从子类访问Root类中的变量的值 [英] Accessing the value of a variable in the Root class from a subclass

问题描述

我真的不能算出这个。
我有一个VC名为additionalMathViewController，向用户显示问题。如果用户回答不正确，则用户被引导到另一个VC，该VC是additionalMathViewController的子类，称为incorrectViewController。

I really can not figure this one out. I have a VC called additionalMathViewController which displays questions to the user. If the user answers incorrectly the user is directed to another VC which is a subclass of additionalMathViewController called incorrectViewController.

#import "ViewController.h"
@interface additionalmathViewController : ViewController{
int currentQuestion;
}

currentQuestion是一个计数器变量，增加用户获取问题的权利，问题可以显示。如果用户得到错误的问题，我想去wrongViewController。这是我的代码

currentQuestion is a counter variable which increases everything the user gets a question right and another question can be displayed. if the user get the question wrong I want to go to incorrectViewController. Here is my code

- (IBAction)SelectA:(id)sender {
if ([self.correctAns isEqualToString:@"A"]) {
       [self showNextQuestion];
}
else{
  [self performSegueWithIdentifier: @"segueToIncorrect" sender:nil];
}
}

如果用户选择A，题。如果它是错误的执行segue到incorrectViewController

If the user selects A and it is correct show another question. If it is wrong perform Segue to incorrectViewController

#import "additionalmathViewController.h"
@interface IncorrectImageViewController : additionalmathViewController

这里我想从additionalMathViewController获取currentQuestion的值

Here I want to grab the value of currentQuestion from additionalMathViewController

incorrectImage.image = [UIImage imageNamed:left[currentQuestion]];

此当前图像不是来自additionalmathViewController的值

This current image is not the value from the additionalmathViewController

任何想法？

推荐答案

新的视图控制器是一个新实例，因此不知道上一个实例为一个值。您需要在 prepareForSegue 方法中将您的currentQuestion值传递给新控制器。

The new view controller is a new instance, therefore has no idea what the previous instance had for a value. You need to pass your currentQuestion value to the new controller in prepareForSegue method.

将currentQuestion作为属性

Make currentQuestion a property

@interface IncorrectImageViewController
  @property (copy) NSInteger currentQuestion;
..

然后在prepareForSegue中设置目标控制器上的值。 p>

And then in the prepareForSegue set the value on the destination controller.

@implementation additionalmathViewController

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    IncorrectImageViewController *incorrect = [segue destinationViewController];
    incorrect.currentQuestion = self.currentQuestion;
}

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