网页浏览控制器错误'Expected selector for Objective C'

Question

我在创建网页浏览控制器时遇到了很多麻烦。我已经对我的代码进行了三次调整，但我不断收到以下错误："目标 C 方法的预期选择器"。我还收到另一条错误消息，显示缺少"@end"。谁能告诉我为什么我会收到这些消息？：l

    #import "InstructionContentViewController.h"
    #import "StorageViewController.h"
    @interface StorageViewController ()
    @end
    @implementation StorageViewController
    - (void)viewDidLoad
    {
    [super viewDidLoad];
    // Create the data model
    _pageTitles = @[@"Over 200 Tips and Tricks", @"Discover Hidden Features", @"Bookmark     Favorite Tip", @"Free Regular Update"];
    _pageImages = @[@"instructions1.png", @"instructions2.png", @"instructions3.png", @"instructions4.png"];
    // Create page view controller
    self.instructionViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"InstructionViewController"];
    self.instructionViewController.dataSource = self;
    InstructionContentViewController *startInstructViewController = [self viewControllerAtIndex:0];
    NSArray *viewControllers = @[startInstructViewController];
    [self.instructionViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
    // Change the size of page view controller
    self.instructionViewController.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height - 50);
    [self addChildViewController:_instructionViewController];
    [self.view addSubview:_instructionViewController.view];
    [self.instructionViewController didMoveToParentViewController:self];
     }
     - (void)didReceiveMemoryWarning
     {
      [super didReceiveMemoryWarning];
      // Dispose of any resources that can be recreated.
      }
     - (IBAction)startWalkthrough:(id)sender {
    InstructionContentViewController *startingInstructViewController = [self viewControllerAtIndex:0];
    NSArray *viewControllers = @[startingInstructViewController];
    [self.instructionViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionReverse animated:NO completion:nil];
}
#pragma mark - Page View Controller Data Source Methods:
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    NSUInteger index = ((InstructionContentViewController*) viewController).pageIndex;
    if ((index == 0) || (index == NSNotFound)) {
        return nil;
    }
      index--;
      return [self viewControllerAtIndex:index];
    }
      - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController      viewControllerAfterViewController:(UIViewController *)viewController
    {
    NSUInteger index = ((InstructionContentViewController*) viewController).pageIndex;
    if (index == NSNotFound) {
        return nil;
    }
    index++;
    if (index == [self.pageTitles count]) {
        return nil;
    }
    return [self viewControllerAtIndex:index];
    }
     - (InstructionContentViewController *)viewControllerAtIndex:(NSUInteger)index
    {
    if (([self.pageTitles count] == 0) || (index >= [self.pageTitles count])) {
        return nil;
    }
    // Create a new view controller and pass suitable data.
    InstructionContentViewController *instructionContentViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"InstructionContentViewController"];
    instructionContentViewController.instructimageFile = self.pageImages[index];
    instructionContentViewController.instructtitleText = self.pageTitles[index];
    instructionContentViewController.pageIndex = index;
    return instructionContentViewController;

    }

       - (NSInteger)presentationCountForPageViewController:(UIPageViewController     *)pageViewController
     {
    return [self.pageTitles count];
    }
    - (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController
{
    return 0;
}

     @end

Answer 1

您#import的其中一个

文件中可能存在语法错误，即InstructionContentViewController.h或StorageViewController.h。

由于导入的处理方式，警告有时会显示在意外的位置。验证这些文件以及可能从中导入的任何其他文件是否格式正确。

此外，在Xcode中，您可以单击"产品"菜单并按住"清理构建文件夹"命令的Option键。这将清除预编译的数据，并强制从头开始重新编译所有内容。