Question

I’m developing an in iOS6 and using Xcode 4.5.2.

I’ve a UIViewController,let’s say its name is aViewController. In this UIViewController, i’ve a BOOL pointer declared as a property using this code. Actually, it’s not a piece of code i’ve implemented, so i don’t really know why BOOL pointer is used.

Now, when assigning a value to this BOOL pointer, i got this famous warning Incompatible integer to pointer conversion assigning to 'BOOL *' (aka 'signed char *') from 'signed char' which is totally understandable because in my case,BOOL points to a boolean variable.

To resolve this problem, i’ve tried this one.So my code was like this:

aViewController.aBoolPointer = YES;

Then, i’ve tried ,

aViewController.(*aBoolPointer) = YES;

As Objective-c is a super set of C, i remember that in C .* notation is equal to ->. And the above notation gives an error.Error description : Identifier expected .

If i change code to like this :

aViewController->aBoolPointer = YES ;

I got this error Instance variable aBoolPointer is protected.

Here is the weird issue, if i use this code

aViewController.aBoolPointer = NO ;

Then, i got no warning.

So my questions are :

1-Why i got no warning when i assign NO value to a BOOL pointer ?

2-How can i properly assign YES value to BOOL pointer ?

3-What is the difference between YES or NO by considering the steps i explained ?

Thank you,all.

Answer 1

1 Why i got no warning when i assign NO value to a BOOL pointer ?

Because NO is the same as 0, or NULL, so it’s like assigning a NULL to the pointer, as in:

BOOL *p = NULL;

2 How can i properly assign YES value to BOOL pointer ?

If the property is defined as:

@property(assign, nonatomic) BOOL *boolp;

Then:

BOOL b = YES;
obj.boolp = &b;

3 What is the difference between YES or NO by considering the steps i explained ?

I don’t understand the question.