Objective-c, how to access an instance variable from another class

Question

I am used to programming in Java and to use class variables to access data from other classes. Then I found out that class variables does not work the same way in Obj-C, and

Answer 1

A public class variable in Java is equivalent to a global variable in C and Objective-C. You would implement it as:

class1.h

extern NSString* MyGlobalPassword;

class1.m

NSString* MyGlobalPassword = nil;

Then, anyone that imports class1.h can read and write to MyGlobalPassword.

A slightly better approach would be make it accessible via a "class method".

class1.h:

@interface Class1 : UIViewController {
    UITextField *usernameField;
    UITextField *passwordField;
    UIButton *loginButton;    
}
+ (NSString*)password;
@end

class1.m:

static NSString* myStaticPassword = nil;

@implementation Class1
+ (NSString*)password {
    return myStaticPassword;
}

- (void)didClickLoginButton:(id)sender {
    [myStaticPassword release];
    myStaticPassword = [passwordField.text retain];
}

Other classes would then read the password through the password class method.

Class2.m :

-(void) someMethodUsingPassword {
     thePassword = [Class1 password]; // This is how to call a Class Method in Objective C
     NSLog(@"The password is: %@", thePassword); 
}