Schogini

If, you get a message like this:  “Please enter a valid credit card verification number.” every time you enable “CVV check” in your payment gateway, and you are sure that your payment module settings are correct and your card details are valid then, its most likely that the message is not coming from your payment module.

Instead it could be that the control is not reaching the payment module at all and the message is coming from this Magento file:
app/code/core/Mage/Payment/Model/Method/Cc.php line #150, validate credit card verification number section.

Why is this happening? Does this error occur for ‘Saved CC’ payment method too (it is the default card payment method got with Magento)?

Well, one reason that I found is – custom checkout module. Are you using any custom checkout module? If yes, then disable it and try the normal Magento one page checkout. The chances are all will work fine. I have noticed that some custom checkout modules fail to send the CVV number back to the code – hence, Magento will catch it and throw back the error – the payment module is nowhere in the picture yet.

So, before you panic that your card details are invalid or your Payment Gateway or payment module is not working, confirm that it is not your custom checkout module that is the culprit.

You need to have a set of global variables and functions that can be accessed through all classes – how do you do it in Objective C?

Objective C doesn’t understand the concept of global functions or variables as such – you need to go the objective programing way to simulate global functionality.

There are 2 solutions for this:

1. Use the AppDelete class
2. Create your own singleton class

Basically, both the solutions are the same since the AppDelegate class is also a singleton class.

Here, I will explain solution #2 (its not good programing practice to write business logic in the AppDelegate)

First, what is a singleton class? A class that can have ONLY one instance throughout the program is called a singleton class. It means, if you have created an object of a singleton class, when you try to create a new object it will not create it! Instead it will return the reference of the first object.

We can use this feature to simulate global functionality – there can be only one instance of this class hence, the properties and methods defined in the class can be accessed across classes without any change in values.

For, a more detailed explanation you can checkout this wiki link: http://en.wikipedia.org/wiki/Singleton_pattern

Now, lets get to the actual code. I assume you already know how to create a project in XCode and have a simple project ready.

Step 1: Open your XCode project and add a new class.

In your XCode > ‘Group & Files’ colum > Right click on the classes folder > Click ‘Add > New File..’ > Select ‘Objective-C class’ (ensure its a sub class of NSObject) > Click ‘Next’ > Enter the new class name (in this example, GlobalData) > Finish

Step 2: The .h file

This is the interface file

@interface GlobalData : NSObject {
NSString *message; // global variable
}

@property (nonatomic, retain) NSString *message;

+ (GlobalData*)sharedGlobalData;

// global function
- (void) myFunc;

@end

Step 3: The .m file

This is the implementation file

#import "GlobalData.h"

@implementation GlobalData
@synthesize message;
static GlobalData *sharedGlobalData = nil;

+ (GlobalData*)sharedGlobalData {
    if (sharedGlobalData == nil) {
        sharedGlobalData = [[super allocWithZone:NULL] init];

	// initialize your variables here
	sharedGlobalData.message = @"Default Global Message";
    }
    return sharedGlobalData;
}

+ (id)allocWithZone:(NSZone *)zone {
	@synchronized(self)
	{
		if (sharedGlobalData == nil)
		{
			sharedGlobalData = [super allocWithZone:zone];
			return sharedGlobalData;
		}
	}
	return nil;
}

- (id)copyWithZone:(NSZone *)zone {
    return self;
}

- (id)retain {
    return self;
}

- (NSUInteger)retainCount {
    return NSUIntegerMax;  //denotes an object that cannot be released
}

- (void)release {
    //do nothing
}

- (id)autorelease {
    return self;
}

// this is my global function
- (void)myFunc {
	self.message = @"Some Random Text";
}
@end

Step 4: How to use it

In the implementation file of the class where you want to use the global variable or function include the GlobalData.h file

#import "GlobalData.h"

To access the global variable (that is the singleton class property) do this:

[GlobalData sharedGlobalData].message

GlobalData is our class name, sharedGlobalData is a class method which will check if there is already an instance for this class – if so, it will return that else, it will create a new instance and return it. “message” is the name of our class property – which we are going to use as a global variable

To access the global function (that is the singleton class method) do this:

[[GlobalData sharedGlobalData] myFunc];

Just like before, we get the singleton object and then call its method – which we are going to use as a global function.

In this way you can include the GlobalData.h file in any number of classes and use the variables and functions – the variable values will be shared between all the classes.

Hope you find this useful…let me know your feedback!

Reference links:

http://developer.apple.com/library/mac/#documentation/General/Conceptual/DevPedia-CocoaCore/Singleton.html

http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CocoaFundamentals/CocoaObjects/CocoaObjects.html%23//apple_ref/doc/uid/TP40002974-CH4-SW32

EDIT: This article is applicable for Magento versions 1.5.0.1 too

The latest 1.4.x series of Magento has some small changes/enhancements which are not exactly backward compatible. This is especially true with themes.

As payment module developers, we get a lot of people coming back saying that after upgrade or fresh installation of the latest version, the payment step on the one page checkout doesn’t work.

If, you have a custom theme installed and, after upgrade, you find that your checkout is not working – that is after entering your credit card information and click ‘Next’ nothing happens – follow these steps: More »

Got this nice extension which puts a ‘Newsletter Sign-up’ check-box on the Magento checkout page.

http://www.magentocommerce.com/magento-connect/QuickModules/extension/1361/checkout-newsletter/

Due to permission restrictions I was not able to connect to the Magento Connect Manager link on my live cart. So I went ahead and installed it on my localhost Magento. Here are the steps: