I noticed that on the latest angry birds update they added a feature to gift your app from inside the app.
Up till now I knew you can gift paid apps from the iTunes
I have here some step-by-step instructions in how to add a 'Gift This App' button into your app:
Add a button in your XIB and add an action to it.
In your .m add the actions brackets e.g:
-(IBAction)actionName {
}
add this code in and replace APP_ID with the number in the apps web page link for e.g.
itunes.apple.com/au/app/[APPNAME]/id**APP_ID**?mt=8
this is a code e.g:
- (IBAction)actionName
{
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"https://buy.itunes.apple.com/WebObjects/MZFinance.woa/wa/giftSongsWizard?gift=1&salableAdamId=**[APP_ID]**&productType=C&pricingParameter=STDQ"]];
}
Hope this helps!