iphone 截屏封存

UIGraphicsBeginImageContext(self.view.bounds.size);//UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, 0.0);[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();UIImageWriteToSavedPhotosAlbum(viewImage, self, nil, nil);