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iOS

Posted by Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

Does !truefalse exist in Obj-C?

I saw some code that a person on Stack Overflow posted and it used 

!truefalse

in it, is it a bug?

2 Answers

Gabe Nadel
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STAFF
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Gabe Nadel
Treehouse Guest Teacher
Gabe Nadel
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Gabe Nadel
Treehouse Guest Teacher

Caleb,

What is !truefalse supposed to do? Does it exist in another language, if so, what does it do?

Perhaps they just created a Bool called "truefalse"?

If you link to the post I can take a peek.

Thanks!

Caleb Kleveter
MOD
Caleb Kleveter
Treehouse Moderator 37,862 Points
Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

What you said about a bool being created with that name makes sense. I put arrows on the lines with it. Here is the link to the SO post. 

-(BOOL) launchCameraControllerFromViewController: (UIViewController*) controller usingDelegate: (id <UIImagePickerControllerDelegate, UINavigationControllerDelegate>)
 ===>     BOOL truefalse = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]; 

//variable to check whether there is a camera available
//if there is a camera, the delegate passed exists, and the controller passed exists, proceed on, otherwise don't go any further
 On this line ===>            if (!truefalse || (delegate == nil) || (controller == nil)) {
                NSLog(@"no can do, delegate/camera/view controller doesn't exist!");
                return NO;
            }

            UIImagePickerController *cameraController = [[UIImagePickerController alloc] init];

            cameraController.sourceType = UIImagePickerControllerSourceTypeCamera;
            cameraController.mediaTypes = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];
            cameraController.allowsEditing = NO;
            cameraController.delegate = delegate;