ios - 如何将解析文件传递给新的 View Controller

Question

我正在尝试将包含图像的 PFile 传递给新的 ImageView Controller ，但是我似乎无法成功传递文件。

这是我尝试传递文件的代码

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

PurchaseItemViewController*purchaseItemViewController = [[PurchaseItemViewController alloc] initWithNibName:Nil bundle:Nil];
NSLog(@"%@",indexPath);
NSInteger row = indexPath.row;

purchaseItemViewController.objectID = _objectIDArray[row];
purchaseItemViewController.imageData = _bookImageData[row];
purchaseItemViewController.authorOfBook = _authorNameArray[row];
purchaseItemViewController.titleOfBook = _bookNameArray[row];

purchaseItemViewController.bookCoverImageView.file =_bookImageData[row];

NSLog(@"HERE IS THE DATA %@",_bookImageData[row]);
NSLog(@"here is the file %@",purchaseItemViewController.bookCoverImageView.file);

[purchaseItemViewController.bookCoverImageView loadInBackground];
 // purchaseItemViewController 
// Push the view controller.
[self presentViewController:purchaseItemViewController animated:NO completion:Nil];

}

当我执行代码时，我得到以下注销

016-02-09 14:36:33.265 ParseStarterProject[17786:7270793] 这是数据“PFFile:0x7fbe12f7dcb0”

2016-02-09 14:36:33.266 ParseStarterProject[17786:7270793] 这里是文件(空)

谁能告诉我我做错了什么？
谢谢

Answer 1

问题是 View Controller 在代码运行时还没有准备好配置它的 View (例如 bookCoverImageView )。

正确的步骤顺序是构建 purchaseItemViewController正如您所做的那样，从您的数据源设置属性，然后呈现它。不要尝试配置其 View 或加载图像。

PurchaseItemViewController*purchaseItemViewController = [[PurchaseItemViewController alloc] initWithNibName:Nil bundle:Nil];
NSLog(@"%@",indexPath);
NSInteger row = indexPath.row;

purchaseItemViewController.objectID = _objectIDArray[row];
purchaseItemViewController.imageData = _bookImageData[row];
purchaseItemViewController.authorOfBook = _authorNameArray[row];
purchaseItemViewController.titleOfBook = _bookNameArray[row];

// TOO EARLY FOR THIS:  
// purchaseItemViewController.bookCoverImageView.file =_bookImageData[row];

NSLog(@"HERE IS THE DATA %@",_bookImageData[row]);
// TOO EARLY FOR THIS:
// NSLog(@"here is the file %@",purchaseItemViewController.bookCoverImageView.file);

//  TOO EARLY FOR THIS:
// [purchaseItemViewController.bookCoverImageView loadInBackground];
[self presentViewController:purchaseItemViewController animated:NO completion:Nil];

您必须配置 View 的第一个机会是 PurchaseItemViewController , 在 viewDidLoad .在那里，你可以说...

PFFile *file = self.imageData;  // this is a PFFile with a confusing name
self.bookCoverImageView.file = file;
[self.bookCoverImageView loadInBackground];