I can't get why I can't set delegate. I'm using UINavigationController to switch between two views. Here is my code
SecondViewProtocol.h
#import <Foundation/Foundation.h>
#protocol SecondViewProtocol <NSObject>
#required
-(void)textFieldDidChange:(NSString *)data;
#end
SecondView.h
#import <UIKit/UIKit.h>
#import "SecondViewProtocol.h"
#interface SecondView : UIViewController
#property (nonatomic, retain) id<SecondViewProtocol>delegate;
#end
SecondView.m
#synthesize delegate = _delegate;
.......
-(IBAction)textFieldReturn:(id)sender
{
[[self delegate] textFieldDidChange:[self.textField text]];
}
.......
I have imported SecondViewProtocol.h in FirstView.h
FirstView.m
....
SecondView *secondView = [[SecondView alloc]init];
secondView.delegate = self;
....
Here I get Assigning to id from incompatible type FirtView.
What is wrong here ?
First of all, delegate property should be declared as assign, not retain. You should never retain delegates.
Second, FirstView should conform to SecondViewProtocol like the following.
#interface FirstView: UIViewController <SecondViewProtocol>
Related
I am just learning and trying to put forth some of the knowledge with objective c and cocoa. I have a little program that has a login screen which then displays a main menu. On the main menu view, there is a button that should load a view to be able to add some data to the app. When I click on the button, it doesn't fire the IBAction but throws an error
EXC_BAD_ACCESS [StartMenuViewController performSelector:withObject:]: message sent to deallocated instance 0x6080195e9f90
I know that it is because there is an object that is not instantiated when the message is being sent, but I cannot find out why. Sorry for the code and the novice level here is the main menu view controller StartMenuViewController.m file:
#import "StartMenuViewController.h"
#import "AppDelegate.h"
#import "MasterViewController.h"
#interface StartMenuViewController ()
#end
#implementation StartMenuViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do view setup here.
}
-(IBAction)showStrainView:(id)sender{
AppDelegate *delegate = nil;
delegate = (AppDelegate *)[[NSApplication sharedApplication] delegate];
MasterViewController *addStrainView = [[MasterViewController alloc] initWithNibName:#"MasterViewController" bundle:nil];
[delegate swapView:self.view toView:addStrainView.view];
}
#end
here is the StartMenuViewController.h
#import <Cocoa/Cocoa.h>
#interface StartMenuViewController : NSViewController
#property (weak) IBOutlet NSButton *showStrainViewButton;
#end
Here is the AppDelegate.h
#import <Cocoa/Cocoa.h>
#class loginView, MasterViewController,StartMenuViewController;
#interface AppDelegate : NSObject <NSApplicationDelegate>{
loginView *loginView;
MasterViewController *masterViewController;
}
#property (assign) IBOutlet NSWindow *window;
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
#property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
#property (strong) loginView *loginView;
#property (strong) MasterViewController *masterViewController;
#property (strong) StartMenuViewController *starMenuViewController;
-(void)swapView:(NSView *)view1 toView:(NSView *)view2;
#end
Here is the AppDelegate.m
#import "AppDelegate.h"
#include "MasterViewController.h"
#import "ScaryBugDoc.h"
#import "Strains.h"
#import "loginView.h"
#interface AppDelegate()
#end
#implementation AppDelegate
#synthesize managedObjectContext = _managedObjectContext;
#synthesize managedObjectModel = _managedObjectModel;
#synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
#synthesize loginView;
#synthesize masterViewController;
#synthesize starMenuViewController;
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
// 1. Create the master View Controller
self.loginView = [[loginView alloc] initWithNibName:#"loginView" bundle:nil];
// 2. Add the view controller to the Window's content view
[self.window.contentView addSubview:self.loginView.view];
self.loginView.view.frame = ((NSView*)self.window.contentView).bounds;
}
-(void)swapView:(NSView *)view1 toView:(NSView *)view2{
//[view1 removeFromSuperview];
[self.window.contentView addSubview:view2];
view2.frame = ((NSView*)self.window.contentView).bounds;
}
#end
If you need the loginView.h and loginView.m files I can add them as well. I would appreciate any and all help. Thanks in advance
The problem is here:
MasterViewController *addStrainView = [[MasterViewController alloc]initWithNibName:#"MasterViewController" bundle:nil];
[delegate swapView:self.view toView:addStrainView.view];
You don't keep a reference to the MasterViewController so it gets deallocated even though its view is kept around. Now anytime the view tries to access methods from the view controller, things fail.
You should make addStrainView a child view controller of self in the above code so the view controller sticks around as long as its view.
I have a little trouble with my delegate example. I created a very simple code to learn how delegates work. I know that my delegate not will be called but i can't figure out why?
So here is the complete code. Please tell me what i do wrong. It is really important for me to understand the error in this code.
First Viewcontroller: h.file
#import <UIKit/UIKit.h>
#protocol ViewControllerDelegate;
#interface ViewController : UIViewController
#property (nonatomic, retain) id<ViewControllerDelegate> delegate;
#end
#protocol ViewControllerDelegate <NSObject>
- (void)transfer:(ViewController *)data number:(NSUInteger)value;
#end
First Viewcontroller: m.file
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
#synthesize delegate;
- (void)viewDidLoad
{
[super viewDidLoad];
if ([delegate respondsToSelector:#selector(transfer:number:)]){
[delegate transfer:self number:65];
NSLog(#"delegate called");
}
[delegate transfer:self number:65]; //Try to call without if-statement.
}
#end
SecondViewcontroller: h.file
#import <UIKit/UIKit.h>
#import "ViewController.h"
#interface SecondViewController : UIViewController <ViewControllerDelegate>
#end
SecondViewcontroller: m.file
#import "SecondViewController.h"
#interface SecondViewController ()
#end
#implementation SecondViewController
- (void)transfer:(ViewController *)data number:(NSUInteger)value
{
NSLog(#"received information from ViewController");
}
- (void)viewDidLoad
{
[super viewDidLoad];
ViewController *viewcontroller = [[ViewController alloc] init];
viewcontroller.delegate = self;
}
#end
In the storyboard i use two container views so both ViewControllers will shown.
Your current code is fine. The problem appears to be that you are never loading the view controllers view(s) so the viewDidLoad method isn't being called.
To test, push the viewcontroller, or just request viewcontroller.view.
I have read around, and it seems as though delegates would be really useful in my app. Unfortunately, every tutorial about protocols I have tried has failed - the delegate is not receiving the message! It would be great if someone could tell me what I'm doing wrong.
I created a really simple test app with two ViewControllers, a FirstViewController and a SecondViewController. I have set them up in container views to see the effect properly.
My Main.storyboard looks like this:
The purpose of the test app is to change the background colour of the SecondViewController when one of the buttons is pressed in the FirstViewController.
Here is FirstViewController.h:
#import <UIKit/UIKit.h>
#protocol FirstViewControllerDelegate
-(void)colourDidChange:(UIColor *)theColour;
#end
#interface FirstViewController : UIViewController{
UIButton *redButton;
UIButton *blueButton;
}
#property (nonatomic, retain) id <FirstViewControllerDelegate> delegate;
#property (nonatomic, retain) IBOutlet UIButton *redButton;
#property (nonatomic, retain) IBOutlet UIButton *blueButton;
-(IBAction)redPressed;
-(IBAction)bluePressed;
My FirstViewController.m:
#import "FirstViewController.h"
#interface FirstViewController ()
#end
#implementation FirstViewController
#synthesize redButton, blueButton;
#synthesize delegate;
-(IBAction)redPressed{
[self.delegate colourDidChange:[UIColor redColor]];
}
-(IBAction)bluePressed{
[self.delegate colourDidChange:[UIColor blueColor]];
}
-(void)viewDidLoad
{
[super viewDidLoad];
}
I think I have implemented the protocol and the calling of the delegate correctly.
Here is my SecondViewController.h:
#import <UIKit/UIKit.h>
#import "FirstViewController.h"
#interface SecondViewController : UIViewController <FirstViewControllerDelegate>
-(void)colourDidChange:(UIColor *)theColour;
And my SecondViewController.m:
-(void)colourDidChange:(UIColor *)theColour{
self.view.backgroundColor = theColour;
}
-(void)viewDidLoad
{
[super viewDidLoad];
FirstViewController *firstView = [[FirstViewController alloc]init];
firstView.delegate = self;
}
I have breakpointed the project and realised that colourDidChange: in the SecondViewController is never executed.
It would be much appreciated if someone could point out what I have done wrong, whether declaring (or conforming to) the delegate poorly or not setting the delegate the right way.
Many thanks.
I suspect that there are 2 instances of FirstViewController, one created by your storyboard and another one created in SecondViewController's viewDidLoad method.
When theFirstViewController creates SecondViewController it could set the delegate property or use an Outlet to connect them.
Note: delegate properties should not be retain, they should be assign (or weak with ARC).
You are honestly very close. Container views will call the prepareForSegue: method, so you should be initializing the second view controller's delegate in this method:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"TypeContainerViewSegueNameHere"]) {
SecondViewController *viewController = (SecondViewController *)segue.destinationViewController;
viewController.delegate = self;
}
}
This way you know that you are getting the instance of SecondViewController that will be in use. Also, you do not need to redeclare the delegate method in your SecondViewController.h file:
-(void)colourDidChange:(UIColor *)theColour;
Finally, in storyboard set the title of the container view segue to SecondViewController to whatever title you like and then copy paste that title to where 'TypeContainerViewSegueNameHere' is written above.
EDIT 1:
A typical situation would be similar to this:
#protocol ViewControllerDelegate;
#interface ViewController : UIViewController
#property (nonatomic, strong) id<ViewControllerDelegate>delegate;
#end
#protocol ViewControllerDelegate <NSObject>
- (void) delegateMethod;
#end
...
#implementation ViewController
- (void) buttonAction:(id)sender {
[self.delegate delegateMethod];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"TypeContainerViewSegueNameHere"]) {
SecondViewController *viewController = (SecondViewController *)segue.destinationViewController;
viewController.delegate = self;
}
}
#end
...
#interface SecondViewController : UIViewController <ViewControllerDelegate>
#end
...
#implementation SecondViewController
- (void)delegateMethod {
}
#end
That said, you could make your main view controller the delegate of your FirstViewController, which has the two view containers as seen in your screenschot. And then call a delegate method from the main view controller to the second view controller. Although I am curious as to why you have these two view controllers as child view controllers rather than placing a view and two buttons in one view controller.
EDIT 2:
Here is an example (written quickly and not tested). Think of it as a triangle of delegates:
#protocol FirstViewControllerDelegate;
#interface FirstViewController : UIViewController
#property (nonatomic, strong) id<FirstViewControllerDelegate>delegate;
#end
#protocol FirstViewControllerDelegate <NSObject>
- (void) firstViewControllerDelegateMethod;
#end
...
#implementation FirstViewController
- (void) buttonAction:(id)sender {
[self.delegate firstViewControllerDelegateMethod];
}
#end
...
#protocol MainViewControllerDelegate;
#interface MainViewController : UIViewController <FirstViewControllerDelegate>
#end
#protocol MainViewControllerDelegate <NSObject>
- (void) mainViewControllerDelegateMethod;
#end
...
#implementation MainViewController
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"TypeContainerViewSegueNameHere"]) {
SecondViewController *viewController = (SecondViewController *)segue.destinationViewController;
viewController.delegate = self.delegate;
}
if ([segue.identifier isEqualToString:#"TypeContainerViewSegueNameHere"]) {
FirstViewController *viewController = (FirstViewController *)segue.destinationViewController;
viewController.delegate = self;
}
}
- (void)firstViewControllerDelegateMethod {
[self.delegate mainViewControllerDelegateMethod];
}
#end
...
#interface SecondViewController : UIViewController <MainViewControllerDelegate>
#end
...
#implementation SecondViewController
- (void)mainViewControllerDelegateMethod {
}
#end
Like I said, you should think about reducing the complexity of this section of your app and consider putting all of your views in one view controller.
I am trying to improve myself in Objective-C and what I am on about is now modifying and changing and existed project. I did everything I wanted expect one thing. Theres an info button in my program and it doesnt related with .xib file. I tried to remove it but always my main.m gave error like SIGABRT (int retval thing.)
Here is the thing what I want to modify
http://i.stack.imgur.com/ZG51s.png // The picture of my program and info button
I am trying to remove the (i) button on the right-down corner.
Here's my code
This is my RootViewController.h
#import <UIKit/UIKit.h>
#class MainViewController;
#interface RootViewController : UIViewController {
IBOutlet UIButton *infoButton; //Silinecek
MainViewController *mainViewController;
}
#property (nonatomic, retain) MainViewController *mainViewController;
#end
This is my RootViewController.m
#import "RootViewController.h"
#import "MainViewController.h"
#implementation RootViewController
#synthesize mainViewController;
- (void)viewDidLoad {
MainViewController *viewController = [[MainViewController alloc] initWithNibName:#"MainView" bundle:nil];
self.mainViewController = viewController;
[viewController release];
[self.view insertSubview:mainViewController.view belowSubview:infoButton];
}
and also I tried to modify my AppDelegate h and m. Here they are ;
#import <UIKit/UIKit.h>
#class RootViewController;
#interface AppDelegate : NSObject <UIApplicationDelegate> {
IBOutlet UIWindow *window;
IBOutlet RootViewController *rootViewController;
}
#property (nonatomic, retain) UIWindow *window;
#property (nonatomic, retain) RootViewController *rootViewController;
#end
#import "AppDelegate.h"
#import "RootViewController.h"
#implementation AppDelegate
#synthesize window;
#synthesize rootViewController;
- (void)applicationDidFinishLaunching:(UIApplication *)application {
[window addSubview:[rootViewController view]];
//[window makeKeyAndVisible];
}
/*
- (void)dealloc {
[rootViewController release];
[window release];
[super dealloc];
}
*/
What should I do for removing that info button in my View. Thanks for the any tips
And if you are interested in this is the whole algorithm : http://pastebin.com/hHQkQYS6
Do you still have the control linked somewhere in your xib file? It is declared as an IBOutlet control. Usually when I have these controls I will use the GUI link this control in some way (I can't remember what exactly as I have not done Obj-C in a long time). But I would definitely have a look around you xib file (as well as removing [self.view insertSubview:mainViewController.view belowSubview:infoButton];
The exception mentions:
[<RootViewController 0x4b9ab20> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key infoButton.
The call stack shows that it is thrown by UINib. So this is happening during nib load. So check for all objects present, carefully, in the nib and remove the info button
I'm getting the error mentioned in the title.
Here's my interface:
#import <UIKit/UIKit.h>
#class ControllerLevel1;
#interface RootController : UIViewController {
ControllerLevel1 *controllerLevel1;
}
#property (retain, nonatomic) ControllerLevel1 *controllerLevel1;
#end
And here's the implementation:
#import "RootController.h"
#import "ControllerLevel1.h"
#implementation RootController
#synthesize controllerLevel1;
- (void)viewDidLoad {
ControllerLevel1 *firstLevel = [[ControllerLevel1 alloc]initWithNibName:#"ControllerLevel1" bundle:nil];
self.controllerLevel1 = firstLevel;
[self.view insertSubview:firstLevel.view atIndex:0];
[firstLevel release];
[super viewDidLoad];
}
The error occurs in [self.view insertSubview:firstLevel.view atIndex:0];
It's complaining about firstLevel.view.
So, likely you didn't declare "view" as a property in ControllerLevel1.h. Show us the .h file for that and we can help more.