Question

I am trying to take a picture from my iPad app, using code I have found on the internet. I have this method:

- (BOOL) startCameraControllerFromViewController: (UIViewController*) controller
                                   usingDelegate: (id <UIImagePickerControllerDelegate,
                                                   UINavigationControllerDelegate>) delegate {

in a file called CameraViewController.m.

In CameraViewController.h, I have this definition:

@interface CameraViewController : UIViewController

+ (BOOL) startCameraControllerFromViewController: (UIViewController*) controller
                                   usingDelegate: (id <UIImagePickerControllerDelegate,
                                   UINavigationControllerDelegate>) delegate;

@end

I am trying to call it from this method which is in ClientSetupViewController.m:

    - (void) captureImage  {

        [startCameraControllerFromViewController: self usingDelegate: self];
}

I’m getting an error saying

Use of undeclared identifier startCameraControllerFromViewController

I have #import “CameraViewController.h” in CLientViewController.h

I’m totall lost! I thought I had everything defined correctly, but I guess not. What is wrong with my code?

UPDATE: getting this error now after changing code to call instance:

Undefined symbols for architecture armv7:
“_OBJC_CLASS_$_CameraViewController”, referenced from:
objc-class-ref in ClientSetupViewController.o
anon in CameraViewController.o
l_OBJC_$_CATEGORY_CameraViewController_$_CameraDelegateMethods in CameraViewController.o ld: symbol(s) not found for architecture
armv7 clang: error: linker command failed with exit code 1 (use -v to
see invocation)

Answer 1

If startCameraControllerFromViewController:usingDelegate: is indeed a class function (as indicated by the +), then the way to call the function would be:

[CameraViewController startCameraControllerFromViewController: self usingDelegate: self]

A message is sent to an object, or a class. In your code, you have just the message name in the message call [ ], with no indication of where this message should be sent to.