I've looked all over, and found many people with similar problems, but I still can't get my delegates working. I want to make a model view controller pop up, then call a method in the view that made the model view asking it to dismiss it. So I have this line:
mergeConfig *view = [[mergeConfig alloc] initWithNibName:#"mergeConfig" bundle:nil];
and I'm trying [view setDelegate:self]; as said to on apple's developer pages, but expectably my model view doesn't have a setDelegate method.
So what I want to know is, how do I get it so that I can set a delegate? And then once I do, does it just automatically pass calls to methods to methods in the parent view with the same name? Apple's pages didn't say what code to put in the model view controller.
You need to define a delegate on your custom view controller, as such:
#interface mergeConfig {
id delegate;
}
#property (nonatomic, assign) id delegate;
#end
#implementation mergeConfig
#synthesize delegate;
#end
Then, elsewhere in the class for your view controller you can invoke whatever methods you need on your delegate.
Personally I like to improve the above by defining a protocol that my delegates comply to, as follows:
#protocol MyDelegateProtocol
- (void)delegateMethod;
#end
#interface mergeConfig {
id<MyDelegateProtocol> delegate;
}
#property (nonatomic, assign) id<MyDelegateProtocol> delegate;
#end
#implementation mergeConfig
#synthesize delegate;
#end
If you simply need to dismiss the modal view controller, just call [self.parentViewController dismissModalViewControllerAnimated:YES]; at the appropriate time. No need for delegates unless you need to pass information back up the chain.
Related
Thanks in advance for your help!
In the main ViewController.m of my project I am adding a customized tableView like so:
messageController = [[MyMessagesController alloc] initWithStyle:UITableViewStylePlain];
[self addChildViewController:messageController];
[self.view addSubview:messageController.view];
Then, in the MyMessagesController.m section tableView didSelectRowAtIndexPath: I'd like to write code that would take effect in the ViewController.m where it was created and added as a childViewController.
How can I access the functions of the ViewController.m from MyMessagesController.m?
Can I make it a delegate somehow so I could call [delegate functionName];?
Could I pass information back to the ViewController.m? About which of the rows in table was selected by sending through an NSString or NSArray or anything?
Yes, use a delegate, if you are unsure how best to accomplish this, here is a good reference from Apple about delegate programming
Got it figured out, here's how you turn one viewController into a delegate for another:
In the .h of the parent controller -
#interface ViewController : UIViewController <NameOfDelegate> {
In the .m of the parent controller, once you create the new view -
newViewController.delegate = self;
and also:
- (void)functionToCall:(id)sender {
NSLog(#"Function Called!!!");
}
In the .h of the newViewController you're adding -
#protocol NameOfDelegate;
#interface newViewController : UIViewController/OR/TableViewController {
id <NameOfDelegate> delegate;
}
#property (nonatomic, strong) id <NameOfDelegate> delegate;
#end
#protocol NameOfDelegate
- (void)functionToCall:(id)sender;
#end
in the .m of the newViewController -
#implementation newViewController
#synthesize delegate;
and when you're ready to call the function in your delegate -
[delegate functionToCall:self];
I'm a relatively new iPhone developer and am making great progress building my 2nd iPhone app. In the app I'm building now I'm doing some code separation with some protocols and delegates so that I car re-use some of my code in a variety of places throughout my code.
Here's what I want to happen:
CITRootViewController creates an instance of a CITReportCreator class, passing itself as a property so that the reportCreator can open additional view controllers and such.
CITReportCreator class is declared as implementing the CITImageCaptureDelegate protocol, which is declared in the CITImageCaptureViewController file.
CITImageCaptureViewController defines the delegate protocol and has a method that passes back data and references to the child view controller so that CITReportCreator can interact with it's data, close the related XIB, etc.
I believe I'm getting the delegate and protocol established correctly, and verified that my 'delegate' object still contains data when it is called, but I'm getting a EXC_BAD_ACCESS method when my view controller tries to pass data back to the delegate in this line of code:
[self.delegate childViewControllerDidFinish:self];
Here's a good portion of the rest of my code. I had this working by using CITRootViewController as my delegate instead of the CITReportCreator class, but now that I'm separating the code, something has broke.
CITReootViewController.m (the view controller that calls the Report Creator)
//create a nrew report
-(IBAction)createReport:(id)sender {
CITReportCreator *report = [CITReportCreator alloc];
[report createNewReport:self];
}
CITReportCreator.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "CITImageCaptureViewController.h"
#interface CITReportCreator : NSObject <CITImageCaptureDelegate>
#property (strong, nonatomic) NSArray *imageList;
#property (nonatomic) NSInteger imageIndex;
-(int) createNewReport:(UIViewController *)parent ;
//Delegate Methods
-(void) childViewControllerDidFinish:(UIViewController*)viewController;
#end
And CITReportCreator.m
#import "CITReportCreator.h"
#implementation CITReportCreator
{
UIViewController *parentController;
}
#synthesize imageList;
#synthesize imageIndex;
-(int) createNewReport:(UIViewController *)parent
{
//store a reference to the parent view controller
parentController = parent;
// init code....
//head to the first image capture view
[self startImageCapture];
return 0;
}
-(int)startImageCapture
{
//pull the image name from the array of images
NSString *imageName = [imageList objectAtIndex:imageIndex];
//prep the image capture controller
CITImageCaptureViewController *capture = [[CITImageCaptureViewController alloc] initWithNibName:#"CITImageCaptureViewController" bundle:nil];
//Assign the capture controller's delegate
capture.imageName = imageName;
capture.delegate = self;
//Display the capture controller
[parentController presentModalViewController:capture animated:YES];
return 0;
}
//a break point set here never gets hit.
-(void) childViewControllerDidFinish:(UIViewController*)viewController;
{
[viewController dismissModalViewControllerAnimated:YES];
}
#end
And finally, the CITImageCaptureViewControllers
CITImageCaptureViewController.h
#import <UIKit/UIKit.h>
#protocol CITImageCaptureDelegate <NSObject>
-(void) childViewControllerDidFinish:(UIViewController*)viewController;
#end
#interface CITImageCaptureViewController : UIViewController
{
id<CITImageCaptureDelegate> delegate;
}
#property (nonatomic,assign) id<CITImageCaptureDelegate> delegate;
#property (nonatomic, assign) NSString *imageName;
//continue button pressed method
-(IBAction)continueButtonPressed:(id)sender;
#end
And the .m file
#import "CITImageCaptureViewController.h"
#interface CITImageCaptureViewController ()
#end
#implementation CITImageCaptureViewController
#synthesize navItem;
#synthesize imageName;
#synthesize delegate = _delegate; //i think this may be part of the problem
//cutting out initWithNibName, viewDidLoad, etc...
- (IBAction)continueButtonPressed:(id)sender
{
[self.delegate childViewControllerDidFinish:self];
}
#end
I find nothing with delegates and protocols all that simple, but I'm guessing I'm missing a small change somewhere. Can you help me head in the right direction?
I am building a utility-based application, the data is stored in the MainViewController, and now I know how to pass data to the FlipsideViewController (many regards to this thread BTW, Sending data from Mainview to Flipside?). But I am getting the data onto an subview (subclass of UIView) that I have added to the flipside view. How can I pass data to this subview? I saw there is already a delegate and protocol set up in the FlipsideViewController.h, I am really new to the delegate sort of things. Any help would be greatly appreciated!
Updates:
On the main view, I have a couple of text fields for users to input to create an object. All the objects are stored in an array. Namely, my data is created and stored in the MainViewController. Now on the flip side, I have a custom UIView subclass which allows me to do my own drawing based on the data in that array. What I need to do here is pass the data that stored in MainViewController to this subview. Here is my relevant code:
In the MainViewController.m
- (IBAction)showInfo:(id)sender {
FlipsideViewController *controller = [[FlipsideViewController alloc] initWithNibName:#"FlipsideView" bundle:nil];
controller.delegate = self;
controller.receiver = data;//this is what I've done.
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:controller animated:YES];
[controller release];
}
In the FlipsideViewController.h
#protocol FlipsideViewControllerDelegate;
#interface FlipsideViewController : UIViewController {
id <FlipsideViewControllerDelegate> delegate;
DataModel *receiver; //create a property to receive the data transferred from main view
}
#property (nonatomic, assign) id <FlipsideViewControllerDelegate> delegate;
#property (nonatomic, retain) DataModel *receiver;
- (IBAction)done:(id)sender;
#end
#protocol FlipsideViewControllerDelegate
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller;
#end
In the above code, "data" is an DataModel object declared in the MainViewController.h file.
And I want to do my custom drawing in drawing class (subclass of UIView), how can I pass data from the FlipsideViewControllerto this subview? Do I need to make use of delegate declared in the FlipsideViewController.h file? Thanks in advance!
I have had a quick look at the template and think you are getting confused with what the delegate is being used for.
The delegate in this template is not transferring data. When you have clicked the done button it calls back to MainViewController and asks it to call the dismissModalViewControllerAnimated method so that it can remove the view controller. This seems a bit superflous as the documentation states
If you call this method on the modal view controller itself, however, the modal view controller automatically forwards the message to its parent view controller.
Therefore you don't really need to call the parent to do this.
In Interface builder you can see that the FlipsideView.xib has it's File's Owner set to FlipsideViewController.xib.
Now if you right click the File's Owner you will see that view is connected to View this basically means that view is the name of the property in FlipsideViewController and View is the element in Interface Builder.
Therefore we can access elements in the xib file from FlipsideViewController using outlets.
To say draw a label you will need to do a couple of things
First add a property in the .h and synthesize it in the .m like
// FlipsideViewController.h
#interface FlipsideViewController : UIViewController
#property (nonatomic, retain) IBOutlet UILabel *testLabel; // <----- Added this
#property (nonatomic, assign) id <FlipsideViewControllerDelegate> delegate;
- (IBAction)done:(id)sender;
#end
// FlipsideViewController.m
#implementation FlipsideViewController
#synthesize delegate = _delegate;
#synthesize testLabel = _testLabel; // <----- Added this
// More methods
- (void)dealloc
{
[_testLabel release]; // Always do you memory management
[super dealloc];
}
Then back in Interface Builder
Add a UILabel element to your view
ctrl + drag from File's Owner to the UILabel you added
Select the label in my example it is testLabel
Now these are hooked up correctly. The place where you want to be setting the value of the label is in viewDidLoad: which you can now do like this
- (void)viewDidLoad
{
[super viewDidLoad];
self.testLabel.text = #"It Works"; // You would use the data passed in from `MainViewController`
}
I find the easiest way to pass data from one view to another is by directly setting the data in the next view from the original view.
For example;
In your FlipsideViewController.h, declare a 'container' for the data you want to pass. It must be the same class on both sides to work properly, ie. NSArray to NSArray, NSMutableDictionary to NSMutableDictionary.
NSMutableArray *newData;
...
#property (nonatomic, retain) NSMutableArray *newData; // This allows you to access this object from outside this class.
and in FlipsideViewController.m
#synthesize newData;
...
[newData release];
Now we need to pass the data, so to speak. Let's say the data we want to 'send' is stored in a NSMutableArray called 'results'.
In our MainViewController.m, when we are instantiating our next view controller (in this case FlipsideViewController) we can directly reference the newData mutable array after we initalize the nib.
FlipsideViewController *controller = [[FlipsideViewController alloc] initWithNibName:#"FlipsideView" bundle:nil];
controller.newData = results;
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:controller animated:YES];
[controller release];
Make sure you are importing your FlipsideViewController in your MainViewController.h file.
If the property is declared in your .h file, you can pretty much reference the contents of the object from anywhere within the view stack!
Hope that helps :D
This is probably a noob question but can't get my head around it.
How do i make a connection between 2 viewcontrollers or a view controller and my appdelegate?
what i usually do is add the following to my app delegate "h" file
#class RootViewController;
#interface TabBarWithSplitViewAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> {
RootViewController *rootViewController;
}
#property (nonatomic, retain) IBOutlet RootViewController *rootViewController;
#end
and then create a connection in the Interface Builder. from my root view controller to the app delegate and automatically tells me thats the rootViewController that i added above.
and if you do this on the app delegate "m" file:
#import "RootViewController.h"
NSLOG(#"Controller %#",rootViewController);
it gives you a bunch of numbers indicating that there is a connection
But as you know with xcode 4 this changed since you usually no longer have the main.xib where you can create the connection, you do almost all those connections programatically.
i`ve tried everything from using the same code without the "IBOutlet" to adding:
rootViewController = [[RootViewController]alloc] init;
but nothing seems to work.
can anybody help out?
Thanks in advance
You will basically want to create an ivar of your view controller in your app delegate.
ViewController *myVC;
#property (nonatomic, retain) IBOutlet ViewController *myVC;
then synthesize it in the implementation file.
Then when the view controller loads, call something along the lines of this:
- (void)viewDidLoad {
AppDelegateClass *appDelegate = (AppDelegateClass *)[[UIApplication sharedApplication] delegate];
appDelegate.myVC = self;
}
At this point, you now have a direct connection to your view controller from the app delegate. Similarly, you could do the opposite to call app delegate methods from the view controller. In that case, you'd set up a delegate in the view controller's header.
id delegate;
#property (nonatomic, assign) id delegate;
again synthesizing it in the implementation file.
Now when you are in viewDidLoad, you'd call something like this:
- (void)viewDidLoad {
self.delegate = (AppDelegateClass *)[[UIApplication sharedApplication] delegate];
}
That should give you what you need to get going, so I hope that helps
You can do this with interface builder in XCode 4. I have made a short video on how to do it:
http://www.youtube.com/watch?v=6VOQMBoyqbA
I am trying to call up a modal table view controller using presentModalViewController but I am not sure what to do about the delegate. The following code gives me an error:
MyRidesListView *controller = [[MyRidesListView alloc] init];
controller.delegate = self;
[self presentModalViewController:controller animated:YES];
[controller release];
Error:
Request for member 'delegate' is something not a structure or union
Now, I realized there is no delegate property in my MyRidesListView class. So, how would I add a reference to my delegate there? What am I missing here?
Generally delegates are properties defined as such:
id<NameOfDelegateProtocol> delegate;
And:
#property (nonatomic, assign) id<NameOfDelegateProtocol> delegate;
EDIT: You said your parent class is UITableViewController. You may have wanted to do this:
controller.tableView.delegate = self;
Why do you think you need a delegate? Why not just remove the "controller.delegate = self" line. Otherwise you need to implement a delegate system the way I outline below or else make MyRidesListView a subclass of a viewcontroller that implements delegates.
It looks like you cut and pasted some sample code that uses a delegate, then substituted your own viewcontroller that doesn't provide a delegate. If you don't know what the delegate is for, then just delete that line.
I'll cut and paste some actual code from one of my test programs to show you how it's done:
from the Interface file:
Add a delegate instance variable to your class and make it a property so you can use the "blah.delegate = foo" syntax to set it.
#interface BAPClient : NSObject {
CGSize imageSize;
id <BAPClientDelegate> delegate;
}
#property (nonatomic, readonly) CGSize imageSize;
#property (nonatomic, assign) id <BAPClientDelegate> delegate;
#end
// define the protocol spoken. (what the delegate must implement)
#protocol BAPClientDelegate
- (void)addTile:(BAPTile *)tile;
#end
in the implementation, you must call the delegate at the appropriate time:
- (void)deliverTile:(BAPTile *) tile {
NSLog(#"%s tile=%p",__FUNCTION__,tile);
if ([self delegate])
[[self delegate] addTile:tile];
[tile release];
}
Try to set the delegate object by the setter
[controller setDelegate:self];
This often works wonders.