Question

I have one question about the variables of an object, I would like to know if I can check if a string is an object’s instance variable or not?
Below, an example to illustrate my issue :

I have an object – MyObject.h :

@interface MyObject :  NSObject  
{
    //Variables
    id myVariable1;
    id myVariable2;

}
@property (nonatomic, retain) id myVariable1;
@property (nonatomic, retain) id myVariable2;

And I have also an array list:

NSArray * myArray = [[NSArray alloc] initWithObjects:@"myVariable1",@"myVariable2",@"myVariable3",@"myVariable4",nil]; 

I would like to know if it’s possible to determinate which strings in the array list aren’t defined as variable in the object MyObject.
=> myVariable3 and myVariable4 for this case.

I tried to use “isKindOfClass”, “isMemberOfClass”, “valueForKeyPath”, “valueForKey” but without success… Let me know if you have some advices to resolve my problem 🙂

Answer 1

Assuming the properties aren’t using a custom setter name, you could do:

MyObject *object = ...;
for (NSString *name in myArray) {
  SEL getterName = NSSelectorFromString(name);
  if ([object respondsToSelector:getterName]) {
    NSLog(@"MyObject has a method named %@", getterName);
  } else {
    NSLog(@"MyObject does not have a method named %@", getterName);
  }
}