my protocol method isn't called ... i'm new in obj-c programming ...
i have a header file for protocol
..........CanUpdateTime.h .....................
#import <Foundation/Foundation.h>
#protocol CanUpdateTime
-(BOOL)canUpdateTime;
#end
..............class interface where i declare my delegate variable and set it's property ..............
#import <UIKit/UIKit.h>
#import "Currency.h"
#import "CanUpdateTime.h"
#protocol CanUpdateTime;
#interface CurrencyViewController : UIViewController <UITableViewDelegate, UITableViewDataSource > {
Currency *currency;
UILabel *dayMonthYear;
id <CanUpdateTime> update;
}
#property (nonatomic, retain) Currency *currency;
#property (nonatomic, retain) IBOutlet UILabel *dayMonthYear;
#property (nonatomic, assign) id <CanUpdateTime> update;
........ implementation file ..............
-(void)viewDidLoad {
[[self update]canUpdateTime];
}
..... the class where i placed the definition of delegate method ...
#interface ExchangeRatesProvider : NSObject <NSXMLParserDelegate,CanUpdateTime> {
and so on ...
}
.... implementation file ..................
-(BOOL)canUpdateTime {
NSLog (#"ok");
return YES;
}
but nothing happens ... i tried to pass to de update(delegate) respondsToSelector method but
nothing happens ... my delegate method doesnt respond ... any ideas ... ???
p.s. sorry for my english ... thanks for attention ...
In ExchangeRatesProvider you should set the delegate for CurrencyViewController as
currencyController.update = self;
where currencyController is an instance of CurrencyViewController
My best guess is that your update variable has never been filled with an ExchangeRatesProvider instance.
At some point in your code and before calling [[self update] canUpdateTime] you need to put an object that conforms to your protocol in the variable.
Looking at your code I think the missing line here is :
ExchangeRatesProvider* provider = [[ExchangeRatesProvider alloc] init];
[[self setUpdate:provider];
These lines can be at the very beginning of viewDidLoad or in the init method.
Don't forget to release the provider when you're done with it with a [self setUpdate:nil]
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
}
So basically I have a protocol inside my interface that I need to include in my implementation because I am getting an incomplete error and therefore can't continue.
. h file
#interface waveLayer1 : CCLayer <GameKitHelperProtocol>
{
...
}
.m file
#implementation waveLayer1
GameKitHelper.h file
#import "cocos2d.h"
#import <GameKit/GameKit.h>
#protocol GameKitHelperProtocol
-(void) onLocalPlayerAuthenticationChanged;
-(void) onFriendListReceived: (NSArray*)friends;
-(void) onPlayerInfoReceived:(NSArray*)players;
#end
#interface GameKitHelper : NSObject {
id<GameKitHelperProtocol> delegate; bool isGameCenterAvailable; NSError* lastError;
}
#property (nonatomic, retain) id<GameKitHelperProtocol> delegate;
#property (nonatomic, readonly) bool isGameCenterAvailable; #property (nonatomic, readonly) NSError* lastError;
+(GameKitHelper*) sharedGameKitHelper;
// Player authentication, info
-(void) authenticateLocalPlayer;
-(void) getLocalPlayerFriends;
-(void) getPlayerInfo:(NSArray*)players;
#end
The error is "Method in protocol not implemented" I have more files I can show ,but to save room I decided to see if you can help me fix this with just these codes
#interface waveLayer1 : CCLayer <GameKitHelperProtocol>
This says that "wavelayer1" implements the protocol "GameKitHelperProtocol".
Method in protocol not implemented
says that a method declared in a protocol has not been implemented. Chances are that you forgot to implement one of the "GameKitHelperProtocol" methods, which makes your class NOT implement that protocol, which violates the declaration you made, which causes the compiler to output an error.
Implement these 3 methods in your waveLayer1 class..
-(void) onLocalPlayerAuthenticationChanged;
-(void) onFriendListReceived:(NSArray*)friends;
-(void) onPlayerInfoReceived:(NSArray*)players;
When you declare that a class adopts a protocol, you must write an implementation for all required methods that are defined in that protocol. So in this case, you need to add method implementations that are defined in GameKitHelperProtocol.
I have a superclass of UIViewController - MasterViewController which declares a property called itemsViewController. This declares a method called from the MasterViewController, and is wired up via a storyboard in IB.
I have a subclass of MasterViewController which redeclares this property as a specific iPad version, but I can't access the redeclared property from the parent class.
MasterViewController
#interface MasterViewController : UIViewController {
}
#property (nonatomic, strong) IBOutlet ItemsViewController *itemsViewController;
#end
#implementation MasterViewController
#synthesize itemsViewController;
-(void)viewDidLoad {
// I can access itemsViewController in viewDidLoad.
}
#end
MasterViewController_iPad
#interface MasterViewController_iPad : MasterViewController {
IBOutlet ItemsViewController_iPad *_itemsViewController;
}
#property (nonatomic, strong) IBOutlet ItemsViewController_iPad *itemsViewController;
#end
#implementation MasterViewController_iPad
#synthesize itemsViewController = _itemsViewController;
-(void)viewDidLoad {
[super viewDidLoad];
// when I call super viewDidLoad, itemsViewController is nil, as though the property hasn't been overriden
// _itemsViewController is not nil in viewDidLoad.
}
#end
Am I misunderstanding the way property inheritance works in Objective-C?
You can't change the type signature of a method when you override a superclass method.
MasterViewController has these methods:
(void)setItemsViewController:(ItemsViewController *)foo
(ItemsViewController *)itemsViewController
But you're trying to give MasterViewController_iPad these methods:
(void)setItemsViewController:(ItemsViewController_iPad *)foo
(ItemsViewController_iPad *)itemsViewController
Which you can't do: you can't overload the same method name but have different types for the arguments.
If ItemsViewController_iPad is a subclass of ItemsViewController, a quick solution would be to keep the same signature as in MasterViewController but simply use an ItemsViewController_iPad when you set the property.
You can use category if you'd like to override property. Here is example:
I have PDFFileChooserViewController with PDFFileModel and PDFFilesDataSource and some logic related to this properties.
#class PDFFileModel, PDFFilesDataSource;
#interface PDFFileChooserViewController : UIViewController
#property (nonatomic, strong) PDFFileModel* selectedModel;
#property (nonatomic, strong) PDFFilesDataSource*dataSource;
#end
Then I'd like to add specific ViewController for choosing files from Dropbox but my model have some additional fields for example dropboxPath and my DropboxDataSource gets files using another way. So I decided to create category and override this properties:
#import "PDFFileChooserViewController.h"
#class DropboxFileModel,DropboxDataSource;
#interface DropboxViewController : PDFFileChooserViewController
#end
#interface DropboxViewController (ModelCategory)
#property(nonatomic, strong) DropboxFileModel* selectedModel;
#property(nonatomic, strong) DropboxDataSource* dataSource;
#end
Notice that this category will be visible inside DropboxViewController only where I can manipulate with that properties but another classes see only super class interface
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.
I simply want to change a variable of an object from another class. I can compile without a problem, but my variable always is set to 'null'.
I used the following code:
Object.h:
#interface Object : NSObject {
//...
NSString *color;
//...
}
#property(nonatomic, retain) NSString* color;
+ (id)Object;
- (void)setColor:(NSString*)col;
- (NSString*)getColor;
#end
Object.m:
+(id)Object{
return [[[Object alloc] init] autorelease];
}
- (void)setColor:(NSString*)col {
self.color = col;
}
- (NSString*)getColor {
return self.color;
}
MyViewController.h
#import "Object.h"
#interface ClassesTestViewController : UIViewController {
Object *myObject;
UILabel *label1;
}
#property UILabel *label1;
#property (assign) Object *myObject;
#end
MyViewController.m:
#import "Object.h"
#implementation MyViewController
#synthesize myObject;
- (void)viewDidLoad {
[myObject setColor:#"red"];
NSLog(#"Color = %#", [myObject getColor]);
[super viewDidLoad];
}
The NSLog message is always Color = (null)
I tried many different ways to solve this problem, but no success.
Any help would be appreciated.
Thanks for the help so far.
I modified the code as follow, but it still doesn't work as it should.
MyViewController.h:
#import <UIKit/UIKit.h>
#import "Object.h"
#interface MyViewController : UIViewController {
Object *myObject;
}
#property (nonatomic, retain) Object *myObject;
#end
MyViewController.m:
#import "MyViewController.h"
#import "Object.h"
#implementation MyViewController
#synthesize myObject;
- (void)viewDidLoad {
Object *myObject = [Object new];
myObject = 0;
[myObject setColor:#"red"];
NSLog(#"color = %#", myObject.color);
[super viewDidLoad];
}
If I do it like this, NSLog returns color = null (and I think myObject is only visible in viewDidLoad). How can declare myObject and make it visible in MyViewController?
I stripped down my Object class to
Object.h:
#interface Object : NSObject {
NSString *color;
}
#property(nonatomic, retain) NSString *color;
#end
Object.m:
#import "Object.h"
#implementation Object
#synthesize color;
#end
I wasn't able to define an object myObject in ViewDidLoad so that I can access its properties from the whole ViewController class? What did I miss?
Side question: Why do I have to set myObject to 0?
You're declaring a property, then explicitly declaring the accessors in Object.h. You only need to do one or the other - they mean the same thing (well, almost - you'll have color instead of getColor)
To implement the property in Object.m you should use #synthesize color. The explicit implementations, again, are then redundant (unless they do anything extra).
The explicit setColor implementation in Object.m is calling the property - which you are implementing explicitly, so I would have expected you to get an infinite recursion here.
MyViewController.m should probably synthesize label1, since you declare the property in the header (although it's not being used in your snippet).
[myObject getColor] is calling the color property, which you declared but did not synthesize. If you had explicitly implemented it as color it would have picked that up - but it won't match getColor (which is fortunately as that would have led to an infinite recursion again.
I don't see anywhere where you create your myObject instance. If you don't it will be nil and methods called on it (including property accesses) will return 0 or nil.
I suspect (6) is the cause of your issue, but the others need to be addressed too. Make sure you read up on property syntax.