I am developing an application in which I implement a class method.h How can I access an instance variable in a class method?
Here is my instance method and an object is created of the class 'SomeClass':
-(void)viewDidLoad
{
SomeClass *obj=[SomeClass alloc] init];
}
Here is the class method and in this method I am trying to access instance variable 'obj', so I got an error saying "instance variable 'obj' accessing in class method".
+(void)classMethodImplement
{
}
You can't access instance variables from class methods. As instance variables are bound to certain instances of a class, accessing them from a class method doesn't make sense, thus the language doesn't permit it.
There is an obvious way of doing it. You just have to use static variables.
Option 1:
Store the instance variable that you want into a static variable:
static id static_iVar = nil;
- (void)viewDidLoad {
// blah, blah, blah
static_iVar = _iVar;
}
Option 2:
Store self into a static variable, then access its iVars as you like:
static id static_self = nil;
- (void)viewDidLoad {
// blah, blah, blah
static_self = self;
}
In either option, please be extremely careful. If you allocate two instances of the same class without doing proper checking and stuff, no one knows what kind of bugs could appear.
Secondly, just use the static variables in the static method:
+(void)classMethodImplement
{
// Use it here...
}
Rewrite the class method so that its caller supplies the necessary object.
+(void)classMethodImplement:(SomeClass *)obj
{
}
