在视图之间传递数据不起作用

I know this question was asked about a 100 times but I just can't figure out what I'm doing wrong.

我知道这个问题被问了大约100次，但我无法弄清楚我做错了什么。

This ist my second iOS App. I want to modify a Label in my ViewControllerB by pressing a Button in my ViewControllerA.

这是我的第二个iOS应用程序。我想通过按ViewControllerA中的Button来修改ViewControllerB中的Label。

I made a Segue in Storyboard from my Button (ViewControllerA) to my ViewControllerB and called it "TestSegue".
我在Storyboard中从我的Button（ViewControllerA）创建了一个Segue到我的ViewControllerB并称之为“TestSegue”。
Wrote #import "ViewControllerB.h in my ViewControllerA.h
在我的ViewControllerA.h中写了#import“ViewControllerB.h”
I wrote this Code in my ViewControllerA.m :
我在ViewControllerA.m中编写了这段代码：

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{

- （void）prepareForSegue：（UIStoryboardSegue *）segue sender：（id）sender {

 if([segue.identifier isEqualToString:@"TestSegue"]){

ViewControllerB *controller = (ViewControllerB *)segue.destinationViewController;
controller.TestLabel.text = @"TEST!";}}
 In my ViewControllerB nothing happens with the TestLabel...
在我的ViewControllerB中，TestLabel没有任何反应......
 Can anybody see what I did wrong?
谁能看到我做错了什么？
 Thanks in advance
提前致谢
 Edit: Works now thanks to rpledge.
编辑：现在感谢rpledge。
 New Code:
新代码：

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{

if([segue.identifier isEqualToString:@"TestSegue"]){

ViewControllerB *controller = (ViewControllerB *)segue.destinationViewController;
controller.TestString = @"TEST!";}}

2 个解决方案

#1

It'l likely because the TextLabel UI element isn't created until viewDidLoad is run, which will happen after prepareForSegue:

这很可能是因为在运行viewDidLoad之前不会创建TextLabel UI元素，这将在prepareForSegue之后发生：

I don't like exposing UI elements for views publicly anyway, I would suggest you add an @property for your NSString* to the destination view controller then set the UILabel.text in viewDidLoad:

我不喜欢公开公开视图的UI元素，我建议你将NSString *的@property添加到目标视图控制器，然后在viewDidLoad中设置UILabel.text：

#2

Don't assign it to the control, but to an instance variable.

不要将它分配给控件，而是分配给实例变量。

@property (nonatomic) NSString *var;

And then in the viewDidLoad assign this to the control.

然后在viewDidLoad中将此值分配给控件。

#1