Let's say I have a simple NSDocument subclass:
#interface Document : NSDocument
#property NSString *someText;
#end
I want to map someText to some field in my view - so I add a new field to my view controller:
#interface ViewController : NSViewController
#property Document* document;
#end
...and make sure to store my document:
- (void)setRepresentedObject:(id)representedObject {
[super setRepresentedObject:representedObject];
self.document = ((Document*)representedObject);
}
Oh yeah, and I make sure that the document property is dynamic, which a bit of googling brought up as important for data binding:
#implementation Document
#dynamic someText;
#end
Then head on over to my NSTextField and try to bind the value:
As you can see, it reports that "Xcode cannot resolve the entered keypath." Furthermore, the "Controller Key" field (which I believe is where I'm supposed to specify document, with self.someText for the keypath?) is entirely greyed out.
What am I doing wrong?
It turns out that #dynamic isn't necessary - what is necessary is that the view controller's representedObject is set quite early.
I modified the default generated makeWindowControllers in the Document class so that it sets representedObject on the just-created WindowController's contentViewController before addWindowController is invoked:
- (void)makeWindowControllers {
NSWindowController *wc = [[NSStoryboard storyboardWithName:#"Main" bundle:nil] instantiateControllerWithIdentifier:#"Document Window Controller"];
wc.contentViewController.representedObject = self;
[self addWindowController:wc];
}
And then, in my storyboard, I simply bound to View Controller with a Model Key Path of representedObject.someText. (Be sure to check off "Continuously Updates Value" if things still don't seem to be changing - otherwise the data model might only be updated on certain events such as focus change.)
Related
Simple structure:
exampleController.h :
#import <Foundation/Foundation.h>
#interface exampleController : NSWindowController {
#public
IBOutlet NSPanel *entryPanel;
#property (nonatomic, strong) IBOutlet NSPanel *entryPanel;
#end
exampleController.m :
#import "exampleController.h"
#implementation exampleController
#synthesize entryPanel;
- (id)init {
self = [super initWithWindowNibName:#"ExamplePanel"];
if (self) {
// Initialization code here.
NSLog(#"entryPanel: %#", entryPanel);
[self.entryPanel setTitle:#"TESTING!"];
}
return self;
}
randomController.m :
...
- (id) init {
self = [super init];
if (self) {
// loading our example controller if it isn't loaded yet.
if (!ourExampleController) {
ourExampleController = [exampleController alloc] init];
}
}
return self;
}
...and then later in the random controller within a method I show the NSPanel via:
[ourExampleController showWindow:self];
[ourExampleController window] makeKeyAndOrderFront:self];
My problem is that no matter what, the first time the NSPanel displays and shows itself the title is always still set to the title that it has in Interface Builder! Even though I explicitly set the title in the exampleController init method.
I've also tried throwing an NSLog(#"entryPanel: %#", entryPanel) in the init method for exampleController and at launch it is always NULL. I do not have to ALLOC all my IBOutlets in the init because I am already synthesizing them?
I've double checked everything in interface builder. The File Owner for the ExamplePanel.xib is set to the exampleController class. The window AND entryPanel outlets are both referencing the NSPanel in our xib file. What am I missing ??
Thanks in advance!
EDIT: Just to add. If I open the window (..and see the default IB title) and then close it and reopen it with a method that changes the title - it seems to work! This problem seems to only reside with the window first opening. It seems like my properties are not being alloc'd until the window first opens?
EUREKA!
As per discussion here:
IBOutlet instances are (null) after loading from NIB
I learnt that the window itself is not loaded when my controller is initialized. Found that surprising since I figured using initWithWindowNibName:#"myNibFile" would also alloc and initialize all outlet properties but since I'm new to OSX Obj-C that appears to not be the case. All the outlet properties are only alloc'd once the window itself is loaded too.
It's easy to just show the window (which also loads the window if it's not loaded yet) and then quickly set all the outlets to my desired values BUT this was an issue for me since I wanted to avoid that ever so slight "screen flicker" (for lack of a better description) that occurs as the values adjust to their new settings.
The solution was to find a way to load the controller and load the window without actually showing it first! Then I discovered this:
Can you force a NSWindow to load, i.e. before it is presented onscreen?
Steps to make that happen:
Add the following to my NSWindowController subclass init method:
// this loads the window as per link/description above
[self window]
The key seems to be though to ensure that in your NIB/XIB file that the Visible At Launch is unchecked. If it is checked (default behavior) then the [self window] call above will still show your window when your app launches. Unchecking the above option ensures the above call does not show your window until you explicitly show it yourself!
E.g. You can define an action button which loads your window:
[exampleController showWindow:self];
[[exampleController window] makeKeyAndOrderFront:self];
Hope this helps someone else out. Was a head scratcher for a couple hours!
You should set the title, etc. in -awakeFromNib or -windowDidLoad instead of an -init… method. That way the values will be set before the window is shown and you won't get the flicker.
I am creating some sample applications to understand the concepts of view navigation, binding etc in cocoa.
Here is the scenario:
I have a window that has a tab view(2 tabs) in MainMenu.Xib.
I have a text field in the first tab and label in the second tab. I want both of them to reflect the same value and I want to do this using binding. Also, I don't want to use the views provided to me along with the tab view.
These are the steps I have done.
The view of each tab view item is set separately in the applicationDidFinishLaunching: method using the following code:
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
// Insert code here to initialize your application
//initialize view controllers
view1=[[ViewTab1 alloc] initWithNibName:#"ViewTab1" bundle:nil];
view2=[[ViewTab2 alloc] initWithNibName:#"ViewTab2" bundle:nil];
//set views
[[[myTabView tabViewItems] objectAtIndex:0]setView:view1.view];
[[[myTabView tabViewItems] objectAtIndex:1]setView:view2.view];
}
myTabView is the outlet reference of the tab view from MainMenu.xib in AppDelegate.
ViewTab1 is the name of the first view controller (and the xib).
ViewTab2 is the name of the second view controller (and the xib).
ViewTab1 has one single text field (and an associated label). I have bound this to a variable(name) declared in AppDelegate.
ViewTab2 has a label. I have bound this also to the same variable in AppDelegate.
The variable, 'name' is initialized in the init method of AppDelegate.
AppDelegate.h
....
NSString *name;
....
#property(strong) ViewTab1 *view1;
#property(strong) ViewTab2 *view2;
#property (assign) IBOutlet NSTabView *myTabView;
#property (strong) NSString *name;
....
AppDelegate.m
....
#synthesize myTabView;
#synthesize view1,view2;
#synthesize name;
....
- (id)init {
self = [super init];
if (self) {
name=#"dummy";
}
return self;
....
Apart from this I haven't done any coding in my program.
In the ViewTab1.xib I got an object and made it an instance of AppDelegate and then connected the delegate reference of the Application object(NSApplication) to the same object. (I hope this is the right way of getting the AppDelegate object.)
I did the same in ViewTab2.xib
Then I bound the text field in ViewTab1 and label in ViewTab2 to this variable in AppDelegate.
When I run the program both the text field and label shows "dummy". But when I change the value in the text field, its not reflected in the label in the second tab( i.e. ViewTab2).
Please tell me what I'm doing wrong.
How to establish binding to the same App delegate object from any loaded Nib?
Yes, I know this frustrated situation as described in question... after many weeks and hundreds pages of documentation for KVO - Notifications - Bindings I think there is one very simple solution for that.
As we can find in some information sources the nib-loading process produce new instances of members... and we need to use binding connection to the old one.
Note that bindings made in InterfaceBuilder are redirect to these new instances automatically after loading nib
Why not redirect the pointer of App delegate to the old instance?
In method where you loads your nib you can test which object is app delegate before and just after nib load.
If the new one isn’t the same as the previous one you can redirect it as you want.
This simple example works for me in Xcode3 under 10.5.8 with target to OSX10.5 / i386:
// ***** SOMEWHERE IN DEFAULT APP-DELEGATE.m IMPLEMENTATION
- (IBAction) createOtherWindowFromNib: (id)sender
{
// ensure that app delegate is set as you want...
[NSApp setDelegate:self];
NSLog(#"APP-DELEGAT **** CREATE-TEST-WINDOW ***** WHO IS APP-DELEGATE BEFORE NIB LOAD: %# ", [[NSApp delegate] description]);
// we can bind members of the nib to this controller over proxy object named "File’s Owner"
NSWindowController *otherWinCapo = [[NSWindowController alloc] initWithWindowNibName: #"OtherTestWindow"];
NSLog(#"APP-DELEGAT **** CREATE-TEST-WINDOW ***** WHO IS APP-DELEGATE AFTER NIB LOAD: %# ", [[NSApp delegate] description]);
// make some test for delegates before/after here if you need ...
// usually your bindings made inside "OtherTestWindow.xib" by IB doesn’t works in this moment
// ... and some redirection if needed
[NSApp setDelegate:self];
// afer that the bind made in IB inside "OtherTestWindow.xib"
// referred to (proxy object) "Application.delegate.myBOOL" (Bind to:Application, Model Key Path:delegate.myBOOL)
// react to changes of myBOOL placed in default app delegate object as expected
// simultaneously in every open instance of "OtherTestWindow.xib"
[otherWinCapo showWindow: otherWinCapo.window]; // we need populate the window instance on screen to see it
}
I think the problem is that the objects in your xibs that you set to the app delegate class create 2 different instances of the app delegate, so changing the value of the text field changes the value of name in one instance but not in the other. That's what you're doing wrong, unfortunately, I can't think of a solution at this time.
Have you turned on 'Continuously Updates Value' in the NSTextField controls?
See this example.
I was wondering how I could access data from another class using Xcode 4.2 and Storyboard?
Say for instance how would I access the text of a text field from another class?
Google hasn't helped and the lesson on MyCodeTeacher.com about this is outdated and doesn't work anymore...
Thanks for bearing with me!
-Shredder2794
Not sure if this is the only or best way, but you can create a property in the destination view's .h file and set it to a value before the segue is performed
in the destination view controller's .h file:
#interface YourDestinationViewController : UIViewController
{
NSString* _stringToDisplay;
//...
}
#property (nonatomic, retain) NSString* stringToDisplay;
//...
and in the presenting view's .m file
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
YourDestinationViewController*viewController = segue.destinationViewController;
viewController.delegate = self;
viewController.stringToDisplay = #"this is the string";
}
Then you can do what you want with the property in whichever of the viewWillAppear/viewDidLoad/viewDidAppear/etc. methods best suits your purpose in the destination view's .m file
And then to check if it works, in the destination view controller's .m file:
-(void)viewWillAppear:(BOOL)animated
{
NSLog(#"self.stringToDisplay = %#", self.stringToDisplay);
...
//and if a label was defined as a property already you could set the
//label.text value here
}
Edit: Added more code, and made it less generic
This isn't specific to Storyboard. There are several ways to do what you are trying to do. You could declare a variable in your AppDelegate (an NSString) and set that in your first class. Then in your second class access the AppDelegate variable and use that to set your label. The code to do this is:
AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
label.text = appDelegate.myString;
Another way to do it (probably the easiest) is to declare an NSString in your second class. Then in your first class, before you push the second view set that string variable. Something like this:
MyViewController *vc = [[MyViewController alloc] initWithNibName:#"" bundle:nil];
vc.myString = #"";
The third way to do this is using delegates. This is the most 'complicated' way but is the best. You would create a delegate which gets called when your second view appears. The delegate could then return the value from the first class to you.
You may also be able to use the new completion handler block on the iOS 5 pushViewController: method.
Edit:
Custom init method:
- (void)initWithNibName:(NSString *)nibName bundle:(NSString *)bundle string:(NSString *)myString
And then when you are pushing the view just class this method and set the string through it.
Working on an experiment on the iPad. Tried some variations on how to do this, but I can't seem to get it to work correctly...
I tap a UIButton on my MainViewController and a TextEntryModule is added to the view. TextEntryModule is its own class (for multiple instantiation) and it contains a UITextView called TextEntry (this all works at the moment).
I tap on the TextEntry UITextView and it brings up the keyboard and another view (located in MainViewController) with a UITextView called TextPreview. (this also works at the moment).
The part I'm having trouble with is synching the two UITextViews. The idea being that when I type into TextEntry, the text in TextPreview will also be updated.
Outlets are linked properly for the text fields, but I think I'm missing something "obvious":
TextEntryModule *tm = (AnnotationModule *)currentModule;
TextPreview.text = tm.TextEntry.text
Thanks in advance!
UITextView: delegate.
- (void)textViewDidChange:(UITextView *)textView
Then assign it the value of the other textview in this method.
Edit
#interface MainViewController <UITextViewDelegate> {
...
}
...
#end
Then you implement this method in the implementation file of MainViewController
#implementation MainViewController
//More code
- (void)textViewDidChange:(UITextView *)textView {
TextEntryModule *tm = (AnnotationModule *)currentModule;
TextPreview.text = tm.TextEntry.text
}
#end
Then you will have to set the TextEntryModule object's delegate to self since the controller now conform to the protocol and can "act" upon this notification.
You need to become a UITextFieldDelegate and monitor when text changes in the one field and then update the other field. Take a look at the documentation on it.
I know this question has been asked several times and I did read existing posts on this topic but I still need help.
I have 2 UIViewControllers - parent and child. I display the child UIViewController using the presentModalViewController as below:
ChildController *child =
[[ChildController alloc] initWithNibName:#"ChildView" bundle:nil];
[self presentModalViewController:child animated:YES];
[child release];
The child view has a UIPickerView. When user selects an item from UIPickerView and clicks done, I have to dismiss the modal view and display the selected item on a UITextField in the parent view.
In child's button click delegate, I do the following:
ParentController *parent =
(ParentController *)[self.navigationController parentViewController];
[parent.myTextField setText:selectedText];
[self dismissModalViewControllerAnimated:YES];
Everything works without errors. But I don't know how to load the parent view so that it displays the updated UITextField.
I tried
[parent reloadInputViews];
doesn' work. Please help.
Delegation is the way to go. I know some people that may be looking for an easier solution but trust me I have tried others and nothing works better than delegation. So anyone having the same problem, go read up on delegation and follow it step by step.
In your subviewcontroller.h - declare a protocol and declare delegate mthods in it.
#protocol myDelegate
-(void)clickedButton:(subviewcontroller *)subController;
#end
In your subviewcontroller.h, within #interface:
id<myDelegate> delegate;
#property (nonatomic, assign) id<myDelegate> delegate;
NSString *data;
-(NSString *)getData;
In your subviewcontroller.m, synthesize myDelegate. Add the following code to where you want to notify your parentviewcontroller that the subview is done doing whatever it is supposed to do:
[delegate clickedButton:self];
and then handle getData to return whatever data you want to send to your parentviewcontroller
In your parentviewcontroller.h, import subviewcontroller.h and use it's delegate
#import "subviewcontroller.h"
#interface parentviewcontroller : VUIViewController <myDelegate>
{}
In your parentviewcontroller.m, implement the delegate method
- (void)clickedButton:(subviewcontroller *)subcontroller
{
NSString *myData = [subcontroller getData];
[self dimissModalViewControllerAnimated:YES];
[self reloadInputViews];
}
Don't forget memory management!
If a low-memory warning comes in during your modal view's display, the parent's view will be unloaded. Then parent.myTextField is no longer referring to the right text field until the view is reloaded. You can force a reload of the view just by calling parent.view;
However, a better idea might be to have the parent view have a String property that can be set by the child view. Then, when the parent view reappears, put that data into the text field, inside viewWillAppear: for example. You'd want to have the value set to some default value for when the parent view initially shows up too.
-(void) viewWillAppear:(BOOL) animated doesn't get called for me either, exactly when it's a modal view controller. No idea why. Not incorrectly overridden anywhere in this app, and the same problem occurs on the other 2 apps I'm working on. I really don't think it works.
I've used the delegate approach before, but I think that following approach is pretty good as well.
I work around this by adding a private category to UIViewController, like so:
.h file:
#interface UIViewController(Extras)
// returns true if this view was presented via presentModalViewController:animated:, false otherwise.
#property(readonly) BOOL isModal;
// Just like the regular dismissModalViewController, but actually calls viewWillAppear: on the parent, which hasn't been working for me, ever, for modal dialogs.
- (void)dismissModal: (BOOL) animated;
#end
and .m file:
#implementation UIView(Extras)
-(BOOL) isModal
{
return self == self.parentViewController.modalViewController;
}
- (void)dismissModal: (BOOL) animated
{
[self.parentViewController viewWillAppear: animated];
[self dismissModalViewControllerAnimated: animated];
}
#end
which I can now call like this when I want to dismiss the dialog box:
// If presented as a modal view, dismiss yourself.
if(self.isModal)
[self dismissModal: YES];
and now viewWillAppear is correctly called.
And yes, I'm donating a bonus 'isModal' property, so that the modal view can tell how it was being presented, and dismiss itself appropriately.