CODEWITHSUNDEEP
iosobjective-cxcode
blindman457
blindman457

Reputation: 293

Can't 'nil' a variable xcode

Trying to 'nil' some double variables... but getting the 'Assigning to 'double' from incompatible type 'void *' error...

This is my properties (trying to make a variable type class, that holds global vars so they can be accessed and changed from anywhere in the app):

@property (nonatomic) CGPoint lastP;
@property (nonatomic) double brushR;
@property (nonatomic) double brushG;
@property (nonatomic) double brushB;
@property (nonatomic) double brushW;
@property (nonatomic) double brushO;
@property (nonatomic) BOOL mouseSwiped;

then I synthesis like so: @Synthesis lastP; @Synthesis brushR; etc, etc,

and when I do a cleanup method (as I'm exiting the view and going back to a menu) and try and nil the vars so they can be deallocated via arc brushR = nil; brushG = nil; lastP = nil; etc, etc I get the error I stated above.

Is it easier to just use [view removefromsuperview] in the parent viewcontroller (as all this information is going into a containerView INSIDE of a view controller (that's the way it needs to be, can't get around this)) and will that kill all the variables from the above calss? or do I need to nil them manually?

if I can just use removefromsuperview (from a parent class) (eg, I have a view controller and then a container view inside that controller, when a button is pushed in the PARENT controller, the app uses [childcontroller removefromsuperview]) will that 'kill' ALL objects being used by the childview (as I have a uiImage inside the childview view and it didn't seem to clear the image it was holding from memory when I tried this method).

if I have to nil my vars (and not just nuke the view and remove it from the hirachy) why isn't it letting me do this?

I really hope I'm understandable.

Upvotes: 0

Views: 568

Answers (5)

Mritunjay
Mritunjay

Reputation: 167

Since Double is primitive type , therefore ,we cannot set it as nil. nil or Nil can be set to ObjectType Variable.

Upvotes: 1

Evol Gate
Evol Gate

Reputation: 2257

For id type objects you use nil. Otherwise for void * (ie a C-style pointer) you can use NULL/ nil

Use brushR = 0; then it should be fine.

Upvotes: 1

Mani
Mani

Reputation: 17595

You cann't do this. You can only set nil to pointers. Primitives cann't fill with nil/NULL. You may assign simple zero in these place.

Upvotes: 1

Andrey Gordeev
Andrey Gordeev

Reputation: 32559

Is it easier to just use [view removefromsuperview] in the parent viewcontroller (as all this information is going into a containerView INSIDE of a view controller (that's the way it needs to be, can't get around this)) and will that kill all the variables from the above calss? or do I need to nil them manually?

If you use ARC, you don't need to do a cleanup. Runtime will do that for you.

I have a uiImage inside the childview view and it didn't seem to clear the image it was holding from memory when I tried this method

It will be released as long as there are no other strong references to it.

Upvotes: 1

Peter Segerblom
Peter Segerblom

Reputation: 2823

You can never nil primitives only pointers. To explain. nil is of type "void *" and you can not assign void * to type float, double etc. you can only assign void * to pointer types. Since a pointer is an address to some memory when you assign nil to the pointer you are pointing the pointer to some memory space that are reserved for nil.

Upvotes: 1

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