Cannot initialize parameter and I don't understand why

Question

I get this error:

Cannot initialize a parameter of type 'id<ZXingDelegate>'
with an lvalue of type 'FirstViewController *const __strong'

From this line of code:

ZXingWidgetController *widController =
    [[ZXingWidgetController alloc] initWithDelegate:self showCancel:YES
                                                           OneDMode:NO];

How can I solve this?

Answer 1

Thanks to Macmade's comment I managed to solve the problem. I should have written it this way:

ZXingWidgetController *widController =
    [[ZXingWidgetController alloc] initWithDelegate:***(id)** self showCancel:YES 
                                                                     OneDMode:NO];

Where (id) is the bridged cast he was talking about.

Answer 2

use this line off code for this issue

ZXingWidgetController *widController = [[ZXingWidgetController alloc] initWithDelegate:(id<ZXingDelegate>)self showCancel:YES OneDMode:NO];

Answer 3

If I understand this correctly, problem is not that you need bridged cast, rather your FirstViewController class is not defining ZXingDelegate interface class, thus the issue.

ZXingDelegate is (based on the name I guess) interface class (protocol, or delegate) that declares functions (interface) that must be defined by class that inherits it (unless they are @optional). Something like pure-virtual (abstract) classes in C++.

So you'd need in your header file something like this:

@interface FirstViewController : UIViewController <ZXingDelegate>

And in your .m file, something like this:

@implementation FirstViewController

//......
-(void) SomeFunctionThat_ZXingDelegate_declares
{
    // .... do something here....
}
//......


@end