Taking Screenshot programatically in iOS

if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
    UIGraphicsBeginImageContextWithOptions(self.window.bounds.size, NO, [UIScreen mainScreen].scale);
} else {
    UIGraphicsBeginImageContext(self.window.bounds.size);
}

[self.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData * data = UIImagePNGRepresentation(image);
[data writeToFile:@"foo.png" atomically:YES];