UILabel没有更新 [英] UILabel not updating

问题描述

对不起这个基本问题，但现在这让我有些困扰。

Sorry the basic question, but this bugs me for a while now.

我从UITable创建详细信息视图并尝试动态设置其标签，但它们没有更新：

I create a details view from a UITable and try to dynamically set its labels, but they are not updating:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
  myObject *tmpObj = [[myObject objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];

  myViewController *tmpVC = [[myViewController alloc] initWithNibName:@"NIBfile" bundle:nil];

  [tmpVC.myLabel setText:tmpObj.myTitle];   // The debugger shows the text: myTitle = "myText"
  NSLog(@"%@", tmpVC.myLabel);              // NSLog SHOWS NULL

  [self.navigationController pushViewController:tmpVC animated:YES];
  [tmpObj release];
}

设置Interface Builder中的连接。文件所有者的连接选项卡显示

the connections in Interface Builder are set. The Connections Tab for File Owner shows

'myLabel' - 'Label (myLabel)'

为什么价值未通过的任何想法？

any ideas why the value is not coming through?

更多观察：

• 我还连接了IBAction。
  当我
  点击连接按钮时，正确调用此方法。


• 我得到了一些指向我的
  NSLog语句的指针，无论是$
  不能更好地使用tmpVC.myLabel.text，
  但尝试也返回NULL。


• myLabel在界面中声明为IBOutlet
  UILabel * myLabel。
  该属性定义为非原子，
  保留。

有光：

在玩了一下之后，我将pushViewController语句移到了标签更新之上。这解决了标签更新。

After playing around with it for a bit more I moved the pushViewController statement above the label updates. That resolved the label updates.

工作代码如下所示：

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
 myObject *tmpObj = [[myObject objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];

 myViewController *tmpVC = [[myViewController alloc] initWithNibName:@"NIBfile" bundle:nil];

 [self.navigationController pushViewController:tmpVC animated:YES];

 [tmpVC.myLabel setText:tmpObj.myTitle];   // The debugger shows the text: myTitle = "myText"
 NSLog(@"%@", tmpVC.myLabel);              // NSLog SHOWS NULL

 [tmpObj release];
}

但我不明白为什么我需要先推动我的viewController？ ？

But I don't understand why I need to push my viewController first ???

推荐答案

这是因为只有在访问时才会懒惰地创建控制器的视图。推送控制器访问视图。

That's because the controller's view is lazily created only when accessed. Pushing the controller accesses the view.

或者，如果你添加一行来访问view属性，它也会工作：

Alternatively, if you add a line to access the view property, it will work too:

  myViewController *tmpVC = [[myViewController alloc] initWithNibName:@"NIBfile" bundle:nil];
  tmpVC.view;   // Force view creation
  [tmpVC.myLabel setText:tmpObj.myTitle];   // The debugger shows the text: myTitle = "myText"
  NSLog(@"%@", tmpVC.myLabel);              // NSLog will display "myText"
  [self.navigationController pushViewController:tmpVC animated:YES];

这篇关于UILabel没有更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！