在cellForRowAtIndexPath：方法中找不到属性

Question

我收到一个我不明白的错误，因为我已经宣布了这个属性。已注释掉了cellForRowAtIndexPath：方法中AllListViewController.m文件中的错误。

以下是文件：

Checklist.h

#import <Foundation/Foundation.h>

@interface Checklist : NSObject <NSCoding>

@property (nonatomic, copy) NSString *name;
@property (nonatomic, strong) NSMutableArray *items;
@property (nonatomic, copy) NSString *iconName;

-(int)countUncheckedItems;

@end

Checklist.m

#import "Checklist.h"
#import "ChecklistItem.h"

@implementation Checklist


-(id)initWithCoder:(NSCoder *)aDecoder
{
    if ((self = [super init])) {
        self.name = [aDecoder decodeObjectForKey:@"Name"];
        self.items = [aDecoder decodeObjectForKey:@"Items"];
        self.iconName = [aDecoder decodeObjectForKey:@"IconName"];
    }
    return self;
}

-(void)encodeWithCoder:(NSCoder *)aCoder
{
    [aCoder encodeObject:self.name forKey:@"Name"];
    [aCoder encodeObject:self.items forKey:@"Items"];
    [aCoder encodeObject:self.iconName forKey:@"IconName"];
}

-(id)init
{
    if ((self = [super init])) {
        self.items = [[NSMutableArray alloc] initWithCapacity:20];
        self.iconName = @"Appointments";
    }
    return self;
}

-(int)countUncheckedItems
{
    int count = 0;
    for (ChecklistItem *item in self.items) {
        if (!item.checked) {
            count += 1;
        }
    }
    return count;
}

-(NSComparisonResult)compare:(Checklist *)otherChecklist
{
    return [self.name localizedStandardCompare:otherChecklist.name];
}
@end

AllListsViewController.h

#import <UIKit/UIKit.h>
#import "ListDetailViewController.h"

@class DataModel;

@interface AllListsViewController : UITableViewController <ListDetailViewControllerDelegate, UINavigationControllerDelegate>

@property (nonatomic, strong) DataModel *dataModel;

@end

AllListsViewController.m

#import "AllListsViewController.h"
#import "Checklist.h"
#import "ChecklistViewController.h"
#import "ChecklistItem.h"
#import "DataModel.h"

@interface AllListsViewController ()

@end

@implementation AllListsViewController

- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Uncomment the following line to preserve selection between presentations.
    // self.clearsSelectionOnViewWillAppear = NO;

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;
}

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

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [self.dataModel setIndexOfSelectedChecklist:indexPath.row];

    Checklist *checklist =  self.dataModel.lists[indexPath.row];
    [self performSegueWithIdentifier:@"ShowChecklist" sender:checklist];
}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"ShowChecklist"]) {
        ChecklistViewController *controller = segue.destinationViewController;
        controller.checklist = sender;
    }
    else if ([segue.identifier isEqualToString:@"AddChecklist"]) {
        UINavigationController *navigationController = segue.destinationViewController;
        ListDetailViewController *controller = (ListDetailViewController *)navigationController.topViewController;

        controller.delegate = self;
        controller.checklistToEdit = nil;
    }
}

-(void)tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath
{
    UINavigationController *navigationController = [self.storyboard instantiateViewControllerWithIdentifier:@"ListNavigationController"];

    ListDetailViewController *controller = (ListDetailViewController *)navigationController.topViewController;

    controller.delegate = self;

    Checklist *checklist = self.dataModel.lists[indexPath.row];
    controller.checklistToEdit = checklist;

    [self presentViewController:navigationController animated:YES completion:nil];
}

#pragma mark - Table view data source


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

    // Return the number of rows in the section.
    return [self.dataModel.lists count];
}

-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    [self.dataModel.lists removeObjectAtIndex:indexPath.row];

    NSArray *indexPaths = @[indexPath];
    [tableView deleteRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationAutomatic];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {
        cell = [[UITableViewCell alloc]
                initWithStyle:UITableViewCellStyleSubtitle
                reuseIdentifier:CellIdentifier];
       cell.imageView.image = [UIImage imageNamed:Checklist.iconName]; /* Use of undeclared identifier; did you mean 'Checklist'? or Property 'iconName' not found on object of type 'Checklist'*/
        return cell;
    }

    Checklist *checklist = self.dataModel.lists[indexPath.row];
    cell.textLabel.text = checklist.name;
    cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;

    cell.detailTextLabel.text = [NSString stringWithFormat:@"%d Remaining", [checklist countUncheckedItems]];

    int count = [checklist countUncheckedItems];
    if ([checklist.items count] == 0) {
        cell.detailTextLabel.text = @"(No Items)";
    } else if (count == 0) {
        cell.detailTextLabel.text = @"All Done";
    } else {
        cell.detailTextLabel.text = [NSString stringWithFormat:@"%d Remaining", count];
    }

    return cell;
}

/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the specified item to be editable.
    return YES;
}
*/

/*
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    }   
    else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}
*/

/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
}
*/

/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the item to be re-orderable.
    return YES;
}
*/

/*
#pragma mark - Navigation

// In a story board-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}

 */

-(void)listDetailViewControllerDidCancel:(ListDetailViewController *)controller
{
    [self dismissViewControllerAnimated:YES completion:nil];
}

-(void)listDetailViewController:(ListDetailViewController *)controller didFinishAddingChecklist:(Checklist *)checklist
{
    [self.dataModel.lists addObject:checklist];

    [self.dataModel sortChecklists];
    [self.tableView reloadData];

    [self dismissViewControllerAnimated:YES completion:nil];

}

-(void)listDetailViewController:(ListDetailViewController *)controller didFinishEditingChecklist:(Checklist *)checklist
{
    [self.dataModel sortChecklists];
    [self.tableView reloadData];

    [self dismissViewControllerAnimated:YES completion:nil];
}

-(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if(viewController == self) {
        [self.dataModel setIndexOfSelectedChecklist:-1];
    }
}

-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self.tableView reloadData];
}



-(void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    self.navigationController.delegate = self;

    NSInteger index = [self.dataModel indexOfSelectedChecklist];

    if(index >= 0 && index < [self.dataModel.lists count]) {
        Checklist *checklist = self.dataModel.lists[index];
        [self performSegueWithIdentifier:@"ShowChecklist" sender:checklist];
    }
}

@end

Answer 1

您尚未声明变量“Checklist”＆amp;试图访问“iconName”。实际上，您正试图通过类名直接访问它。

如果“清单”排成几行，我可以看到你创建了一个实例。因此，在使用Checklist.iconName

之前，最好先创建该实例

创建CellIdentifier后可能在函数的开头。

    Checklist *checklist = self.dataModel.lists[indexPath.row];
    cell.imageView.image = [UIImage imageNamed:checklist.iconName]; /* Use of undeclared identifier; did you mean 'Checklist'? or Property 'iconName' not found on object of type 'Checklist'*/
        return cell;
    }

根据您的代码，“清单”是您的类名，而实例以小“c”作为“清单”开头。所以你也可能感到困惑。

希望有所帮助。