Delegate declaration
// FolderListViewController.h
#import <UIKit/UIKit.h>
#import "Folder.h"
#protocol FolderSelectionDelegate <NSObject>
#required
- (void)setFolder:(Folder *)folder;
#end
#interface FolderListViewController : UITableViewController
#property (nonatomic, assign) id<FolderSelectionDelegate> delegate;
- (IBAction)showDashboard:(id)sender;
#end
Delegate is called from didSelectRowAtIndexPath:
// FolderListViewController.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[self.delegate setFolder:dataSource[indexPath.row]];
}
The VC that should be receiving the message
#import <UIKit/UIKit.h>
#import "FolderListViewController.h"
#import "Folder.h"
#interface ProjectListViewController : UITableViewController <FolderSelectionDelegate, UISplitViewControllerDelegate, UISearchBarDelegate, UINavigationControllerDelegate>
#property (nonatomic,retain)UIActivityIndicatorView *activityIndicatorObject;
#property (nonatomic, copy)Folder *folder;
-(void)loadProjects:(Folder*)folder;
#end
Action that presents the VC
- (void)foldersButtonTapped {
UINavigationController *vc = [[UIStoryboard storyboardWithName:#"MainStoryboard_iPhone" bundle:nil] instantiateViewControllerWithIdentifier:#"FolderListNavController"];
vc.delegate = self;
[self presentViewController:vc animated:YES completion:nil];
}
Delegate method implementation
- (void)setFolder:(Folder *)folder {
_folder = folder;
[self loadProjects:folder];
}
I have read through multiple threads on here and haven't had any luck. At first, I didn't have the reference to ProjectListVC setup when presenting the FolderListVC (ie, vc.delegate = self). That doesn't seem to be the problem here though. I am working on an app that was built for iPad and scaling it to work across all devices. The implementation as it is here works (it's setup as a split view controller). Any help would be greatly appreciated
I think that UINavigationcontroller is creating problem as it is not setting the FolderListViewController delegate . Can You try like this.
FolderListViewController *vc=[self.storyboard instantiateViewControllerWithIdentifier:#"FolderListViewController"];
vc.delegate=self; // protocol listener
[self.navigationController pushViewController:vc animated:YES];
Related
I'd like to trigger a message from viewController to another viewController.
And I coded like below, but viewController didn't call delegate.
I want to call delegate without stroyboard. I just want to send a message to another viewController.
viewController2.h
#protocol ViewController2Delegate;
#interface ViewController2 : UIViewController
#property (nonatomic, weak) id<ViewController2Delegate> delegate;
#end
#protocol ViewController2Delegate <NSObject>
- (void)showSomethingByDelegate;
#end
viewController2.m
#import "ViewController2.h"
#interface ViewController2 ()
#end
#implementation ViewController2
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (IBAction)buttonPressed:(id)sender {
[self.delegate showSomethingByDelegate];
}
#end
viewController.m
#import "ViewController.h"
#import "ViewController2.h"
#interface ViewController ()
<ViewController2Delegate>
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
ViewController2 *vc2 = [[ViewController2 alloc] init];
vc2.delegate = self;
}
// Below method was not called by delegate.
- (void)showSomethingByDelegate {
NSLog(#"Button Was Pressed!!!");
}
#end
well let me show an example more simple.
File: firstVC.h
/* This define the protocol object,
you can write methods required or optional the diference is when
the protocol is used in a class, xcode show you a yellow warning with required methods
like UITableViewDelegate, UITextFieldDelegate... */
#protocol firstVCDelegate <NSObject>
#required
- (void)didMessageFromOtherViewController: (NSString *)messageStr;
#optional
- (void)didOtherMessageNotRequired: (NSString *)messageStr;
#end
/* This is the definition of first UIViewController */
#interface firstViewController : UIViewController
#end
/* This is the definition of second UIViewController object with
a property that is our protocol 'firstVCDelegate' */
#interface secondViewController : UIViewController
#property (nonatomic, weak) id <firstVCDelegate> firstVCDelegate;
- (void)executeDelegateProcess;
#end
File: firstVC.m
#import "firstVC.h"
#pragma mark - First UIViewController with delegate
#interface firstViewController() <firstVCDelegate>
#end
#implementation firstViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Creating the 'secondViewController' object with delegate on this class
secondViewController *svc = [secondViewController new];
// Assign the delegate class
[svc setFirstVCDelegate: self];
// Run the delegate logic
[svc executeDelegateProcess];
}
- (void)didMessageFromOtherViewController:(NSString *)messageStr
{
// Receiving the message from the instance of our protocol in the 'secondViewController' class
NSLog(#"MESSAGE #1: %#", messageStr);
}
- (void)didOtherMessageNotRequired:(NSString *)messageStr
{
// Receiving the message in optional method
NSLog(#"MESSAGE #2: %#", messageStr);
}
#end
#pragma mark - Second UIViewController
#implementation secondViewController
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)setFirstVCDelegate:(id<firstVCDelegate>)firstVCDelegate
{
if (firstVCDelegate)
_firstVCDelegate = firstVCDelegate;
}
- (void)executeDelegateProcess
{
// This method is only for demo
// You can execute your delegate in the way you need to use
if (_firstVCDelegate) {
[_firstVCDelegate didMessageFromOtherViewController: #"Hello world, using the required method from secondViewController class"];
[_firstVCDelegate didOtherMessageNotRequired: #"Hello code using the optional method"];
}
}
#end
In your appDelegate.m in the method didFinishLaunchingWithOptions you can put this, and you need to #import "firstVC.h"
self.window = [[UIWindow alloc] initWithFrame: [[UIScreen mainScreen] bounds]];
self.window.autoresizesSubviews = YES;
[self.window makeKeyAndVisible];
[_window setRootViewController: [firstViewController new]];
Execute and see two logs messages, I hope I've helped :)
ViewController2 *vc2 = [[ViewController2 alloc] init];
This line of code is not doing what you think it is, this is creating a NEW instance of ViewController2 and storing it inside the variable vc2. At no point (based on your code) is this variable added to the navigation stack and displayed on screen.
Edit
Also as noticed by Holex, your vc2 variable will be removed from memory after the viewDidLoad is finished as you are not holding onto a reference of it. You would either need to create a property to hold onto it, or push it onto the navigation stack for the navigationController to hold onto it.
There are multiple ways to solve this issue:
Instead of creating a new viewController2, find a reference to the one already displayed on the screen (if it is on the screen).
If its not on the navigation stack, add vc2 to the navigation stack [self.navigationController pushViewController:vc2 animated:YES]; (assuming you have a navigation controller).
If not on the stack, and not intending to use a navigationController, present vc2 modally, such as [self presentViewController:vc2 animated:YES completion:nil];
I have three UIViewcontroller, namely ViewController, BViewController and CViewController, ViewController is RootViewController from UINavigationController,
I'm pushing from ViewController -> BViewController -> CViewController, through button action.
I have declared protocol in CViewController. This protocol method is working fine for BViewController, but I don't understand how to make work its delegate method in ViewController.
I had created an object of CViewController in View Controller, then declared self for that delegate, though its not working, Below is my code. Please help me. Where I'm doing wrong here !
My Root View Controller, namely ViewController
#import "ViewController.h"
#import "BViewController.h"
#import "CViewController.h"
#interface ViewController ()<testDelegates>
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
CViewController *cVC = [self.storyboard instantiateViewControllerWithIdentifier:#"CViewController"];
cVC.mydelegate = self;
}
- (IBAction)nextAction:(id)sender {
BViewController *bViewC = [self.storyboard instantiateViewControllerWithIdentifier:#"BViewController"];
[self.navigationController pushViewController:bViewC animated:YES];
}
-(void)TestMethod{
NSLog(#" Its NOT Working");
}
My Second View Controller, Namely BViewController
#import "BViewController.h"
#import "CViewController.h"
#interface BViewController ()<testDelegates>
#end
#implementation BViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (IBAction)bNextAction:(id)sender {
CViewController *cVC = [self.storyboard instantiateViewControllerWithIdentifier:#"CViewController"];
// cVC.mydelegate = self;
[self.navigationController pushViewController:cVC animated:YES];
}
-(void)TestMethod{
NSLog(#" Its Working If I uncomment to cVC.mydelegate = self");
}
And my third View Controller, Where i Declared a protocol in .h file, namely CViewController
#import <UIKit/UIKit.h>
#protocol testDelegates <NSObject>
-(void)TestMethod;
#end
#interface CViewController : UIViewController
#property (weak) id <testDelegates> mydelegate;
#end
And in .m file
#import "CViewController.h"
#interface CViewController ()
#end
#implementation CViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (IBAction)cNextAction:(id)sender {
[self.mydelegate TestMethod];
}
You create class and this class destroying after you leave viewDidLoad method.
- (void)viewDidLoad {
[super viewDidLoad];
CViewController *cVC = [self.storyboard instantiateViewControllerWithIdentifier:#"CViewController"];
cVC.mydelegate = self;
}
As I understand you need to perform some methods in the ViewController from the CViewController.
You can pass viewController as delegate from the BViewController and them past it to the CViewController.
Or you can use code like this:
- (IBAction)cNextAction:(id)sender {
id< testDelegates > delegate = self.navigationController.viewControllers[0];
if([delegate conformsToProtocol:#protocol(testDelegates)])
{
[delegate TestMethod];
}
}
This is no best way but it's will be work.
Try this
self.delegate = self.navigationController.viewControllers[0];
You need to declare a another Protocol into BViewController class.
Please follow below steps.
Step 1: BViewController.h
#protocol testDelegates2 <NSObject>
-(void)TestMethod2;
#interface BViewController : UIViewController
#property (weak) id <testDelegates> mydelegate;
#end
#implementation CViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (IBAction)cNextAction:(id)sender {
[self.mydelegate TestMethod2];
}
Step 2. In ViewController class conform Protocol
#interface ViewController ()<testDelegates>
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
CViewController *cVC = [self.storyboard instantiateViewControllerWithIdentifier:#"CViewController"];
cVC.mydelegate = self;
}
- (IBAction)nextAction:(id)sender {
BViewController *bViewC = [self.storyboard instantiateViewControllerWithIdentifier:#"BViewController"];
cVC.mydelegate = self; //important line
[self.navigationController pushViewController:bViewC animated:YES];
}
-(void)TestMethod2{
NSLog(#"Final Output");
}
If Your are trying to set Delegate of CViewController to ViewController then
try putting
self.mydelegate = self.navigationController.viewControllers[0]
on viewDidLoad method of CViewController.
Else you are Trying to make ViewController And BViewController both be Delegate of CViewController then this is not possible like this, as Delegate of a Object Can only be unique. This means the delegate is simply a variable which holds reference of object and as you know value to a variable can be unique at a instance of time.
So If you are willing to do some task on both Viewcontroller and BViewController then use notification pattern. See apple doc here
I have my first viewController "SFCrearMomentoViewController" and the second view is a tableViewController "MasterViewController". I need to select a row didSelectRowAtIndexPath and call the method didCelected which is implemented in my "first viewController" and close the view using dismissViewControllerAnimated.
The problem is that the method didCelected is never called. I've already tested this code in a test project using "two viewControllers" and it works but I don't know what's the problem in my current project.
SFCrearMomentoViewController.h
...
#import "MasterViewController.h"
#interface SFCrearMomentoViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate, UITextViewDelegate, MasterViewControllerDelegate>{
UIImagePickerController *picker;
}
...
SFCrearMomentoViewController.m
...
-(void)didSelected:(NSString *)nombre{
NSLog(#"didSelected method %#", nombre);
}
#end
MasterViewController.h
#import <UIKit/UIKit.h>
#protocol MasterViewControllerDelegate <NSObject>
#required
-(void) didSelected:(NSString *)nombre;
#end
#interface MasterViewController : UITableViewController
#property (weak, nonatomic) id <MasterViewControllerDelegate> delegate;
#end
MasterViewController.m
...
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[self.delegate didSelected:#"row selected"];
[self dismissViewControllerAnimated:YES completion:nil];
}
...
Solution: I had to set the delegate self. I implemented it in the Segue.
-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if ([segue.destinationViewController isKindOfClass:[MasterViewController class]]) {
MasterViewController *nextView = segue.destinationViewController;
nextView.delegate = self;
}
}
I had the same problem a few hours ago. In my case I set the delegate in prepareForSegue to the segue.destinationViewController but my destination view controller wasn't the View Controller with the delegate, it was a UINavigationController.
So I used this one:
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"modalNeuerRaum"])
{
[(MyCustomModalViewController*)[(UINavigationController*)segue.destinationViewController viewControllers][0] setDelegate:self];
}
}
That worked for me, but I don't know if you have a UINavigationController..
You need to set the delegate in SFCrearMomentoViewController, you can do it in viewDidLoad, for example.
masterViewController.delegate = self;
I assume that you allocated and initialised new masterViewController object of MasterViewController type.
In a view, let's call it firstView I created a secondView as follows and pushed it if certain thing happened in the firstView:
SecondViewController *secondVC = [[secondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
[self.navigationController pushViewController:secondVC animated:YES];
[secondVC release];
Now when I'm in the secondView if let say a button is pressed I want to go back to firstView and also pass back a value from secondView to the firstView (let say an integer value of a textfield from secondView to the firstView).
Here is what I tried:
#protocol SecondViewControllerDelegate;
#import <UIKit/UIKit.h>
#import "firstViewController.h"
#interface SecondViewController : UIViewController <UITextFieldDelegate>
{
UITextField *xInput;
id <SecondViewControllerDelegate> delegate;
}
- (IBAction)useXPressed:(UIButton *)sender;
#property (assign) id <SecondViewControllerDelegate> delegate;
#property (retain) IBOutlet UITextField *xInput;
#end
#protocol SecondViewControllerDelegate
- (void)secondViewController:(SecondViewController *)sender xValue:(int)value;
#end
And in the m file
- (IBAction)useXPressed:(UIButton *)sender
{
[self.delegate secondViewController:self xValue:1234]; // 1234 is just for test
}
And then in the firstView I did:
#import "SecondViewController.h"
#interface FirstViewController : UITableViewController <SecondViewControllerDelegate> {
}
#end
And implemented:
- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
[self.navigationController popViewControllerAnimated:YES];
}
Now, the problem is for one in FirstViewController I get the warning that "No definition of protocol "SecondViewControllerDelegate" is found, and for two the delegate method (last piece of code above) does not get invoked at all. Can somebody please tell me what's wrong?
After this line
SecondViewController *secondVC = [[secondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
Add
secondVC.delegate = self;
Also instead of
- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
[self.navigationController popViewControllerAnimated:YES];
}
You should use
- (void) secondViewController:(SecondViewController *)sender xValue:(int)value
{
[sender popViewControllerAnimated:YES];
}
In FirstViewController .h file :
#import "SecondViewController.h"
#interface FirstViewController : UITableViewController <SecondViewControllerDelegate> {
SecondViewController *secondViewController;
}
#end
In implementation file , where you init SecondViewController instance next line assign self to delegate property :
secondViewController.delegate = self;
Next define delegate method :
- (void)secondViewController:(SecondViewController *)sender xValue:(int)value
{
NSLog ("This is a Second View Controller with value %i",value)
}
For problem 1: The #protocol definition for SecondViewControllerDelegate looks like it's in secondViewController.h; are you sure this file is imported in firstViewController.h? Otherwise it won't know about the protocol.
Problem 2: It might be totally unrelated to problem 1. Are you sure the action is hooked up properly? Can you put a NSLog() call in your useXPressed: to make sure that method is actually getting called when you expect it to?
so, I need to send data backwards when poping two views. I tried using protocol, so this is part of my code:
RootViewController.h
#import <UIKit/UIKit.h>
#import "ThirdViewController.h"
#class SecondViewController;
#interface RootViewController : UIViewController <PassInt>
#property (strong, nonatomic) SecondViewController *secondViewController;
#property (strong, nonatomic) ThirdViewController *thirdViewController;
#property (nonatomic) int intNumber;
#end
RootViewController.m
#import "RootViewController.h"
#import "SecondViewController.h"
#implementation RootViewController
#synthesize secondViewController = _secondViewController;
#synthesize thirdViewController = _thirdViewController;
#synthesize intNumber = _intNumber;
- (void)setIntNumber:(int)number{
_intNumber = number;
}
#pragma mark - View lifecycle
- (void)viewWillAppear:(BOOL)animated {
if(!_thirdViewController){
_thirdViewController = [[ThirdViewController alloc] initWithNibName:#"ThirdViewController" bundle:[NSBundle mainBundle]];
}
if(!_secondViewController){
_secondViewController = [[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:[NSBundle mainBundle]];
self.secondViewController.thirdViewController = self.thirdViewController;
}
[self.navigationController pushViewController:self.secondViewController animated:YES];
}
#end
SecondViewController.h
#import <UIKit/UIKit.h>
#class ThirdViewController;
#interface SecondViewController : UIViewController
#property (strong, nonatomic) ThirdViewController *thirdViewController;
#end
SecondViewController.m
#import "SecondViewController.h"
#import "ThirdViewController.h"
#implementation SecondViewController
#synthesize thirdViewController = _thirdViewController;
...
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex{
[self.navigationController pushViewController:self.userPreferencesViewController animated:YES];
}
#end
ThirdViewController.h
#import <UIKit/UIKit.h>
#protocol PassInt <NSObject>
#required
- (void) setIntNumber:(int)number;
#end
#interface ThirdViewController : UIViewController{
id <PassInt> delegate;
}
#property (retain) id delegate;
- (IBAction)saveChanges;
#end
ThirdViewController.m
#import "ThirdViewController.h"
#implementation ThirdViewController
- (IBAction)saveChanges{
int someInt = 3;
[[self delegate] setIntNumber:someInt];
UINavigationController *tempNavigationController = self.navigationController;
[tempNavigationController popViewControllerAnimated:NO];
[tempNavigationController popViewControllerAnimated:NO];
}
...
#end
I would appreciate any help!
In the UINavigationController reference check the property call :
#property(nonatomic, copy) NSArray *viewControllers
Discussion
The root view controller is at index 0 in the array, the back view controller is at index n-2, and the top controller is at index n-1, where n is the number of items in the array.
That could give you a handle to the rootViewController.
Would that be a good solution for you?
There is other ways. But from your comment I think that could be a match.
[[self.navigationController viewControllers] objectAtIndex:0].someProerty;
Another method could be to use NSNotifications. Have the RootViewController resgister as an observer for a notification posted by the ThirdViewController. Then in the userInfo dictionary of the notification posted by the ThirdViewController, you pass someInt as an NSNumber.
This provides sufficient abstraction because your ThirdViewController doesn't need to know what kind of object requires the information, it is just posting it so interested observers know about it.
Good Luck
You're never assigning anything to the delegate member of your ThirdViewController in the code you posted. Also, delegates should usually be assign, not retain.