Question

我有两个VC，我想将resourceName从HomeViewController传递给SingleWebViewController。但是resourceName变为空。

HomeViewController.m

#import "HomeViewController.h"
#import "SingleWebViewController.h"

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    singleWebViewController = segue.destinationViewController;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    selectedRow = indexPath.row;

    switch (selectedRow)
    {

        case 0:
        {
            singleWebViewController.resourceName=@"intro";
            NSLog(@"HtmlFileName:%@" , singleWebViewController.resourceName);
            [self performSegueWithIdentifier:@"toSingleWebView" sender:self];
            break;
        }
        [tableView deselectRowAtIndexPath:indexPath animated:YES];
     }

SingleWebViewController.h有以下行

@property (nonatomic,strong)NSString *resourceName;
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

        NSString *htmlFile = [[NSBundle mainBundle] pathForResource:self.resourceName ofType:@"html" inDirectory:nil] ;
        NSLog(@"%@se:" , self.resourceName);

        NSURL *url = [NSURL fileURLWithPath:htmlFile    ];
        NSURLRequest *request = [NSURLRequest requestWithURL:url];
        [_webView loadRequest:request];
        _webView.delegate=(id)self;

}

我注意到在prepareForSegue之前调用了didSelectRowAtIndexPath。这是什么原因。请建议。

Answer 1

在prepareForSegue中，您要为singleWebViewController分配新内容。如果此控制器与tableView: didSelectRowAtIndexPath:中已分配的控制器不同（我认为是这样，那么您的属性将被重置）。

相反，这样做：

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    singleWebViewController = segue.destinationViewController;
    singleWebViewController.resourceName = @"intro";
}

Answer 2

您在调用resourceName后设置viewDidLoad。添加自定义初始化工具initWithResourceName:(NSString *)resourceName，然后将其设置在那里。或者将代码从viewDidLoad移至viewDidAppear:。

Answer 3

在prepareforsegue

中尝试此值

编辑：如果你想让不同的情况传递不同的值，那么就这样做...我假设你想在这里使用相同的ViewController即SingleWebViewController。

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
        {
            if ([segue.identifier isEqualToString:@"toSingleWebView"]) {
            SingleWebViewController  *singleWebViewController = segue.destinationViewController;
            NSIndexPath *indexPath = [self.tableView indexPathOfSelectedRow];
            if(indexpath.row == 0){
            singleWebViewController.resourceName=@"intro";
            }
            else if(indexPath.row == 1){
               singleWebViewController.resourceName=@"some other value";
            }
            else{
               singleWebViewController.resourceName=@"something else";
            }
            NSLog(@"HtmlFileName:%@" , singleWebViewController.resourceName);
          }
        }

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {
        selectedRow = indexPath.row;

        switch (selectedRow)
        {

            case 0:
            {

                [self performSegueWithIdentifier:@"toSingleWebView" sender:self];
                break;
            }
            case 1:
            {
                [self performSegueWithIdentifier:@"toSingleWebView" sender:self];
                break;
             }
          [tableView deselectRowAtIndexPath:indexPath animated:YES];
     }

Answer 4

尝试：

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    HomeViewController *obj = segue.destinationViewController;
    if([segue.identifier isEqualToString:@"toSingleWebView"]){
        obj.singleWebViewController = singleWebViewController;
    }
}

无法将NSString从一个VC传递到下一个VC

4 个答案: