Objective c 必须使用；结构"；标签指的是“类型”；标签"；

我遇到一个错误，必须使用“struct”标记引用类型“label” 什么是不正确的？？我在出现错误的地方用注释标记。我的Xcode版本是5.0.2 /////////////////////////////////////////////////////////////////////////////////////////////// m

h

#导入
@界面GameViewController:UIViewController
@属性（弱，非原子）IBUILabel*标签；
@属性（弱，非原子）IBUITEXTFIELD*答案；
-（iAction）提交：（id）发件人；
@结束

试试

self.label.text

或

\u label.text

谢谢，它奏效了，但我不明白，label和\u label只是不同的变量？它是如何工作的？）我不确定标签是什么，以及为什么会出现这种错误。通常，您会看到的错误是这个变量未定义，它也会向您推荐我推荐的两个变量之一。

  #import "GameViewController.h"

@interface GameViewController ()

@end

@implementation GameViewController

-(void)generate{
    int a=1+arc4random() % 9;
    int b=1+arc4random() % 9;

    int sum=a+b;
    label.text = [NSString stringWithFormat:@"%d + %d = ", a, b]; //here is error
    label.tag=sum;  //and here

}
- (void)viewDidLoad
{
    [super viewDidLoad];
    [self generate];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)submit:(id)sender {
    int num=[_answer.text intValue];
    UIAlertView *alert;
    if(num == _label.tag){
        alert=[[UIAlertView alloc]initWithTitle:@"Correct" message:@"Let's try another one!" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        alert.tag =1;
    }else{
        alert =[[UIAlertView alloc]initWithTitle:@"Wrong!" message:@"That answer is incorrect" delegate:self cancelButtonTitle:@"Try again" otherButtonTitles:nil, nil];
    }
    [alert show];
}

@end

#import <UIKit/UIKit.h>

@interface GameViewController : UIViewController
@property (weak, nonatomic) IBOutlet UILabel *label;
@property (weak, nonatomic) IBOutlet UITextField *answer;

- (IBAction)submit:(id)sender;
@end