CODEWITHSUNDEEP
iosobjective-cswift
Barkley
Barkley

Reputation: 6693

How to access a private objective C variable in Swift View Controller?

I've got next to no knowledge about Objective-C. I'm working with an Obj-C framework for an AVCaptureSession. I need to have access to the AVCaptureVideoDataOutput of the camera's session.

In the .m file the session is initialized and set up. 

@property (nonatomic, strong) AVCaptureSession *session;

I cannot move the property from the .m to .h file because the .m file needs it for all of the functions to set it up.

I also tried making them readwrite / readonly in the .m and .h respectively to avoid a redeclaration issue, but then when I call on the camera.session after I'm starting the camera up, "session" returns nil and the app crashes.

I don't know if there would be any problem just moving all of the code into the .h file so it's all publicly accessable?

How can I access the session property from a .m file in my View Controller?

Upvotes: 2

Views: 311

Answers (2)

Patrick
Patrick

Reputation: 2382

Moving the property to the .h. exposes it publicly and also makes it available to the .m because the .m file by default imports the .h. Example:

// CameraViewController.h
@interface CameraViewController : UIViewController
@property (nonatomic, strong) AVCaptureSession *session;
@end 

// CameraViewController.m
#import "CameraViewController.h" // <- notice the import, `session` is accessible internally.

As for the session property being nil it may be because you have not initialized it with a value yet. In your init you may want to initialize session with [[AVCaptureSession alloc] init]

Note: to avoid potential problems with unintended mutability I recommend asking your self if you can make publicly exposed properties read only i.e.

@property (nonatomic, strong, readonly) AVCaptureSession *session;

Upvotes: 2

Haagenti
Haagenti

Reputation: 8144

If you move it to the .h the .m has access to it as well. You can even make it readonly in the header and readwrite in the m

So do either:

.h:

@property (nonatomic, strong) AVCaptureSession *session;

Or:

.h:

@property (nonatomic, strong, readonly) AVCaptureSession *session;

.m:

@property (nonatomic, strong, readwrite) AVCaptureSession *session;

Upvotes: 1

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