Question

首先，我的问题是严肃的＆amp;不适合那些只愿意分配负面反馈或只是在这里进行编辑的人获得奖励目的。

我的问题传达起来很复杂，但我正在尽力传达完整的问题。实际上我在后端有两个表视图和两个Json文件，还有一个AVPlayerViewController。首先，alll firstTableViewController显示第一个包含以下Json数据的json文件

    [{
    "id": "0",
    "name": "Religion"
}, {
    "id": "1",
    "name": "News"
}, {
    "id": "2",
    "name": "Sport"
}, {
    "id": "3",
    "name": "Doc"
}, {
    "id": "4",
    "name": "Kids"
}, {
    "id": "5",
    "name": "Music"
}, {
    "id": "6",
    "name": "Movie"
}, {
    "id": "7",
    "name": "Entr"
}, {
    "id": "8",
    "name": "Cooking"
}, {
    "id": "9",
    "name": "All"
}]

在SecondViewController中，它提取包含不同链接的second Json file以及上面第一个json文件中提到的类别。在我的应用程序中成功检索到两个Json File的数据。

当我单击我的FirstTableViewController的任何单元格（包含特定类别）时，它会将我带到secondTableViewController，其中包含该特定类别的所有对象的title属性（在第二个json文件中命名为category_name）选定的类别。到这里一切都很酷。但是当我以前点击任何标题时出现的问题应该把我带到AVPlayerViewController并播放相关的直播链接。但它给了我以下错误，

*由于未捕获的异常'NSRangeException'而终止应用，原因：'* - [ NSArrayM objectAtIndex：]：索引2097174超出范围   [0 .. 32]'   ***第一次抛出调用堆栈：（0 CoreFoundation 0x0000000104b0234b __exceptionPreprocess + 171 1 libobjc.A.dylib
  0x000000010456321e objc_exception_throw + 48 2 CoreFoundation
  0x0000000104a33f1b - [__ NSArrayM objectAtIndex：] + 203 3 AlbTVRadio   0x00000001022bcae1 - [第二次prepareForSegue：发送者：] + 321 4 UIKit   0x0000000102bbef5f - [UIStoryboardSegueTemplate   _performWithDestinationViewController：sender：] + 353 5 UIKit 0x0000000102bbedcd - [UIStoryboardSegueTemplate _perform：] + 82 6
  UIKit 0x0000000102bbf08f    - [UIStoryboardSegueTemplate执行：] + 156 7 UIKit 0x000000010253b52a - [UITableView   _selectRowAtIndexPath：animated：scrollPosition：notifyDelegate：] + 1769 8 UIKit 0x000000010253b78d    - [UITableView _userSelectRowAtPendingSelectionIndexPath：] + 330 9 UIKit 0x00000001023f12eb   _runAfterCACommitDeferredBlocks + 320 10 UIKit 0x00000001023ddf6f _cleanUpAfterCAFlushAndRunDeferredBlocks + 566 11   UIKit 0x000000010240f3da   _afterCACommitHandler + 176 12 CoreFoundation 0x0000000104aa6e17   __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION + 23 13 CoreFoundation 0x0000000104aa6d87   __CFRunLoopDoObservers + 391 14 CoreFoundation 0x0000000104a8bb9e __CFRunLoopRun + 1198 15 CoreFoundation
  0x0000000104a8b494 CFRunLoopRunSpecific + 420 16 GraphicsServices
  0x0000000106784a6f GSEventRunModal + 161 17 UIKit
  0x00000001023e4964 UIApplicationMain + 159 18 AlbTVRadio
  0x00000001022cd65f main + 111 19 libdyld.dylib
  0x000000010a00968d开始+ 1 20 ???   0x0000000000000001 0x0 + 1）libc ++ abi.dylib：终止于   NSException类型的未捕获异常

我认为问题出现在 segue 代码中，而不是选择准确的ChannelObject或Object.livestream

这是我的第二个viewController的代码。其中包含第二个json文件。所以如果可能请更正此代码。

#import "Second.h"
#import "Channel.h"
#import "UIImageView+AFNetworking.h"
#import "Type.h"
#define getDataUrl @"https://creativestudy.000webhostapp.com/webservices/test.json"

@interface Second ()

@end

@implementation Second
@synthesize tvArray,currentObject;

- (void)viewDidLoad {
    [super viewDidLoad];

    [self retrieveData];



    // 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.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {

    return 1;
}

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

    return tvArray.count;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cells" forIndexPath:indexPath];

    Channel * ChannelObject;
    ChannelObject = [tvArray objectAtIndex:indexPath.row];

    cell.textLabel.text = ChannelObject.channelTitle;
    cell.detailTextLabel.text = ChannelObject.channelLivestream;
     cell.detailTextLabel.hidden = YES;
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;

    NSURL *url = [NSURL URLWithString:ChannelObject.channelImage];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    UIImage *placeholderImage = [UIImage imageNamed:@"placeholder"];
    __weak UITableViewCell *weakCell = cell;
    [cell.imageView setImageWithURLRequest:request placeholderImage:placeholderImage success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
        weakCell.imageView.image = image;
        [weakCell setNeedsLayout];
    } failure:nil];



    // Configure the cell...

    return cell;
}
-(void) getType:(id)typeObject{

    currentObject = typeObject;

}

/*
// 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;
}
*/


// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
        if ([segue.identifier isEqualToString:@"playVideo"]) {

            AVPlayerViewController *playerViewController = [segue destinationViewController];

             NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
             Channel * ChannelObject;
            ChannelObject = [self.tvArray objectAtIndex:(int)indexPath];
             NSURL *liveUrl = [NSURL URLWithString:ChannelObject.channelLivestream];
             playerViewController.player = [AVPlayer playerWithURL:liveUrl];
        [playerViewController.player play];

             }

}


-(void) retrieveData{
    NSURL * url = [NSURL URLWithString:getDataUrl];
    NSData * data = [NSData dataWithContentsOfURL:url];
    NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];

    tvArray = [[NSMutableArray alloc] init];

    for (int i = 0; i < jsonArray.count; i ++)
    {
        NSDictionary *aCategoryJSON = [jsonArray objectAtIndex:i];
        NSString *cId = [aCategoryJSON objectForKey:@"id"];
        NSString *cTitle = [aCategoryJSON objectForKey:@"title"];
        NSString *cCategory = [aCategoryJSON objectForKey:@"category_name"];
        NSString *cImage = [aCategoryJSON objectForKey:@"image"];
        NSString *cLivestream = [aCategoryJSON objectForKey:@"livestream"];
        NSString *cWebsite = [aCategoryJSON objectForKey:@"Website"];
        if (cCategory == currentObject.typeName){
        [tvArray addObject:[[Channel alloc] initWithChannelId:cId andChannelTitle:cTitle andChannelCategory:cCategory andChannelImage:cImage andChannelLivestream:cLivestream andChannelWebsite:cWebsite]];
        }
        else if ([currentObject.typeName isEqualToString: @"All"]){
        [tvArray addObject:[[Channel alloc] initWithChannelId:cId andChannelTitle:cTitle andChannelCategory:cCategory andChannelImage:cImage andChannelLivestream:cLivestream andChannelWebsite:cWebsite]];
        }

    }
    [self.tableView reloadData];
}

@end

Answer 1

你的问题在这里：

 ChannelObject = [self.tvArray objectAtIndex:(int)indexPath];

你已经将一个对象（一个NSIndexPath的实例）转换为一个int，而Objective-C已经让你了，因为它基于C，即使这没有意义。

indexPath是指向内存中对象的指针，因此当您将其转换为int时，会得到一个解释为整数的内存地址，这就是为什么您会看到尝试访问元素2097174的原因你的阵列。据推测，您已将转换添加到int，因为编译器告诉您不能在该函数中使用indexPath。

您需要做的是使用indexPath.row从NSIndexPath实例获取行整数。您还可以使用更现代的数组访问语法和小写字母来启动变量（大写字母用于类）：

Channel *channelObject = self.tvArray[indexPath.row];

如何在prepareForSegue方法

1 个答案: