导航控制器有时会使用情节提要推送到黑屏

Question

我在 Xcode 5 中使用故事板，我试图从 UINavigationController 中的 UITableViewController 推送到 UIViewController，但有时会出现黑屏（可能有 75% 的时间）。通过阅读其他帖子，我学会了使用instantiateViewControllerWithIdentifier: 方法在推送之前实例化我正在推送的视图控制器，所以我的代码如下所示：

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    [tableView deselectRowAtIndexPath:indexPath animated:YES];
    if (indexPath.row < self.objects.count) {
        PFObject *retrievedProduct = [self.objects objectAtIndex:indexPath.row];
        Product *product = [[Product alloc] init];

        // set properties for retrieved product 
        // (code omitted)

        //load product detail page
        self.detailPage = [[UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]] instantiateViewControllerWithIdentifier:@"MPDetailPageViewController"];
        self.detailPage.product = product;

        //Bring to detail page
        [self.navigationController pushViewController:self.detailPage animated:YES];

    } else if (self.paginationEnabled) {
        // load more
        [self loadNextPage];
    }
}

在 MPDetailPageViewController 中，我在 viewDidAppear 中执行 NSLog，即使屏幕为黑色，它仍在打印。

任何建议将不胜感激。

谢谢， 蒂姆

Answer 1

看看这是否适合你：

首先确保头文件被导入：

#import "MPDetailPageViewController.h"

然后这样做：

//the storyboard
UIStoryboard *storyboard = self.navigationController.storyboard;

//the detail controller
MPDetailPageViewController *detailPage = [storyboard 
           instantiateViewControllerWithIdentifier:@"MPDetailPageViewController"];
//set the product
detailPage.product = product;
//Push to detail View
[self.navigationController pushViewController:detailPage animated:YES];

PROJECT NO SEGUE

---

除非你真的必须这样做，否则以编程方式推送视图会更困难（更多代码）。

只需在故事板中创建一个segue，如果您不确定，请参考one of my answers。

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    //[tableView deselectRowAtIndexPath:indexPath animated:YES];
    if (indexPath.row < self.objects.count) {
        //perform the segue
        [self performSegueWithIdentifier:@"detailSegue" sender:sender];
    } else if (self.paginationEnabled) {
        // load more
        [self loadNextPage];
    }
}

现在您可以将所有其他代码移至以下 segue 委托：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Make sure your segue name in storyboard is the same as this line
 if([segue.identifier isEqualToString:@"detailSegue"]){
    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
    PFObject *retrievedProduct = [self.objects objectAtIndex:indexPath.row];
    Product *product = [[Product alloc] init];

    MPDetailPageViewController *detailVC = (MPDetailPageViewController *)segue.destinationViewController;
    detailVC.product = product;
 }
}

PROJECT USING SEGUE