iPhone SDK:在通话结束后启动应用程序

如何在应用程序内拨打电话或在通话结束后立即启动应用程序？我知道这是可能的,因为应用程序商店中的某些应用程序已经在执行此操作.

我从Apple网站获得了这个代码,它完美地工作:

-(IBAction) dialNumber:(id)sender{

NSString *aPhoneNo = [@"tel://" stringByAppendingString:[itsPhoneNoArray objectAtIndex:[sender tag]]] ; NSURL *url= [NSURL URLWithString:aPhoneNo];
 NSURL  *url= [NSURL URLWithString:aPhoneNo];
NSString *osVersion = [[UIDevice currentDevice] systemVersion];

if ([osVersion floatValue] >= 3.1) { 
UIWebView *webview = [[UIWebView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame]; 
[webview loadRequest:[NSURLRequest requestWithURL:url]]; 
webview.hidden = YES; 
// Assume we are in a view controller and have access to self.view 
[self.view addSubview:webview]; 
[webview release]; 
} else { 
// On 3.0 and below, dial as usual 
[[UIApplication sharedApplication] openURL: url];
}


}