Are static variables in Objective-C methods shared across instances?

Question

I want to clarify whether different instances of an Objective-C class share static variables that occur inside methods, or if each instance gets its own copy:

- (void) myMethod {     static int myVar = 0; } 

Answer 1

Static locals are shared between method calls AND instances. You can think of them as globals which are visible only inside their methods:

- (void) showVars {     int i = 0;     static int j = 0;     i++; j++;     NSLog(@"i = %i ; j = %i", i, j); } 

[...]

[obj1 showVars]; [obj2 showVars]; [obj1 showVars]; [obj2 showVars]; 

Above calls on 2 different instances will output:

i = 1 ; j = 1 i = 1 ; j = 2 i = 1 ; j = 3 i = 1 ; j = 4 

Answer 2

It's the same as a static variable in C; the instances will share the variable. If you want each instance to have its own copy, you want an instance variable (declared in the @interface block).