Question

我在将单元格插入到我的TableView时遇到问题，我怀疑它是因为我的viewController未被识别为委托。我通过storyboard设置viewController并将其类设置为我的自定义ItemViewController类。我的视图控制器设置如下：

#import "ItemsViewController.h"
#import "DetailViewController.h"
#import "ItemCell.h"
#import "Item.h"
#import "ItemStore.h"

@implementation ItemsViewController

//designated initializer
-(instancetype) initWithStyle:(UITableViewStyle)style {
    return [self init];
}

-(void) viewDidLoad {
    self.tableView.delegate = self;
    self.tableView.dataSource =self;
}

-(void) viewWillAppear:(BOOL)animated {
    //execute the super code in case there's work to be done by it
    [super viewWillAppear:YES];

    //reload the data to reflect any changes made either by a user or the program
    [self.tableView reloadData];

}

-(void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    //create a detail view controller and initiate it with the selected item
    DetailViewController *dvc = [[DetailViewController alloc] init];
    NSArray *store = [[ItemStore sharedStore] allItems];
    Item *selectedItem = store[indexPath.row];
    dvc.item = selectedItem;

    //push the detail view controller onto the nav controller
    [self.navigationController pushViewController:dvc
                                     animated:YES];


}

-(void)  tableView:(UITableView *)tableView
moveRowAtIndexPath:(NSIndexPath *)sourceIndexPath
       toIndexPath:(NSIndexPath *)destinationIndexPath {

    //move item from one index to another in the table
    [[ItemStore sharedStore] moveItemAtIndex:sourceIndexPath.row
                                     toIndex:destinationIndexPath.row];
}


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

    //number of rows in the table. will adjust with every new item added
    return [[[ItemStore sharedStore] allItems] count];
}


-(UITableViewCell *)tableView:(UITableView *)tableView
        cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    //set up the cell
    NSString static *cellIdentifier = @"itemCell";
    ItemCell *newCell = [tableView    dequeueReusableCellWithIdentifier:cellIdentifier];

    if (newCell == nil) {
        newCell = [[ItemCell alloc]   initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
    }

    //retrieve the item at the appropriate index
    NSArray *items = [[ItemStore sharedStore] allItems];
    Item *newItem = items[indexPath.row];

    newCell.nameLabel.text = newItem.itemName;
    newCell.serialLabel.text = newItem.serialNumber;
    newCell.valueLabel.text = [NSString stringWithFormat:@"%d",    newItem.value];

    return newCell;
}


- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    //create an empty item object
    Item *newItem = [[ItemStore sharedStore] createItem];
    NSArray *itemStore = [[ItemStore sharedStore] allItems];

    //insert a row with the appropriate path
    NSIndexPath *path = [NSIndexPath indexPathForRow: [itemStore count]
                                       inSection:0];

    [self.tableView insertRowsAtIndexPaths:@[path]
                      withRowAnimation:UITableViewRowAnimationTop];
    DetailViewController *dvc = segue.destinationViewController;
    dvc.item = newItem;
}

和我的故事板如此：

我的意图是，当用户点击＆＃34;添加项目＆＃34;时，会在tableView中创建一个新的单元格以及一个空的Item对象，我将传递给（DetailViewController）我的segue - 到。

当我尝试运行此代码时，我收到错误：＆＃34;由于未捕获的异常终止应用程序＆＃39; NSInternalInconsistencyException＆＃39;，原因：＆＃39;尝试将第1行插入到部分0，但更新后第0部分只有1行＆＃39;＆＃34; 从我在线阅读的内容这是因为数据源/代理人没有返回正确的数字＆＃34; numberOfRowsInSection＆＃34;中的行数。我的项目的来源（itemStore，item）都很好，调试器证明了这一点。

有人对此有任何意见吗？我为tableView设置委托/数据源是错误的吗？

编辑：提供故事板截图并解释＆＃34;添加项目＆＃34;接口

Answer 1

我认为，您正在尝试创建错误的 NSIndexPath 。试试这个：

 - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
        //create an empty item object
        Item *newItem = [[ItemStore sharedStore] createItem];
        NSArray *itemStore = [[ItemStore sharedStore] allItems];

        //insert a row with the appropriate path
        NSIndexPath *path = [NSIndexPath indexPathForRow: ([itemStore count]-1)
                                           inSection:0];

        [self.tableView insertRowsAtIndexPaths:@[path]
                          withRowAnimation:UITableViewRowAnimationTop];
        DetailViewController *dvc = segue.destinationViewController;
        dvc.item = newItem;
    }

UITableView数据源和委托的问题

1 个答案: