Assigning to from incompatible type warning

Question

Assigning to id from incompatible type ''CameraVIewController*'' warning showing at the below code

 UIImagePickerController * picker = [[UIImagePickerController alloc] init];
 picker.delegate = self;

Answer 1

Actually, I think the real reason is that you miss the protocol " UINavigationControllerDelegate "

in UIImagePickerController.h you can see the delegate define:

@property(nonatomic,assign)    id <UINavigationControllerDelegate, UIImagePickerControllerDelegate> delegate;

So if you want to assign delegate like this:

picker.delegate = self;

the self viewController must implement both UINavigationControllerDelegate and UIImagePickerControllerDelegate

If you only implement UIImagePickerControllerDelegate , you can not find any error literal, but you will get a warning " Assigning to id from incompatible type ''CameraVIewController ''*", add UINavigationControllerDelegate to your viewController's protocol declaration shall get rid of it.

It's a very late answer, but I just met and solved it, hope it helps.

Answer 2

你可能没有声明你的类符合UIImagePickerController。

@interface CameraVIewController : UIViewController <UIImagePickerControllerDelegate>

Answer 3

Alternatively, you can fix the warning with a cast:

picker.delegate = (id <UIImagePickerControllerDelegate>) self;

But you have to implement UIImagePickerControllerDelegate anyway.

Answer 4

Another way is to declare private category or class extension on top of your implementation file. For example:

@interface CameraVIewController (Private) <UIImagePickerControllerDelegate>
@end