创建一个image 

接着创建一个view

UIImage *image = [UIImage imageNamed:@""];

UIImageView *imageview = [[UIImageView alloc]init];

imageview.frame = CGRectMake(0, 0, 222, 333);

imageview.image = image;

[self.view addSubview:imageview];

把图片放到uiimagepngpresentation里面进行数据转换

然后存储，简单的步骤就完成了

UIImage *image = [UIImage imageNamed:@""];

NSData *data = UIImagePNGRepresentation(image);

UIImage *imagepng = [UIImage imageWithData:data];

UIImageWriteToSavedPhotosAlbum(imagepng, nil, nil, nil);