I'm working on an iPad App and i'm having issue with delegate... the protocol method does not get invoked. i'm not sure what i'm missing, here is my code.
#protocol pickerLabelProtocol <NSObject>
- (void)selectedPickerData:(UILabel *)sender;
#end
#interface showPickerVC : UIViewController
#property (nonatomic, strong) id <pickerLabelProtocol> delegate;
#end
#implementation showPickerVC
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
//i used breakpoint, the 'delegate' is always nil for some reason?
[self.delegate selectedPickerData:self.mainLabel];
}
----------------------
#interface someViewController : UIViewController <pickerLabelProtocol>
#property (nonatomic, strong) showPickerVC *showPicker;
#end
#implementation someViewController
- (void)selectedPickerData:(UILabel *)sender
{
//protocol method
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.showPicker = [[showPickerVC alloc]init];
self.showPicker.delegate = self;
}
I can not got any mistake From your code but i suggest you that Be clear about when you create object of showPickerVC add it's delegate self
Such Like ,
showPickerVC *obj = [[showPickerVC alloc] init];
obj.delegate = self; /// YOur protocol delegate
.
.
[self presentModalViewController:obj animated:YES];
And Also add code as following
#implementation showPickerVC
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
if([self.delegate respondsToSelector:#selector(selectedPickerData:)])
{
[self.delegate selectedPickerData:self.mainLabel];
}
}
For More information about How to create/use of Protocol.
Related
I started testing ECSlidingViewController and after I tried to access FirstTopViewController I have a big trouble - because in FirstToViewController I already have ZBarReaderDelegate implemented and all examples of delegate are not triggering any method from my delegate.
Basically I have this stuff:
FirstTopViewController.h
#import ...MyStuff...
#import "UnderRightViewController.h"
#interface FirstTopViewController : UIViewController <RightViewDelegate, ZBarReaderDelegate>
#property (weak, nonatomic) IBOutlet UITextView *labelTotal;
#end
FirstTopViewController.m
#import "FirstTopViewController.h"
#implementation FirstTopViewController
- (void)setTotalViewController:(UnderRightViewController*)controller didTotalChange:(NSString*)total
{
//labelTotal.text = total;
NSLog(#"I'm here!!! and received %#", total);
}
From other side I have
UnderRightViewController.h
#import <UIKit/UIKit.h>
#import "ECSlidingViewController.h"
#class UnderRightViewController;
#protocol RightViewDelegate <NSObject>
- (void)setTotalViewController:(UnderRightViewController*)controller didTotalChange:(NSString*)total;
#end
#interface UnderRightViewController : UITableViewController
#property (nonatomic, weak) id <RightViewDelegate> delegate;
#end
UnderRightViewController.m
#import "UnderRightViewController.h"
#interface UnderRightViewController ()
#end
#implementation UnderRightViewController
#synthesize delegate;
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[delegate setTotalViewController:self didTotalChange:#"foo"];
}
#end
I'm trying this entire day solve this puzzle but I never get setTotalViewController fired.
Thanks in advance.
Friend you did a small mistake, when you navigate from FirstTopViewController to UnderRightViewController at that time you need to do this in FirstTopViewController.m:-
UnderRightViewController *obj = [[UnderRightViewController
alloc] initWithNibName:#"UnderRightViewController" bundle:nil];
obj.delegate = self; // u forget to assign protocol handler
[self.navigationController pushViewController:obj animated:YES];
[obj release];
You don't have any code that is setting the delegate for the UnderRightViewController. I don't know what object owns both of these controllers, but before either UnderRightViewController and FirstTopViewController are displayed it should run code something like this:
FirstTopViewController *ftvc = //... where ever you get a reference to this from
UnderRightViewController *urvc = ...;
urvc.delegate = ftvc;
In your above code you are using custom delegates and also you have used it for sending message to onecontroller class to another controller class. So below is the same sample code of custom delegates, it is working fine in similar way you have to implement and also the problem in your code is you are not setting the delegate, so please follow below how to set the same and call the method. here i have used your same method only return type i have defined as NSString in-spite of void for explaining purpose, but you can use void according to your requirement hope it will be helpful to you:-
First Controller Class AWindowController.h
#interface AWindowController : NSWindowController<sampleDelegate>
{
NSString *textA;
}
#property(readwrite,retain)NSString *textA;
-(IBAction)doSet:(id)sender;
#end
#import "AWindowController.h"
#import "BWindowController.h"
#interface AWindowController ()
#end
#implementation AWindowController
#synthesize textA;
- (id)initWithWindow:(NSWindow *)window
{
self = [super initWithWindow:window];
if (self) {
// Initialization code here.
}
return self;
}
- (NSString *)setTotalViewController:(BWindowController*)controller didTotalChange:(NSString*)total
{
NSLog(#"recieved");
return #"recieved";
}
- (void)windowDidLoad
{
[super windowDidLoad];
// Implement this method to handle any initialization after your window controller's window has been loaded from its nib file.
}
-(NSString*)windowNibName
{
return #"AWindowController";
}
-(IBAction)doSet:(id)sender
{
[self setTextA:#"Awindow Button Pressed"];
BWindowController *b=[[BWindowController alloc]init];
b.delegate=self;
[b showWindow:self];
}
#end
Second Controller Class BWindowController.h
#import <Cocoa/Cocoa.h>
#import "sampleDelegate.h"
#class BWindowController;
#protocol sampleDelegate <NSObject>
#required
//-(NSString *)getDataValue;
- (NSString *)setTotalViewController:(BWindowController*)controller didTotalChange:(NSString*)total;
#end
#interface BWindowController : NSWindowController<sampleDelegate>
{
NSString *bTextValue;
id<sampleDelegate>delegate;
}
#property(readwrite,retain)NSString *bTextValue;
#property(readwrite,assign)id<sampleDelegate>delegate;
#end
#import "BWindowController.h"
#interface BWindowController ()
#end
#implementation BWindowController
#synthesize bTextValue,delegate;
- (id)initWithWindow:(NSWindow *)window
{
self = [super initWithWindow:window];
if (self) {
// Initialization code here.
}
return self;
}
- (NSString *)setTotalViewController:(BWindowController*)controller didTotalChange:(NSString*)total;
{
return nil;
}
- (void)windowDidLoad
{
NSString *str= [[self delegate]setTotalViewController:self didTotalChange:#"recieved"];
self.bTextValue=str;
[super windowDidLoad];
// Implement this method to handle any initialization after your window controller's window has been loaded from its nib file.
}
-(NSString*)windowNibName
{
return #"BWindowController";
}
#end
Attached screen shot in Output:-
Below is window is the AwindowController.h class
Below in the same above window pressing the button and when Awindow button pressed data will send
and notification will be recieved in Bwindow using above define custom delegates as attached in the screen shot.
I am a newbie to iOS world, so please ignore the obvious.
I am pushing a viewController(HelpViewController) on top of another viewController(MainViewController). When a particular action happens in the HelpViewController, I would like to update a variable inside the MainViewController. I understand for this I need to use delegate.
Here is my delegate header...
#protocol ViewControllerDelegate <NSObject>
#required
- (void) switchToggled:(BOOL)status;
#end
// Protocol Definition ends here
#interface ViewDelegate : NSObject
{
// Delegate to respond back
id <ViewControllerDelegate> _delegate;
}
#property (nonatomic,strong) id delegate;
-(void)sendMessage:(BOOL)status; // Instance method
#end
and implementation...
#implementation ViewDelegate
#synthesize delegate;
-(id)init {
self = [super init];
return self;
}
-(void)sendMessage:(BOOL)status
{
[delegate switchToggled:status];
}
- (void)dealloc
{
[super dealloc];
}
#end
So Now If I want to implement Protocol ViewControllerDelegate I need to specify in MainViewController, which I do as follows --
MainViewController <ViewControllerDelegate>
and
#pragma mark - ViewControllerDelegate delegate
-(void)switchToggled:(BOOL)status{
NSLog(#"Switch Toggled(%d) Message passed to MainViewController",status);
}
My question is how do I specify Object, which delegate property needs to point to, so that it can come back to MainViewController's "switchToggled".
One way I do is by having property inside HelpViewController as follows -
MainViewController.m
HelpViewController *helpVC = [[HelpViewController alloc] init];
helpVC.mainView = self;
[self.navigationController pushViewController:helpVC animated:YES];
[helpVC release];
HelpViewController.h
#property (nonatomic) MainViewController *mainView;
HelpViewController.m
#synthesize mainView;
ViewDelegate *myDelegate = [[ViewDelegate alloc] init];
// assign delegate
myDelegate.delegate = mainView;
[myDelegate sendMessage];
[myDelegate release];
Is this correct way to implement or there is better way to achieve this or am I totally wrong.
Thanks
You should do:
// HelpViewController.h
#protocol HelpDelegate
- (void)switchToggled:(BOOL)status;
#end
// HelpViewController.m
#interface HelpViewController : UIViewController
#property (nonatomic, assign) id<HelpDelegate> delegate;
- (id)initWithDelegate:(id<HelpDelegate>)delegate
#end
#implementation HelpViewController
- (id)initWithDelegate:(id<HelpDelegate>)delegate
{
if (self = [super init])
{
self.delegate = delegate;
}
}
- (void)sendMessage:(BOOL)status
{
[self.delegate switchToggled:status];
}
// MainViewController.h
#import "HelpViewController.h"
#interface MainViewController.h : UIViewController <HelpDelegate>
// MainViewController.m
- (void)someMethod
{
HelpViewController* viewController;
viewController = [HelpViewController alloc] initWithDelegate:self];
...
}
#pragma mark - Help Delegate
- (void)switchToggled:(BOOL)status
{
...
}
Give the delegate a name that makes clear to which class it belongs.
You don't need the extra class/files for ViewDelegate/ViewControllerDelegate. Just define the delegate in header of class it belongs to: HelpViewController.n in this case.
Similar: Implement the delegate method switchToggled: in the real class MainViewController, and not in the extra/unnecessary class ViewDelegate.
The purpose of delegates is to avoid class dependencies. By including MainViewController in HelpViewController you create such a dependency. This is not necessary as I show, and is wrong design.
You were also creating a circular dependency, because MainViewController already needed HelpViewController in order to show it, and now they need each other the other way around for sending the event.
Alternatively you can make HelpViewController's delegate public, have an init without argument, and expect users to set it with helpViewController.delegate = self; or something. But this would only make sense when the delegate being set is optional (which don't seems the case here, so adding it to the init method is appropriate).
I tell you what I would have done:
1) the protocol definition is ok, but do NOT create the class ViewDelegate, so:
//ViewControllerDelegate.h
#protocol ViewControllerDelegate <NSObject>
#required
- (void) switchToggled:(BOOL)status;
#end
2) Your implementation of the delegate method in MainViewController is ok.
3) Now... the important point:
//interface
#interface HelpViewController : UIViewController //or whatever superclass..
{
id <ViewControllerDelegate> _delegate;
}
#property (nonatomic,strong) id<ViewControllerDelegate> delegate;
#end
//implementation
#implementation HelpViewController
- (void)someMethodWhichCallsTheDelegate
{
//do something
...
// call delegate
//if switchToggled: were optional then add the following
//if ([self.delegate respondToSelector:#selector(switchToggled:)]) {
[self.delegate switchToggled:status];
}
#end
4) Now you have to assign the delegate:
//MainViewController.m
HelpViewController *helpVC = [[HelpViewController alloc] init];
helpVC.delegate = self;
[self.navigationController pushViewController:helpVC animated:YES];
[helpVC release];
And that's it!
BTW: if this delegate is related only to HelpViewControllerthen add the protocol definition where you define the interface of the class, it is not necessary to create a separate header file. If instead the protocol is "global", then it can have some sense to declare it separately.
I want to make a library that I can reuse over and over to speed up my development, add to new projects if I wish. Basically I want to build an abstraction layer. Can someone show me how I would do that and why this this portion of code:
if ([self.delegate respondsToSelector:#selector(enableCamera)]) {
BOOL enabled;
enabled = [self.delegate enableCamera];
if (enabled == YES) {
[self enableCameraMethod];
}
does not get called?
HERES MY CODE BELOW:
library.h:
#protocol usesCamera <NSObject>
#optional
-(BOOL)enableCamera;
#end
#interface Library : NSObject
#property (nonatomic, weak) id <usesCamera> delegate;
-(void)enableCameraMethod;
#end
library.m
#import "Library.h"
#implementation Library
- (id) init
{
if (self = [super init]) {
if ([self.delegate respondsToSelector:#selector(enableCamera)]) {
BOOL enabled;
enabled = [self.delegate enableCamera];
if (enabled == YES) {
[self enableCameraMethod];
}
}
return (self);
}
}
-(void)enableCameraMethod {
NSLog(#"Implement my camera method here");
}
#end
UIViewController.h
#import <UIKit/UIKit.h>
#import "Library.h"
#interface ViewController : UIViewController <usesCamera>
#end
UIViewController.m
#import "ViewController.h"
#import "Library.h"
#interface ViewController ()
#property (nonatomic, strong) UIViewController *myVC;
#end
#implementation ViewController
-(BOOL)enableCamera {
return YES;
}
- (void)viewDidLoad
{
[super viewDidLoad];
Library *myLibrary = [[Library alloc] init];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
did you set your delegate for myLibrary instance in your ViewController class.
you have to do something like this:
Library *myLibrary = [[Library alloc] init];
myLibrary.delegate = self;
As init is called before setting the delegate, so it might not worked, instead of defining the logic in init function create another method and call this method after setting the delegate.
Hi I have two viewControllers.
NewsViewController
#import "SingleViewController.h"
#interface NewsViewController : UIViewController {
}
- (NSString *)getFirstImage:(NSString *)htmlString;
#end
and the implementation file:
#import "SingleViewController.h"
SingleViewController *singleViewController;
#interface NewsPadViewController () <UIActionSheetDelegate>
- (void)loadSubscriptions;
#property (nonatomic, assign) BOOL wrap;
#property (nonatomic, retain) NSMutableArray *items;
#end
#implementation NewsPadViewController
....CODE....
- (void)carouselCurrentItemTapped{
//[self addSubview:articolo];
MWFeedItem *item =[reader.feedItems objectAtIndex:[carousel currentItemIndex]];
NSLog(#"Current Item tappped, index: %d", [carousel currentItemIndex]);
singleViewController.prova.text=#"CIAO";
singleViewController.ciao=#"sample";
[singleViewController.web loadHTMLString:item.summary baseURL:nil];
NSLog(#"conternutio:");
NSLog(singleViewController.ciao);
}
SingleViewController.h
#import <UIKit/UIKit.h>
#interface SingleViewController : UIViewController{
#public
UIWebView *web;
UILabel *prova;
NSString *ciao;
}
#property (nonatomic,retain) IBOutlet UIWebView *web;
#property (nonatomic,retain) IBOutlet UILabel *prova;
#property (nonatomic,retain) IBOutlet NSString *ciao;
#end
and SingleViewController.m
#import "SingleViewController.h"
#implementation SingleViewController
#synthesize web,prova,ciao;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[prova setText:ciao];
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#end
Why I can't access from NewsPadViewController at object in SingleViewController? Where is my error? thanks
UPADATE
- (void)carouselCurrentItemTapped{
//[self addSubview:articolo];
MWFeedItem *item =[reader.feedItems objectAtIndex:[carousel currentItemIndex]];
NSLog(#"Current Item tappped, index: %d", [carousel currentItemIndex]);
SingleViewController *singleViewController = [[SingleViewController alloc] initWithNibName:#"SingleViewController" bundle:[NSBundle mainBundle]];
singleViewController.prova.text=#"CIAO";
singleViewController.ciao=#"sample";
[singleViewController.web loadHTMLString:item.summary baseURL:nil];
NSLog(#"conternutio:");
NSLog(singleViewController.ciao);
[singleViewController setOpz:#"sample"];
}
I don't see any instantiation of SingleViewController. You have a pointer to it, but I don't see anywhere in your code example where you actually create it.
Somewhere you need something like:
if (!singleViewController) {
singleViewController = [[SingleViewController alloc] init];
}
or
SingleViewController *singleViewController = [[SingleViewController alloc] initWithNibName:#"SingleView" bundle:nil];
or from somewhere else you need to send a message or set an instance variable in NewsViewController that points to an existing instance of SingleViewController.
I'm developing an application.
I used a TabBar and every tab have its Class (FirstViewController, SecondViewController, ... )
There is one AppDelegate too.
When I launch the program, the first Class is running.
When i select the second tab, the Secondview.xib 's running but the "viewDidLoad" isn't working.
When I select the third Tab, that's the same.
I've put some buttons on the third tab, and when I push it, I have a
> -[UIViewController testAuthentication:]: unrecognized selector sent to instance 0x5f16920
2011-04-08 13:46:42.511 e-mars[19501:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIViewController testAuthentication:]: unrecognized selector sent to instance 0x5f16920'
Here's the code of my classes
SecondViewController.h
#import <UIKit/UIKit.h>
#interface SecondViewController : UIViewController {
}
#end
SecondViewController.m
#import "SecondViewController.h"
#implementation SecondViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSLog(#"viewDidLoad de SecondViewController");
NSURL *url = [NSURL URLWithString: #"http://iosdevelopertips.com/images/logo-iphone-dev-tips.png"];
UIImage *image = [UIImage imageWithData: [NSData dataWithContentsOfURL:url]];
[self.view addSubview:[[UIImageView alloc] initWithImage:image]];
}
- (void)dealloc {
[super dealloc];
}
#end
ThirdViewController.h
#import <UIKit/UIKit.h>
#interface ThirdViewController : UIViewController {
IBOutlet UITextField *login;
IBOutlet UITextField *motdepasse;
NSMutableData *responseData;
}
#property (retain, nonatomic) UITextField *login;
#property (retain, nonatomic) UITextField *motdepasse;
#property (retain, nonatomic) NSMutableData *responseData;
- (IBAction) testAuthentication: (id)sender;
- (IBAction) saveAuthentication: (id)sender;
#end
ThirdViewController.m
#import "ThirdViewController.h"
#implementation ThirdViewController
#synthesize login;
#synthesize motdepasse;
#synthesize responseData;
- (id)initWithFrame:(CGRect)frame {
//if ((self = [super initWithFrame:frame])) {
// Initialization code
//}
return self;
}
-(IBAction) testAuthentication: (id)sender {
//NSLog(#"testAuthentication");
}
- (IBAction) saveAuthentication: (id)sender {
NSLog(#"saveAuthentication");
}
- (void)dealloc {
[login dealloc];
[motdepasse dealloc];
[responseData dealloc];
[super dealloc];
}
#end
Your third ViewController doesn't actually create an instance, so no instance methods can be called upon it. Fix your initWithFrame: method. Remember: instance methods start with the '-' sign, class methods start with the '+' sign.
- (id)initWithFrame:(CGRect)frame {
self = [super initWithNibName:nil bundle:nil];
if (self)) {
// Initialization code
}
return self;
}
- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle
{
return [self initWithFrame:CGRectZero];
}
- (id)init
{
return [self initWithFrame:CGRectZero];
}
After you fixed this, at least the viewDidLoad method in the third ViewController should work.
With regards to the second ViewController, could you please show the code you use to instantiate the ViewController?
Edit: I've made some changed to make sure initWithFrame: is always called upon initialization, just in case you create the instance using another method (initWithNibName:bundle: or init), now initWithFrame: has become the designated initializer.
Set class in Viewcontroller.
and then try.
Check the Object On which your are calling testAuthentication
May be you are calling testAuthentication on secondViewController's object , Just check and let us know
First time alone the viewController will come from viewDidLoad after that it does not call viewDidLoad instead it calls viewWillAppear. so you can code whatever you want in viewWillAppear.