Question

我使用AFNetworking在youtube视频中填充UITableView。 YouTube API仅允许每个请求获得最多50个结果。因此，我必须使用多个网址才能获得超过50个结果。

我创建了一个方法，它将对给定的URL执行AFNetworkings AFJSONRequestOperation。

我认为在收到JSON数据之前就已经创建了UITable。在创建Method之前，一切都运行良好。

这是我第一次创建方法。在过去的几天里，我一直试图在UITable上加载超过50个YouTube视频。请看一下我的代码。

这是我的代码，您也可以从

下载整个项目

QQViewController.m

-(void)viewWillAppear:(BOOL)animated {

    [super viewWillAppear:animated];
    //[super viewDidLoad];

    NSString *urlAsString = @"http://gdata.youtube.com/feeds/api/playlists/PL7CF5B0AC3B1EB1D5?v=2&alt=jsonc&max-results=50";


    // I am not sure how i am supposed to populate the uitableview with the second link :(

     NSString *urlAsString2 = @"http://gdata.youtube.com/feeds/api/playlists/PL7CF5B0AC3B1EB1D5?v=2&alt=jsonc&max-results=50&start-index=51";



    self.myurl = [NSURL URLWithString:urlAsString];

    [self getJSONfromURL:self.myurl];

[self.tableView reloadData];

}

-(void)viewDidAppear:(BOOL)animated {

        [super viewDidAppear:animated]; 

        self.videoMetaData = [self.myJSON valueForKeyPath:@"items.video"];

        NSLog(@" QQVC video Meta Data %@", self.videoMetaData);


        self.allThumbnails = [self.myJSON valueForKeyPath:@"data.items.video.thumbnail"];


        // The table need to be reloaded or else we will get an empty table.

        [self.tableView reloadData]; // Must Reload

        // NSLog(@" video Meta Data %@", self.videoMetaData);


}

//这是方法

-(void)getJSONfromURL:(NSURL *)url {

    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    // setup AFNetworking stuff
    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        // call delegate or processing method on success

       // [self.myJSON = (NSArray *)JSON];

        self.myJSON = [JSON valueForKey:@"data"];
        [self.tableView reloadData];
       //NSLog(@" in get JSon method %@", self.myJSON);

    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
        NSLog(@"Request Failed with Error: %@, %@", error, error.userInfo);
    }];


    [operation start];



}

- (void)viewDidLoad
{
    [super viewDidLoad];
}

Answer 1

getJSONfromURL：方法中存在几个问题。主要问题是你将self.myJSON定义为[JSON valueForKey：@“data”]，然后将self.allThumbnails定义为[self.myJSON valueForKeyPath：@“data.items.video.thumbnail”] - 你用过的再次“数据”，所以self.thumbnails是null。这似乎工作正常：

-(void)getJSONfromURL:(NSURL *)url {
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    // setup AFNetworking stuff
    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        self.myJSON = [JSON valueForKey:@"data"];
        self.allThumbnails = [self.myJSON valueForKeyPath:@"items.video.thumbnail"];
        self.videoMetaData = [self.myJSON valueForKeyPath:@"items.video"];
        [self.tableView reloadData];

    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
        NSLog(@"Request Failed with Error: %@, %@", error, error.userInfo);
    }];

    [operation start];
}

如果您想从多个网址加载日期，可以这样做。我添加了一个计数器来跟踪URL字符串数组的进度。每次下载后都会重新加载该表，因此在显示某些数据之前，不必等待整个事情完成。

@interface QWViewController ()
@property (strong,nonatomic) NSArray *urlStrings;
@end

@implementation QWViewController {
    int counter;
}


-(void)viewDidLoad {
    [super viewDidLoad];
    counter = 0;
    NSString *urlAsString = @"http://gdata.youtube.com/feeds/api/playlists/PL7CF5B0AC3B1EB1D5?v=2&alt=jsonc&max-results=50";
    NSString *urlAsString2 = @"http://gdata.youtube.com/feeds/api/playlists/PL7CF5B0AC3B1EB1D5?v=2&alt=jsonc&max-results=50&start-index=51";
    self.urlStrings = @[urlAsString,urlAsString2];
    self.allThumbnails = [NSMutableArray array];
    self.videoMetaData = [NSMutableArray array];
    [self getJSONFromURL:self.urlStrings[0]];
}


-(void)getJSONFromURL:(NSString *) urlString {
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        self.myJSON = [JSON valueForKey:@"data"];
        [self.allThumbnails addObjectsFromArray:[self.myJSON valueForKeyPath:@"items.video.thumbnail"]];
        [self.videoMetaData  addObjectsFromArray:[self.myJSON valueForKeyPath:@"items.video"]];
        [self.tableView reloadData];
        counter += 1;
        if (counter < self.urlStrings.count) [self getJSONFromURL:self.urlStrings[counter]];
    }

    failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
    NSLog(@"Request Failed with Error: %@, %@", error, error.userInfo);
    }];
    [operation start];
}

Answer 2

将重新加载的tableview调用移至此处。

-(void)getJSONfromURL:(NSURL *)url {

    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    // setup AFNetworking stuff
    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        // call delegate or processing method on success

       // [self.myJSON = (NSArray *)JSON];

        self.myJSON = [JSON valueForKey:@"data"];
        [self.tableView reloadData];
       //NSLog(@" in get JSon method %@", self.myJSON);

    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
        NSLog(@"Request Failed with Error: %@, %@", error, error.userInfo);
    }];


    [operation start];



}

将数据从一种方法传递到另一种方法

2 个答案: