Setting BOOL to "YES" in custom delegate - ios

Question

I've make a delegate so my two different view controllers can communicate and I'm stuck trying to set a BOOL to YES in my child view controller.
childViewController.h
#protocol pageTwoViewControllerDelegate;
#interface pageTwoViewController : UIViewController {
UIButton *takePhotoTransition;
}
#property (nonatomic, weak) id<pageTwoViewControllerDelegate> delegate;
#end
#protocol pageTwoViewControllerDelegate <NSObject>
- (BOOL)didPushTakePhoto;
#end
childViewController.m
...
- (IBAction)takePhotoTransition:(id)sender {
id<pageTwoViewControllerDelegate> strongDelegate = self.delegate;
if ([strongDelegate respondsToSelector:#selector(didPushTakePhoto)]) {
strongDelegate.didPushTakePhoto = YES; // ERROR: No setter method for 'setDidPushTakePhoto:' for assignment property
}
NSLog(#"Button push recieved");
}
How can I get past this error and set my BOOL to YES when my button is pushed?

Answer 1

The protocol is just telling everyone that knows about your class through the protocol, that the property anObject will be there. Protocols are not real, they have no variables or methods themselves
Try to modify your code to be like this, you are setting a non existence variable or property.
you have to implement new Class instead of id
your protocol will look like
#protocol pageTwoViewControllerDelegate <NSObject>
- (void)setdidPushTakePhoto:(BOOL)aBOOL;
- (BOOL)didPushTakePhoto;
#end
and your class.h will contain
#property (nonatomic, getter=get_didPushTakePhoto) BOOL didPushTakePhoto;
and your class.m will contain implementation
-(BOOL)didPushTakePhoto
{
return _didPushTakePhoto;
}
- (void)setdidPushTakePhoto:(BOOL)aBOOL{
_didPushTakePhoto=aBool;
}

Answer 2

You are getting confused between a method and a property.
The definition of your protocol "pageTwoViewControllerDelegate", says it should implement a method with name "didPushTakePhoto" which returns a BOOL value.
What you are trying to do is entirely different. You are trying to set a non-existent property. Whenever you are accessing something followed by a dot ".", that should be a property of the class to which that object belongs. The protocol you defined does not talk anything about the property.
So inside the if condition, you should be calling the method "didPushTakePhoto" on your delegate object, like below.
[strongDelegate performSelector:#selector(didPushTakePhoto)];
If you know for sure that your delegate implementations do have the protocol method implemented, then since you already cast self.delegate to strongDelegate which is declared as id, you don't need the if condition. You could directly call the method like below.
[strongDelegate didPushTakePhoto];
Hope this helps

Answer 3

Have you assigned the delegate of your ChildViewController belongs to ParentViewController?
Try this:
ParentChildViewController.m
#import "ChildViewController.h"
#interface ParentViewController () <ChildDelegate>
...
-(IBAction)btnClicked:(id)sender
{
ChildViewController *ctrl = [[ChildViewController alloc] init];
ctrl._delegate = self;
// do present childViewController or similar action here
}
- (void)didPushTakePhoto: (BOOL)result{
NSLog(#"result: %d",result);
}
ChildViewController.h
#protocol ChildDelegate
- (void)didPushTakePhoto: (BOOL)result;
#end
#interface pageTwoViewController : UIViewController {
UIButton *takePhotoTransition;
}
#property (assign, nonatomic) id _delegate;
#end
ChildViewController.m
...
- (IBAction)takePhotoTransition:(id)sender {
if ([self._delegate respondsToSelector:#selector(didPushTakePhoto:)]) {
[self._delegate didPushTakePhoto:YES];
// do dismiss here
}
}