#interface RecentPhotosViewController () <PhotoViewControllerDelegate>
- (void)viewDidLoad
{
[super viewDidLoad];
[[self.tabBarController.viewControllers objectAtIndex:1] setDelegate:self];
}
The RecentPhotosViewController is a tableviewcontroller which implements a delegate.
I want to set self(RecentPhotosViewController) as the delegate in vieDidLoad(), but when i tried to type:self.setDelegate it turned out self doesn't have this setDelegate method, then i tried this:[[self.tabBarController.viewControllers objectAtIndex:1] setDelegate:self];(this tableview is one of the viewcontrollers of the tabBarControllers.
Then i got an error:[RecentPhotosViewController setDelegate:]: unrecognized selector sent to instance 0xc939960. I don't know how to fix this.
Do this:
#interface RecentPhotosViewController
//etc.
#property (nonatomic, assign) id delegate;
#end
#implementation RecentPhotosViewController
// etc.
#synthesize delegate;
#end
Related
I have a UIViewController on a UINavigationStack and from this UIView I load another view not onto the stack but as a subview. This view that I load is just a preferences view for the app that I overlay onto what ever is showing.
i.e.
myViewController <- on the stack button touch loads as a subview to myViewController
+ prefrencesViewController
My question is, is there a way to call a method thats in myViewController from prefrencesViewController? I am trying to use delegates and protocols but its not working, so I am hoping there is either an easy way to do this I don't know about yet or maybe I could get some help with my delegate/protocol...
This is what my code looks like for delegate and protocol set up
//prefrencesViewController.h
#protocol GetPrefrencesViewControllerDelegate <NSObject>
-(void)reloadViewFromSavedPrefrences;
#end
//delegates and protocols
#property (nonatomic, weak) id <GetPrefrencesViewControllerDelegate> delegate;
//prefrencesViewController.m
//delegates and protocols
#synthesize delegate;
//.. inside button action
[[self delegate] reloadViewFromSavedPrefrences];
//myViewController.h
#import "prefrencesViewController.h"
#interface myViewController : UIViewController <UITabBarDelegate, GetGUIEncodedData, GetPrefrencesViewControllerDelegate> {
// prefrencesViewController set up
prefrencesViewController *pvc;
#property (strong, nonatomic) prefrencesViewController *pvc;
//myViewontroller.h
#synthesize pvc;
- (void)viewDidLoad
{
//..
[pvc setDelegate:self];
}
//Delegate and prefrences.. Saved pressed reload the view here.
-(void)reloadViewFromSavedPrefrences {
NSLog(#"WORKED");
}
any help would be greatly appreciated
I'm not sure that you are following the steps that I will present below but if you don't here is the example.
PresentedViewController.h
//import stuff
#protocol PresentedViewControllerDelegate <NSObject>
-(void)methodThatSouldBeImplementedByOtherController; //you can add params
#end
#interface PresentedViewController : UIViewController {
//instance variables
}
#property (nonatomic, assign(week for ARK)) id<PresentedViewControllerDelegate>delegate
//public methods here
PresentedViewController.m
#implementation PresentedViewController
#synthesize delegate;
//method implementation here
-(IBAction)buttonThatWillCallTheDelegate:(id)sender {
if([self.delegate respondsToSelector:#selector(methodThatSouldBeImplementedByOtherController)]) {
[self.delegate methodThatSouldBeImplementedByOtherController];
}
}
ControllerThatWillPresent.h
#interface ControllerThatWillPresent : UIViewController <PresentedViewControllerDelegate> {
//instance variables
}
//some methods maybe
ControllerThatWillPresen.m
#implementation ControllerThatWillPresen
-(void)methodThatWillShowTheVC {
PresentedViewController *vc = [PresentedViewController alloc] init]; //initWithNibname...
vc.delegate = self;
//presentVc, pushVc, addChild ...
}
-(void)methodThatSouldBeImplementedByOtherController {
//do stuff in delegate method
}
I'm working through the IOS HelloWorld example and I have a question regarding setting the delegate for a TextField. In the example it was as easy as control-dragging from the TextField to the ViewController. But now say I wanted to create a custom class to act as my delegate as so:
#import <Foundation/Foundation.h>
#interface SweetAssDelegate : NSObject <UITextFieldDelegate>
- (BOOL)textFieldShouldReturn:(UITextField *)theTextField;
#end
#import "SweetAssDelegate.h"
#implementation SweetAssDelegate
- (BOOL)textFieldShouldReturn:(UITextField *)theTextField
{
NSLog(#"Calling Delegate");
[theTextField resignFirstResponder];
return YES;
}
#end
How can I set this class to be the delegate of the TextField? As far as I can tell there is not way to accomplish this through the GUI. I tried manually setting the delegation after window load with no success:
#import "ViewController.h"
#import "SweetAssDelegate.h"
#interface ViewController ()
#property (weak, nonatomic) IBOutlet UITextField *inputField;
#end
- (void)viewDidLoad
{
[super viewDidLoad];
SweetAssDelegate *foo = [[SweetAssDelegate alloc] init];
[self.inputField setDelegate:foo];
NSLog(#"Delegate: %#", self.inputField.delegate);
}
I actually receive some sort of memory exception when bringing up the keyboard? Any ideas? Thanks.
As a side question, where should I always use viewDidLoad to initialize any variables? I noticed that init was not being called???
Your delegate object, foo, is allowed to fall out of scope and is released at the end of viewDidLoad and by the time the keyboard comes up, it doesn't exist anymore. Make it an ivar (or property) of your view controller, or otherwise make sure that foo doesn't fall out of scope at the end of viewDidLoad.
Thus, it could be something like:
#interface ViewController ()
#property (weak, nonatomic) IBOutlet UITextField *inputField;
#property (strong, nonatomic) SweetAssDelegate *foo;
#end
- (void)viewDidLoad
{
[super viewDidLoad];
self.foo = [[SweetAssDelegate alloc] init];
[self.inputField setDelegate:self.foo];
NSLog(#"Delegate: %#", self.inputField.delegate);
}
Your textfield delegate must have the implemented to be your textfield delegate I guess.
A delegate manages the communication between objects, which means your custom delegate must allow communication between objects and must provide methods, the textfield can work with...
Another example is a tableView:
You can make a custom delegate which implements the delegates and then calls some tableview related Methods...
Here this code might be interesting for you:
#interface myCustomDelegateForTextFields <UITextFieldDelegate>
#end
#implementation myCustomDelegateForTextFields
- (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
return TRUE;
}
#end
#implementation ViewController
myCustomDelegateForTextFields *txtfielddelegate = [[myCustomDelegateForTextFields alloc] init];
UITextField *whatever;
whatever.delegate = txtfielddelegate;
//your textfield now listens to the BOOL method in your custom delegate
#end
Is it that what u were looking for? :)
you can ofc pack the myCustomDelegateForTextField delegate in another class and call the class
I am building a utility application which shares data between main view and flip view. Actually, it is not exactly the flip view that's holding data, it's the custom view that's an instance of the flip view when it gets loaded. I have explained the specifics in my previous thread here, but I haven't got a solution yet. And I have redeveloped my code, hopefully this time I could make myself clear.
The general concept here is I create and store data in my main view, and pass it to the flip side view using the predefined delegate in the FlipViewController. Then in the FlipViewController, I store the data in my own delegate and pass it to the custom view which implements my own delegate method. The following is the main portions of the code.
MainViewController.m (only adopts <FlipsideViewControllerDelegate> protocol)
- (IBAction)showInfo:(id)sender {
FlipsideViewController *controller = [[FlipsideViewController alloc] initWithNibName:#"FlipsideView" bundle:nil];
controller.delegate = self;
controller.chart = data;
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:controller animated:YES];
[controller release];
}
FlipsideViewController.h
#protocol FlipsideViewControllerDelegate;
#protocol ChartDelegate;
#interface FlipsideViewController : UIViewController {
id <FlipsideViewControllerDelegate> delegate;
id <ChartDelegate> delegate2;
DataModel *chart;
}
#property (nonatomic, assign) id <FlipsideViewControllerDelegate> delegate;
#property (nonatomic, assign) id <ChartDelegate> delegate2;
#property (nonatomic, retain) DataModel *chart;
- (IBAction)done:(id)sender;
#end
#protocol FlipsideViewControllerDelegate
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller;
#end
#protocol ChartDelegate <NSObject>
- (void)getParams:(DataModel *)dataModel;
#end
FlipsideViewController.m
#synthesize delegate, delegate2;
#synthesize chart;
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor viewFlipsideBackgroundColor];
if ([delegate2 respondsToSelector:#selector(getParams:)]) {
[delegate2 getParams:chart];
}
}
customDrawing.h
#interface customDrawing : UIView <ChartDelegate>{
DataModel *chartData;
}
#property (nonatomic, retain) DataModel *chartData;
#end
customDrawing.m
#synthesize chartData;
-(void)getParams:(DataModel *)dataModel{
chartData = dataModel;
}
It turns out the data didn't get passed to the chartData object in my custom view. HELP?
You are missing the fundamentals. I do not think you need delegates to achieve this task but here we go.
A protocol is like a contract. In you FlipsideViewController class you defined the protocol which essentially states if you conform to this protocol then you must implement this method.
How do you conform to a protocol?
In MainViewController the #interface will look something like this
#interface MainViewController : UIViewController <FlipsideViewControllerDelegate>
The fact that you have the protocol written in angled brackets means that you promise to conform to the protocol and therefore have to implement
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller;
in your MainViewController.m.
Now when MainNavigationController set's itself as the delegate (controller.delegate = self;) it finishes the link. This allows the FlipsideViewController to call
[delegate flipsideViewControllerDidFinish:self];
Which will call the method defined in MainViewController which dismisses the modal view controller.
You have defined a second protocol (you could have added the method to the first and then you would not have to adopt two protocols) and as others have pointed out you have not linked the classes up by doing
controller.delegate2 = self;
This would not solve your problem. You would still need to conform to the ChartDelegate by adding it to the declaration. Once you have done that you will still not be out of the water because the method is not correct.
Full solution - not using delegates as they are not really required here
MainViewController.h
#interface MainViewController : UIViewController <FlipsideViewControllerDelegate>
- (IBAction)showInfo:(id)sender;
#end
MainViewController.m
#implementation MainViewController
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller
{
[self dismissModalViewControllerAnimated:YES];
}
- (IBAction)showInfo:(id)sender
{
FlipsideViewController *controller = [[FlipsideViewController alloc] initWithNibName:#"FlipsideView" bundle:nil];
controller.delegate = self;
/*
* The labelText property is defined in the header for FlipsideViewController
* In this case this is the easiest way to get data from this controller to
* the controller we are about to display
*/
controller.labelText = #"WHAT EVER YOU WANT TO SEND"; // <---- sending data
controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:controller animated:YES];
[controller release];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#end
FlipsideViewController.h
#class FlipsideViewController;
#protocol FlipsideViewControllerDelegate
- (void)flipsideViewControllerDidFinish:(FlipsideViewController *)controller;
#end
#interface FlipsideViewController : UIViewController
/*
* These properties have been added. The label is used for displaying the text
* and needs to be hooked up in Interface builder
*
* The NSString is the property that is holding the data passed from MainViewController
*/
#property (nonatomic, retain) IBOutlet UILabel *testLabel;
#property (nonatomic, copy) NSString *labelText; from MainViewControlller
#property (nonatomic, assign) id <FlipsideViewControllerDelegate> delegate;
- (IBAction)done:(id)sender;
#end
FlipsideViewController.m
#implementation FlipsideViewController
#synthesize delegate = _delegate;
/*
* We need to synthesise out properties so we get our getters and setters created
*/
#synthesize testLabel = _testLabel;
#synthesize labelText = _labelText;
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
/*
* This is called once the view is set up and all connections have been made in
* interface builder. Therefore we can now set the text of our test label
*/
self.testLabel.text = labelText;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#pragma mark - Actions
- (IBAction)done:(id)sender
{
[self.delegate flipsideViewControllerDidFinish:self];
}
- (void)dealloc
{
/*
* Memory management for the ivars we added
*/
[_testLabel release];
[_labelText release];
[super dealloc];
}
#end
You have two properties: delegate and delegate2. You are assigning a value to delegate, but calling the method on delegate2 later.
You need to assign the delegate2 (your customDrawing class). You are only assigning the delegate.
I'm new to Objective C and I'm having trouble getting delegates to work in my code.
I have a class called cViewController and in this class has a UIWebView to fetch webpages and a button above it that calls a popover class called prodMenu. What I'm having trouble with is that the function to call webpages from the prodMenu class and display it on the parent UIWebView isn't working.
cViewController.h
#import <UIKit/UIKit.h>
#import "prodMenu.h"
#interface cViewController : UIViewController <prodMenuDelegate>{
UIPopoverController *cpopover;
IBOutlet UIWebView *webImageDisplay;
}
#property (nonatomic, retain) UIWebView *webImageDisplay;
#property (nonatomic, retain) UIPopoverController *cpopover;
- (IBAction)cPopoverTapped:(id)sender;
- (void) fetchWebsite:(NSString *)website; //This is the delegate method I'm trying to call in the popover class.
#end
cViewController.m
- (IBAction)cPopoverTapped:(id)sender {
prodMenu *tp = [[prodMenu alloc] init];
cpopover = [[UIPopoverController alloc] initWithContentViewController:tp];
[tp release];
CGRect rect = CGRectMake(40, 0, 50, 50);
cpopover.popoverContentSize = CGSizeMake(250, 225);
[cpopover presentPopoverFromRect:rect inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:YES];
}
- (void)fetchWebsite:(NSString*)website{ //This function is called by prodMenu class
NSLog(#"address: %#", website);
NSString *urlAddress = website;
NSURL *url = [NSURL URLWithString:urlAddress];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[webImageDisplay loadRequest:requestObj];
[webImageDisplay release];
}
- (void)viewDidLoad {
[self fetchWebsite:#"http://www.yahoo.com"];
[super viewDidLoad];
}
prodMenu.h
#import <UIKit/UIKit.h>
#protocol prodMenuDelegate;
#interface prodMenu : UIViewController{
<prodMenuDelegate> delegate;
}
- (IBAction)radBtn:(id)sender; //This is the IBAction that calls the fetchWebsite function
#property (nonatomic, assign) id <prodMenuDelegate> delegate;
#end
#protocol prodMenuDelegate
- (void)fetchWebsite:(NSString *)website;
#end
prodMenu.m
#import "prodMenu.h"
#import "cViewController.h"
#implementation prodMenu
#synthesize delegate;
- (IBAction)radBtn:(id)sender{
[delegate fetchWebsite:#"http://www.google.com"]; //Here is the call to the method
}
Am I missing something here to call the delegate method? There aren't any errors or warnings. All I want to do is when the user presses a button on the popover view, the parent class underneath changes the webpage. Thanks in advance.
Just a quick idea. Have you tried declaring the delegate protocol like this
#protocol prodMenuDelegate <NSObject>
...
#end
? I often ran into troubles when omitting the < NSObject >. Also I think there is an 'id' missing in
#interface prodMenu : UIViewController{
<prodMenuDelegate> delegate;
}
Edit: Also, in the code you posted I do not see where you actually assign the prodMenu's delegate.
I have this problem....
in my viewcontroller.h I defined my class like this:
myClass* iR;
and after:
#property (nonatomic,retain) IBOutlet myClass* iR;
into myClass.h I added this:
#protocol myClassDelegate <NSObject>
-(void) didLogon:(bool)isLogged;
#end
and after:
#property (nonatomic, assign) id<myClassDelegate> delegate;
now, into my class, in the connectionDidFinishLoading method ( I used a nsurlconnection to retrieve the login data I added this:
[self.delegate didLogon:true];
into myviewcontroller.h:
<myClassDelegate>
and into myviewcontroller.m:
-(void)didLogon:(bool)isLogged{
...
}
but the program go inside the self.delegate didLogon but into myviewcontroller.m didn't go... did you understand why???
Where are you assigning the delegate? You need something like this:
MyViewController *viewController = [[MyViewController alloc] init];
self.delegate = viewController;
Just to be safe, when you call delegate methods, call them like this:
if ([self.delegate respondsToSelector:#selector(didLogon:)]) {
[self.delegate didLogon:YES];
}
That way, if the delegate doesn't support that method, your program won't crash when it doesn't recognize that selector.