I don't like warnings lying around and this one has been bothering me. Any ideas on what I am doing wrong? I have tons of properties using this same approach and none of them are giving me warnings. Why doesn't Xcode recognize this one?
While the app works as expected, Xcode gives me the following compile time warning:
'OnlinePeerBrowser' may not respond to '-setMyParent:'
My property declaration in OnlinePeerBrowser.h
#import "WelcomeViewController.h"
#interface OnlinePeerBrowser : UIViewController <UITableViewDelegate, UITableViewDataSource, NSNetServiceBrowserDelegate> {
WelcomeViewController *_myParent;
}
#property (nonatomic, assign) WelcomeViewController *myParent;
OnlinePeerBrowser.m has
#synthesize myParent=_myParent;
I am getting the warning on setMyParent in WelcomeViewController.m here...
#import "WelcomeViewController.h"
#import "OnlinePeerBrowser.h"
#implementation WelcomeViewController
- (void)peerPickerController:(GKPeerPickerController *)picker didSelectConnectionType:(GKPeerPickerConnectionType)type {
...
OnlinePeerBrowser *controller = [[OnlinePeerBrowser alloc]
initWithNibName:#"OnlinePeerBrowser" bundle:nil];
[controller setMyParent:self];
}
Also, what is weird is that I can not use the dot syntax here either.
controller.myParent = self;
gives me the following error:
/Users/vesselhead/Development/iPhone/DJBox/WelcomeViewController.m:254: error: request for member 'myParent' in something not a structure or union
I feel like I must be missing something very simple.
The code you've posted looks correct. That means that the compiler is pulling in another declaration of the OnlinePeerBrowser class from somewhere.
Check for circular imports.
Check if you have multiple copies of the OnlinePeerBrowser.h file.
Add the line #warning Testing to your OnlinePeerBrowser.h file. That warning should then appear in the log when you compile. If that warning doesn't appear then that file isn't being picked up by the compiler.
If it's a circular import then don't import "WelcomeViewController.h" in "OnlinePeerBrowser.h". Instead, use a forward declaration in OnlinePeerBrowser.h, e.g. #class WelcomeViewController , and import "WelcomeViewController.h" in OnlinePeerBrowser.m
Sometimes Circular Imports create an issue with the compiler.
Instead of using
#import "WelcomeViewController.h"
in OnlinePeerBrowser.h move that line to the OnlinePeerBrowser.m and add
#class WelcomeViewController
to the OnlinePeerBrowser.h
this will allow you to set the Class of myParent and _myParent to WelcomeViewController and not have the Circular Import.
Alternatively:
you may want to use a #protocol that the WeclomeViewController would have to adhere to. Then you would only have to import the Classes in one direction.
the implementation for a Protocol property would be as Follows
//#import "WelcomeViewController.h"
#protocol OnlinePeerBrowserParent <NSObject>
#required
- (NSString*) informationFromParent;
#end
#interface OnlinePeerBrowser : UIViewController <UITableViewDelegate, UITableViewDataSource, NSNetServiceBrowserDelegate> {
id<OnlinePeerBrowserParent> _myParent;
}
#property (nonatomic, assign) id<OnlinePeerBrowserParent> myParent;
notice the Protocol is on the OnlinePeerBrowser.h so you can import the OnlinePeerBrowser.h and get the Protocol by default.
finally you implement the Protocol in the WelcomeViewController as so
#implementation WelcomeViewController<OnlinePeerBrowserParent>
- (NSString*) informationFromParent
{
return #"My Parental Info";
}
...... etc
Related
I got SO questions also same as this and I tried with solution but still its not working for mine so asked this again.
This is my VCWithProtocol.h
#protocol mydemoDelegate
#optional
-(void)demoDelegateMethodWithSuccess:(BOOL)yesOrNo;
#end
#interface VCWithProtocol : UIViewController
{
id<mydemoDelegate>mydelegate;
}
#property (nonatomic,assign)id<mydemoDelegate>mydelegate;
VCWithProtocol.m
`#synthesize mydelegate`
This is my class where I am trying to use my Delegate
#class VCWithProtocol;
#interface VCTOUseDelegate : UIViewController <mydemoDelegate> //here is where it shows error with cannot find protocol declaration
VCTOUseDelegate.m
VCWithProtocol *obj = [[VCWithProtocol alloc] init];
obj.mydelegate = self;
I tried with Importing VCWithProtocol but not working as well
Instead of #class VCWithProtocol; write #import VCWithProtocol.h
And some good practice Use capital letter for first character of any class name and protocol.
e.g. MyDemoDelegate and avoid retaining delegate use
#property (nonatomic,assign)id<mydemoDelegate>mydelegate;
Synthesize your mydelegate, and call
[self mydelegate];
You need to add #import "VCWithProtocol.h" to the top of your .m file.
#property (nonatomic,**weak**)id<mydemoDelegate>mydelegate;
delegate always needs weak link
I wish to create object of one class into another
I have 2 classes
MyviewControler
Checkout
I want to import Checkout into MyviewController
#import "Checkout.h"
#interface MyViewController : UIViewController <UIImagePickerControllerDelegate>
{
Checkout *checkout;
}
#property (nonatomic) Checkout *checkout;
#end
It is giving me error "Unknown type name checkout"
In MyViewController.h, before #interface add:
#class Checkout;
In MyViewController.m, add:
#import "Checkout.h"
you probably have a dependency cycle. use a forward declaration, which tells the compiler there is a class with that name without needing to see its declaration:
#class Checkout; // << the forward declaration
#interface MyViewController : UIViewController <UIImagePickerControllerDelegate>
{
Checkout *checkout;
}
#property (nonatomic) Checkout *checkout;
#end
// MyViewController.m
...
#import "Checkout.h"
forward declarations are preferred in the majority of cases. the exception to this is when there is a physical dependency (e.g. the superclass' declaration should precede the subclass'). forward declarations are good because they significantly reduce the build times and the complexity of include graphs and dependency.
good luck
If the error really is as you say:
Unknown type name checkout
(note the small 'c') then the problem is that you're using checkout as a type name instead of Checkout somewhere in your code.
import the file in MyViewController.m file too.
//in .m file
#import "Checkout.h"
#class Checkout; //this was missing
Also, give the property like this.
#property(nonatomic, retain) Checkout* checkout
and synthesize it in .m file
Slowly but surely getting this delegation and protocol stuff on iphone but I cannot understand this error.
I have declared my protocol in my first viewcontroller.
In the second viewcontroller i try to add it at the top after i have imported it into the header file and it cannot find it. see my code below.
//SendSMS
#import <UIKit/UIKit.h>
#import "LoginPage.h"
#import "MessageOptions.h"
#protocol SMSProtocol <NSObject>
-(NSString *)postbackType;
#end
#interface SendSMS : UIViewController <UITextViewDelegate, UITextFieldDelegate> {
id<SMSProtocol> delegate;
MessageOptions *messageOptions;
LoginPage *loginPage;
IBOutlet UITextField *phonenumber;
IBOutlet UITextView *smsBody;
IBOutlet UIScrollView *scrollview;
}
#property (nonatomic, retain) id<SMSProtocol> delegate;
-(IBAction)LoadMessageOptions;
#end
Then my second view
#import <UIKit/UIKit.h>
#import "SendSMS.h"
#interface ScheduledSMS : UIViewController <SMSProtocol>{
}
-(IBAction)popBack;
#end
That is surely strange. Have you tried restarting Xcode? Xcode has a habit of not indexing symbols for me when I add new files.
You should also look into how your naming conventions. SendSMS is not really a good class name, more of a action method name. I would go for SendSMSViewController, since that is what it is.
By that it would follow that SMSProtocol should be named SendSMSViewControllerDelegate, since that is what it is.
Methods in a delegate protocol should contain the sender and one of the three words will, did, or should. If not at the very least it should name what it expects to return. -(NSString *)postbackType; should probably be -(NSString *)postbackTypeForSendSMSViewController:(SendSMSViewController*)controller;.
I have the following imports in my EquivalenceClassGroup
#import "MainViewController.h"
but then in my property in EquivalanceClassGroup.h:
#property (nonatomic, assign) MainViewController *myController;
I get this error: "Expected specifier-list before MainViewController when compiling
If I change the import to: #class MainViewController and comment out the import of MainViewController.h that error goes away but then then XCode can't find the methods in my MainViewController from EquivalenceClassGroup.m so from here:
-(id)initWithLetterNumbers: (int)numOfLettersInWord enteredLetter: (NSString *) str controller:(UIViewController *)controller {
myController = (MainViewController *) controller;
letterArray = [myController getLetterArray];
[myController getLetterArray];
I get: "Method -getLetterArray not found return type defaults to id" on that last line
I have this method defined in the MainViewController: -(NSArray*)getLetterArray;
and there are no errors in that interface file or the m file. In the equivalence class if I type in [myController then space, I cant seem to find any methods.
From the MainViewController class I do import the EquivalenceClassGroup and use the methods without any problems
You have to make sure that you import the MainViewController.h file in your .m file. All the #class does is tell the interface that there is such a class, but it doesn't tell it anything about the class. That is what #import essentially does. The #class in the .h file is just good programming practice to make sure that you are doubling importing or anything. Hope that helps!
I think you have to write #import "MainViewController.h" in EquivalanceClassGroup.h file and
#class MainViewController in MainViewController.h file.
#class MainViewController
in your EquivalenceClassGroup.h
#import "MainViewController.h"
in EquivalenceClassGroup.m
This is called "forward declaration" and is quite common.
I tried searching for this issue, but can't seem to find out what I'm doing wrong.
Here is my controller header:
#import <UIKit/UIKit.h>
#interface BabyLearnViewController : UIViewController {
UIButton *btnImage;
MediaManager* myMediaManager;
}
#property (nonatomic, retain) IBOutlet UIButton *btnImage;
#property (retain) MediaManager* myMediaManager;
- (IBAction)setNewImage;
#end
Here is my controller class:
#import "BabyLearnViewController.h"
#import "MediaManager.h";
#implementation BabyLearnViewController
#synthesize btnImage;
#synthesize myMediaManager;
I am getting the errors:
error: expected specifier-qualifier-list before 'MediaManager'
error: no declaration of property 'myMediaManager' found in the interface
Any ideas? Usually the 1st error comes up if you have a cylical reference. 'MediaManager' doesn't reference anything else. Any ideas?
Since you have no mentions of MediaManager class at the moment it is used in header file compiler can't figure out what "MediaManager" is and issues an error. Declare that class using forward declaration in your header file to let compiler know that MediaManager is actually a class:
#class MediaManager;
#interface BabyLearnViewController : UIViewController {
...
P.S. As an alternative you can import MediaManager.h in your header, but using forward declaration is preferred.
Place #import "MediaManager.h"
this in header file of BabyLearnViewController
try add #class MediaManager; before #interface