I am getting an error as:
protocol declaration not found
I couldn't find out what's the reason. Now I am using ARC. I doubt that the issue is due to that. Here is the code I am using for protocol declaration
//This is the first page we are declaring the Delegate
.h
#protocol ImageDelegate
#optional
-(void)ImageSelected:(UIImage *)ImageName;
#end
#interface GetAddedMovieList : UIViewController<UITableViewDataSource,UITableViewDelegate>{
id<ImageDelegate> delegate;
}
#property(nonatomic, strong)id<ImageDelegate> delegate;
#end
.m
#synthesize delegate;
//This is page in which i tried to set delegate. Here I am getting the error.
#interface ImageEnlarge : UIViewController<ImageDelegate>{
IBOutlet UIImageView *imgEnlarge;
NSString *stgImageName;
}
I see several (possible) issues in your code.
#property(nonatomic, strong)id<ImageDelegate> delegate;
delegates should be weak. GetAddedMovieList do now own the delegate by any mean and therefore shouldn't have an impact on its life cycle.
#synthesize delegate = delegate;
By default #synth uses either ivar_ or _ivar lately. With the latest LLVM #synth aren't necessary anymore btw, neither ivars.
#synthesize outside an #implementation ?
Have you checked your #imports?
It's probably an import loop. Do you #import the correct file for where you are using the protocol? And are you importing that file in the protocol file? If so then you have an import loop. Use forward declaration in the protocol's header instead and that should solve it. (#class)
You are putting an #interface on a .m file, are you trying to create a private #interface? With an IBOutlet declared there?
After seeing your edit, I am guessing there is only missing an import on the .h of your ImageEnlarge class.
Try like it.
#protocol ImageDelegate<NSObject>
#optional
-(void)ImageSelected:(UIImage *)ImageName;
#end
And also add this property.
#property(nonatomic,assign)id<ImageDelegate> delegate;
I think it will be helpful to you.
Related
I'm having a problem when I try to add a second protocol. The first one is working just fine. So I created a test application to try out using two protocols (because I'm still learning how to use protocols). I do not know why I am having so much trouble understanding protocols. I've even gone through tutorials and still struggle with them.
My first issue when I tried to add the second protocol and use it I received the following error:
Assigning to ‘id’ from incompatible type ‘ *const _strong'
But, let's ignore that for now, because my test application is giving me this error for both protocols in my test app:
Cannot find protocol declaration
So, I will post the code for my test application, because I MUST understand the basics before tackling more difficult issues.
DelegateA Header
#import <Foundation/Foundation.h>
#protocol IDDelegateADelegate <NSObject>
#end
#interface IDDelegateA : NSObject
//other properties here
#property (nonatomic, assign) id<IDDelegateADelegate> delegateA;
#end
DelegateA Implementation
#import "IDDelegateA.h"
#implementation IDDelegateA
#synthesize delegateA;
//other methods and properties go here
#end
DelegateB Header
#import <Foundation/Foundation.h>
#protocol IDDelegeteBDelegate <NSObject>
#end
#interface IDDelegeteB : NSObject
//other properties here
#property (nonatomic, assign) id<IDDelegeteBDelegate> delegateB;
#end
DelegateB Implementation
#import "IDDelegeteB.h"
#implementation IDDelegeteB
#synthesize delegateB;
//other methods and properties go here
#end
The test class Header that uses these delegates
#import <Foundation/Foundation.h>
#import "IDDelegateA.h"
#import "IDDelegeteB.h"
#interface IDTestingDelegates : NSObject <IDDelegateA, IDDelegateB>
#end
Right here I receive the Cannot find protocol declaration error for both delegates. I've been searching on SO as well as going through tutorials and sample code. Best answer on SO was here. But I'm just not getting what I'm doing wrong. Can somebody please point out what I am missing here?
#interface IDTestingDelegates : NSObject <IDDelegateA, IDDelegateB>
should be
#interface IDTestingDelegates : NSObject <IDDelegateADelegate, IDDelegeteBDelegate>
You have to list the protocols in <...>, not interfaces.
#interface declares a class, while the ClassName <X> syntax expects X to be a protocol (in your declaration of IDTestingDelegates).
Not sure exactly what you were trying to achieve here.
I'm getting an "incomplete implementation" error in my .m file, but I cannot figure it out how to fix it. I`ll post .h and .m files if you can give me tips on how to fix that. Thanks.
Apparently, I need to put more details, or I cannot post the question because the post contains mostly code, so this are just some dummy lines.
.h File
#import <UIKit/UIKit.h>
#interface BlogViewController : UIViewController <UIPickerViewDelegate, UINavigationControllerDelegate, UIImagePickerControllerDelegate>
- (IBAction)selectPicturePressed:(id)sender;
- (IBAction)blogPost:(id)sender;
#property (weak, nonatomic) IBOutlet UITextView *commentTextField;
#property (weak, nonatomic) IBOutlet UIImageView *imageView;
#property (nonatomic, strong) NSString *username;
#end
.m File
#import "BlogViewController.h"
#import <Parse/Parse.h>
#import "SWRevealViewController.h"
#import "PhotoViewController.h"
#interface BlogViewController ()
-(void)showErrorView:(NSString *)errorMsg;
#end
#implementation BlogViewController **//Incomplete Implementation**
#synthesize imageView = _imageView;
#synthesize username = _username;
#synthesize commentTextField = _commentTextField;
IBActions are just regular functions with syntactic sugar for connecting them to interface builder therefore you have to implement them in the .m file
.m file:
- (IBAction)selectPicturePressed:(id)sender {
// code here
}
- (IBAction)blogPost:(id)sender {
// and here
}
On the line that's giving you the Incomplete Implementation error, you can get more details about what you're missing.
You don't paste all your .m so it's anyone's guess what you're missing, however, your .h declares 2 methods and 3 protocols that you must implement.
Your .m file must have method bodies for these two methods:
- (IBAction)selectPicturePressed:(id)sender;
- (IBAction)blogPost:(id)sender;
Likely, you already have these in here, particularly if these were generated by Ctrl+Dragging from interface builder.
But you must also include, at a minimum, all the required methods from the protocols you declared.
UIPickerViewDelegate protocol official documentation
UINavigationControllerDelegate protocol official documentation
UIImagePickerControllerDelegate protocol official documentation.
(I'm not completely familiar with these protocols and don't know for sure that they actually have any #required methods.)
Your .m also has a private interface, which declares a method you must implement in the implementation.
-(void)showErrorView:(NSString *)errorMsg;
You declared this method in a private interface, so be sure to implement this method as well.
Regardless of what you're missing, Xcode will absolutely tell you if you just click on the error/warning. Xcode will give you the names of the methods its expecting to find in your implementation but cannot.
-(IBAction)ok
{
//send message to the delegate with the new settings
[self.delegate setHeight:_height Width:_width Mines:_mines];
[self.delegate dismissViewControllerAnimated:YES completion:nil];
}
the first message to the delegate wouldn't work until i imported ViewController.h, but the second one worked without the import.
if i add -(void)setHeight:(int)h Width:(int)w Mines:(int)m; as required in the optionsViewController protocol will that mean that i no longer have to import the root .h file.
i intend to use delegation to send messages in other parts of the program so i want to make sure i am using it correctly and not importing things when i don't need to.
Thank you.
if i add -(void)setHeight:(int)h Width:(int)w Mines:(int)m; as required in the optionsViewController protocol will that mean that i no longer have to import the root .h file.
Yes! You could also add it as #optional and it would work (remember to check if the delegate -respondsToSelector: in that case). The whole idea is that your object regularly knows nothing about the delegate object - except that it conforms to the protocol (ie implements the #required and possibly the #optional methods).
Added for clarification (on my phone, which is a pain in the butt):
//OptionsViewController.h
//this object does NOT have to import
//the calling viewControllers .h file
//which is what I think the OP does
#protocol optionsViewControllerProtocol;
#interface OptionsViewController : UIViewController
#property (nonatomic, assign) id<optionsViewControllerProtocol> delegate; //should be id, could be UIViewController too, if absolutely necessary (better design to make it id)
#end
#protocol optionsViewControllerProtocol <NSObject>
#required
-(void) setHeight: (NSInteger) height;
#end
//viewController.h
#import "optionsViewController.h" //necessary to get the protocols definitions
#interface OptionsViewController: UIViewController <optionsViewControllerProtocol>
//.....
If you define your delegate property to be of class UIViewController*, then the compiler will recognize the dismissViewControllerAnimated:completion: method without you needing to import anything, since that's a standard method for that class.
For a custom method, i.e. setHeight:Width:Mines:, you absolutely need to import the header file, or have it imported somewhere up the import chain.
Example: You have MyProtocol.h, and you want SomeClass to have a delegate property that conforms to that protocol. If you #import "MyProtocol.h" in SomeClass.h, you don't need to re-import it in SomeClass.m.
// SomeClass.h
#import "MyProtocol.h"
#interface SomeClass : NSObject
#property (weak, nonatomic) id<MyProtocol> delegate;
#end
//SomeClass.m
#import "SomeClass.h"
#implementation SomeClass
- (void)someMethod
{
[self.delegate myProtocolMethod];
}
#end
I'm having a hard time understanding why the following textfield is declared twice in some tutorials.
In the .h file:
# include <UIKit/UIKit.h>
#interface MyViewController : UIViewController {
UITextField *name; // <----- What do I need this for? Is it the same as below?
}
#property (nonatomic, strong) IBOutlet UITextField *name; // <----- Same as this?
#end
At first I thought this would be something like an instance variable, but they are only declared here in the .m file, right?
.m file
#import "MyViewController.h"
#implementation UIViewController {
NSString *myString; // <----- This is an instance variable, right?
}
What's the "UITextField *name;" for? Don't I only need the second one with the #property in front? Thank you.
This is an old way, just use property is OK.
If you declare both, you must use #synthesize name; in your .m file to make self.name same as name.
XCode4.2 auto synthesize name = _name. So use self.name as much as possible in your .m file.
Variable in {} just use for internal or private, when you don't want implement setter and getter.
If you are targeting iPhone OS or 64-bit Mac OS X then you do not need to define ivars for your properties. Take a look at Dynamic ivars: solving a fragile base class problem
i have two views with view1 calling view2. i need to pass data from view2 back to view1. so i am attempting to set up a delegate. here's what i got in view controller 2:
.h file
#protocol addEventDelegate <NSObject>
-(void) setAddedEventFlag:(BOOL) hasAddedEvent;
#end
#interface AddEventViewController : UIViewController <UITextFieldDelegate, UITextViewDelegate, UIPickerViewDelegate, UIPickerViewDelegate>
#property (weak, nonatomic) id delegate; //changed from strong to weak
i then #synthesize delegate in the .m file
when try to include the addEventDelegate for the first view controller, xcode can not find it:
.h file
#import "AddEventViewController.h"
#interface FieldReportViewController : UIViewController <UITextFieldDelegate,
UITextViewDelegate, UIPickerViewDelegate, UIPickerViewDelegate, addEventDelegate>
i get the error: "Cannot find protocol declaration for 'addEventDelegate'".
what is wrong?
EDIT:
//code
ERRORS:
Make sure your spelling is correct.
Make sure that AddEventViewController.h/.m are added to the project.
Other than that, what you have is fine.
Edit
Something else I would suggest is to rename your delegate, perhaps there is a naming conflict. Although I haven't seen any issues with 'add' and 'set', but I've seen issues in the past when prefixing with, say, 'new'.
Also, clean your project, and rebuild and see if that helps.
There could be a situation if you have multiple targets in your project, and possibly only added AddEventViewController.h/m to one of them, and you are building/debugging a different target.
Here's the correct way to define a protocol
#protocol addEventDelegate; // forward declaration for delegate property
#interface AddEventViewController : UIViewController <UITextFieldDelegate, UITextViewDelegate, UIPickerViewDelegate, UIPickerViewDelegate>
{
id <addEventDelegate> *delegate
}
#property (weak, nonatomic) id <addEventDelegate> *delegate;
#end // interface
#protocol addEventDelegate <NSObject>
// #optional // if you want to make it optional
-(void) setAddedEventFlag:(BOOL) hasAddedEvent;
#end // protocol
Solved the issue. i had an #import loop. I was #importing all my classes in my .h files. i changed to #Class in .h file and moved the #import's to the .m files and works like a charm now.
You can import addEventDelegate in FieldReportViewController.m file
#interface FieldReportViewController ()<AddEventDelegate>
#end
This one is working in my app