceBuilder (or your storyboard). To learn how to connect that I would recommend you watch a video about IBOutlets since its more of a visual thing.
I was trying to use IB in a slightly different way that I am use to and I can't get it working extending the normal approach I use, when dealing with IB.
Instead of making a new UIViewController and have the view XIB generated for me and everything linked together by Xcode, I would like to just build a small (320x40px) View XIB and link it to my already existing ViewController.
I start out by making a new file in Xcode, select "view XIB".
I then open IB and add some labels etc. to the view and I set "Files Owner" to be my existing ViewController.
In my existing ViewController I set the IBOutlets for the labels etc. I put in my view.
I go back to IB and hook up the UILabels to my outlets in "Files Owner".
I would now think that I have a reference to the labels inside the XIB, in my viewController.
This is not really the approach I would like, I see no need for my viewController to have a reference to labels inside my view.
How I usually do in code:
My ViewController controls a bunch of UIViews made entirely in code and who instantiate them by:
UIView *customView = [[CustomView alloc] initWithFrame:aFrame];
[customView setTag:MY_CUSTOM_VIEW];
[customView setDelegate:self];
[self.view addSubView:customView];
[customView release];
After this I would access the labels, buttons etc. from my controller by using the [(UILabel*)[[self.view viewWithTag:MY_CUSTOM_VIEW] myLabel] setText#"Hello, World"];
have my UIViewController implement what ever methods the customView protocol required.
How to get that functionality with IB
Should I first build a MyCustomView class extending the UIView class, have it hold all my IBOutlets, set MyCustomClass as files owner and then instantiate that as shown above?
Is it OK to have a view act as viewController for the IB view and how would I relay actions to my "real" viewController?
What I would like to achieve is to deal with instantiating and laying out several UIViews in my UIViewControllers code, but have the freedom of designing some of these UIViews in IB.
All the info I can find is regarding the standard "build a UIViewController with a XIB for the view" or "How to build libraries of IB components".
I hope it makes sense and thanks for any help given:)
You can create whatever view structure you want in Interface Builder and then instantiate it using the UINib class. Once you create an UINib object it loads the contents from the nib and keeps them. Then, whenever you send it the instantiateWithOwner:options: message, it will instantiate the objects contained in the xib and return an array with the top level views. You can then add these views to your view hierarchy and handle them just like any other view you created programmatically.
If you keep the UINib object (as a property for example), you can instantiate the contents again and again, which allows your xib to be used like a template.
update: For a pre-iOS 4 workaround see my recent question and answer.
If I have a UIScrollView set up in the view via the Interface Builder, how do I get a reference to it in the ViewController implementation? I want to programmatically add labels to the scroll view.
For example, in C# if you have a textbox declared in the UI/form, you can access it by simply using the ID declared for that textbox. It doesn't seem this simple in objective c.
Thanks
Kevin
Assuming I understand you rightly and you are instantiating a view controller from a .xib containing subviews including the UIScrollView you want, there are two ways - first, you can find it in the subviews array that is owned by the view controller. Second, you can add an IBOutlet reference to it in your header file, then in interface builder make the connection using the connections inspector. Then you can refer to the object in your code, change frame, add labels etc.
You need to wire your ViewController up to your Nib files. This is pretty straightforward. This is your basic workflow for using Interface Builder on the iPhone/iPad:
Set the Class of the 'File's Owner' to the class of your view controller. You can do this by selecting the 'File's Owner' object in your nib window, pressing Command-4, and setting the class via the drop-down.
Create properties in your View Controller with the following format:
#property (nonatomic, retain) IBOutlet UIScrollView *scrollView;
The IBOutlet keyword is a macro that evaluates to nothing. So it doesn't actually do anything to your code, it just exists to let Interface Builder know that the 'scrollView' property can be bound to.
Control-drag from the object you'd like to bind to your ViewController. In the popup you can select the property you'd like to bind to the scroll view object.
This sort of stuff is pretty basic Xcode stuff. If you read any tutorial out there it'll cover this. Good luck, and enjoy!
edit:
I should add that if you used the default "New UIViewController Subclass" from the New File dialog, it will have done step one for you. You'll have a nib file and a View Controller that already know about each other.
Yes, the code you wrote is all you need in your header. Just make sure you connect the Scroll View object to the property in Interface Builder.
Yup! 'viewDidLoad' is added after all the connections specified in the Nib file have been made, so you can be confident that scrollView point to the correct object (assuming everything in the Nib is wired correctly, which is an easy mistake to make)
For quickly mocking up UI, I'd like to be able to drag buttons onto a view in interface builder, then drag a connection from that button to the view that should appear when you click it.
A subclass of UIButton is a little inconvenient to use in IB, so I'd prefer to add the behavior to UIButton itself. Unfortunately, it seems like outlets created in a category aren't visible in IB:
#interface UIButton (myextensions) {
IBOutlet UIView *outletDestination;
}
#end
Can extra outlets be added this way?
Can extra outlets be added this way?
Nope. You can't add instance variables by declaring them in a category.
You can, however, add properties, and you can put IBOutlet on properties, so you can add outlets that way. With the modern runtime (the only one available on the iPhone), properties can add instance variables.
I don't think you can do this if you intend to make a custom accessor for the property (you must use #synthesize), but it doesn't sound like this matters for your case: You're just mocking up UI, so you're not going to write custom accessors.
Alternatively, you can create outlets in IB itself on the Classes tab of the Library panel. Select a class there, then the Outlets tab in the pane below, then add an outlet to the list.
You'll need to have a nib open for that other solution, or no classes will show up. That's because it's context-sensitive: A Mac nib will have AppKit classes (like NSButton), whereas an iPhone nib will have UIKit classes.
I have a relatively simple app. I have a fullscreen UIView subclass (musicGridView) that the user interacts with, and a UIScrollView subclass (scrollView) that loads this class in, as well as a ViewController and mainWindow.xib.
Right now, I have a viewController instance loaded in the nib, which is of type myViewController. The nib also has instance of myUIView, which the myViewController is pointed to.
In AppDelegate, I do this:
[window addSubview:scrollView];
[scrollView addSubview: viewController.view];
scrollView.musicGridView = (MusicGridView*) viewController.view;
which I think is wrong. Ideally, the appDelegate doesn't have an instance of scrollView.
In scrollView's AwakeFromNib class, I do the initialization on the scrollView.
The way I think it should go, is load the [window addSubview:viewController.view] in appDelegate, and then point the viewController to an instance of scrollView instead of musicGridView. Then, in scrollView awakeFromNib add a subview of musicGridView.
Eventually, I want to create another view owned by scrollView that is actually a side TabBar (which isn't possible with the given API's) that the user can scroll to the left to reach.
So I guess amongst other MVC stuff, the question is, should the viewController point to the scrollView, which contains all other content UIView subclasses, including musicGridView?
It sounds like you are not using Interface Builder to design your UI. Since this is a new project, I would suggest doing that. You should not have to write any code like this at all. You will however need to describe your outlets and actions.
The two most important things you need to know when dealing with IB are the IBOutlet and IBAction keywords.
Sample class header:
#interface MyClass : NSObject {
IBOutlet UIScrollView* myScrollView;
}
- (IBAction) doWork;
#end
Now you can wire these two things up using Interface Builder by dragging sources to destinations with your mouse. YouTube has lots of tutorial videos on IB if you need a better description of how to do this.
I'm someone who doesn't use Interface Builder for UI design; in my experience, you need to go either all-IB, or all-programmatic. To solve your particular problem, I think you need your musicGridView to be an instance or extension of UIScrollView.
This can be done in your custom viewController's loadView method - simply initialize it to a UIScrollView (and add things to it), instead of a plain old UIView.
However, as described above, this approach isn't compatible with an IB-centric approach, as is confirmed in the UIViewController Class Reference
All subclasses of UIViewController
should implement the loadView method
to set the view property unless you
load your view from a nib file.