Question

我正在使用BigNerdRanch ios应用程序书。在第一章中，它创建了一个小问答应用程序，将问题硬编码到代码文件中。如果应用程序成功运行，它应该在控制台中说displaying question: "What is blah blah?"，但是当我运行应用程序时它会说

displaying question: (null)

换句话说，（null）出现而不是数组中的问题。

编译时没有错误显示。我想知道是否与我的XCode使用Main.storyboard文件而不是xib和nib文件这一事实有关，结合视图控制器使用似乎期望nib文件的方法的事实，即

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:

任何帮助将不胜感激。这就是所有的代码。

iosQuizViewController.h

#import <UIKit/UIKit.h>

@interface iosQuizViewController : UIViewController

iosQuizViewController.h

{
    int currentQuestionIndex;

    NSMutableArray *questions;
    NSMutableArray *answers;

    IBOutlet UILabel *questionField;
    IBOutlet UILabel *answerField;
}

- (IBAction)showAnswer:(id)sender;
- (IBAction)showQuestion:(id)sender;

@end

iosQuizViewController.m

#import "iosQuizViewController.h"

@interface iosQuizViewController ()

@end

@implementation iosQuizViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        questions = [[NSMutableArray alloc] init];
        answers = [[NSMutableArray alloc] init];
        [ questions addObject:@"What is 7 +7"];
        [ answers addObject:@"14"];

        [questions addObject:@"What is the capital of Vermont?"];
        [answers addObject:@"Montpelier"];

        [questions addObject:@"From what is cognac made?"];
        [answers addObject:@"Grapes"];

    }
    return self;
}

- (IBAction)showQuestion:(id)sender
{
    currentQuestionIndex++;
    if (currentQuestionIndex == [ questions count] ){
        currentQuestionIndex = 0;
    }
    NSString *question = [ questions objectAtIndex:currentQuestionIndex];
    NSLog(@"displaying question: %@", question);
    [questionField setText: question];
    [answerField setText:@"???"];

}

- (IBAction)showAnswer:(id)sender
{
    NSString *answer = [ answers objectAtIndex:currentQuestionIndex];

    [answerField setText:answer];
}


@end

Answer 1

我删除了initWithNibName：bundle方法并将该代码放在viewDidLoad中

- (void)viewDidLoad
{
    if (self)
    {
        // Create two arrays and make the pointers point to them
        questions = [[NSMutableArray alloc] init];
        answers = [[NSMutableArray alloc] init];

        // Add questions and answers to the array
        [questions addObject:@"What is 7 + 7?"];
        [answers addObject:@"14"];

        [questions addObject:@"What is the capital of Vermont?"];
        [answers addObject:@"Montpelier"];

        [questions addObject:@"What is cognac made from?"];
        [answers addObject:@"Grapes"];
    }

}

数组的元素为null

1 个答案: