ios - 来自 channel rss feed 的 Youtube 缩略图？

Question

我正在尝试将 youtube channel 的提要加载到带有 rss 提要的 uitableview 中。我需要它来显示各个视频的缩略图。我只能使用不起作用的 gdata 客户端找到它。这是我到目前为止的代码:

视频.h:

#import <UIKit/UIKit.h>

@interface Videos : UITableViewController<NSXMLParserelegate>{
IBOutlet UITableView * newsTable;
UIActivityIndicatorView * activityIndicator;

CGSize cellSize;

NSXMLParser * rssParser;

NSMutableArray * stories;


// a temporary item; added to the "stories" array one at a time, and cleared for the     next one
NSMutableDictionary * item;

// it parses through the document, from top to bottom...
// we collect and cache each sub-element value, and then save each item to our array.
// we use these to track each current item, until it's ready to be added to the "stories" array
NSString * currentElement;
NSMutableString * currentTitle, * currentDate, * currentSummary, * currentLink;
}
- (void)parseXMLFileAtURL:(NSString *)URL;

@end

视频.m

#import "Videos.h"
#import "AppDelegate.h"


@implementation Videos

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
    // Custom initialization
    self.tabBarItem.image = [UIImage imageNamed:@"clapboard@2x.png"];

}
return self;
}



- (void)viewDidLoad {
// Add the following line if you want the list to be editable

}


- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [stories count];
}


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

static NSString *MyIdentifier = @"MyIdentifier";

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:MyIdentifier];

}

// Set up the cell
int storyIndex = [indexPath indexAtPosition: [indexPath length] - 1];
cell.textLabel.text=[[stories objectAtIndex: storyIndex] objectForKey: @"title"];

return cell;
}


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

int storyIndex = [indexPath indexAtPosition: [indexPath length] - 1];

NSString * storyLink = [[stories objectAtIndex: storyIndex] objectForKey: @"link"];
NSLog(@"%@",stories );
// clean up the link - get rid of spaces, returns, and tabs...
storyLink = [storyLink stringByReplacingOccurrencesOfString:@" " withString:@""];
storyLink = [storyLink stringByReplacingOccurrencesOfString:@"\n" withString:@""];
storyLink = [storyLink stringByReplacingOccurrencesOfString:@"  " withString:@""];

// open in Safari
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:storyLink]];
}


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

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

if ([stories count] == 0) {
    NSString * path =     @"https://youtube.com/rss/user/TheGruenebergBrother/videos.rss";

    [self parseXMLFileAtURL:path];
}

cellSize = CGSizeMake([newsTable bounds].size.width, 60);
}

- (void)viewWillDisappear:(BOOL)animated {
}

- (void)viewDidDisappear:(BOOL)animated {
}

#pragma mark - parseing_Delegate_methods
- (void)parserDidStartDocument:(NSXMLParser *)parser{
NSLog(@"found file and started parsing");

}

- (void)parseXMLFileAtURL:(NSString *)URL
{
stories = [[NSMutableArray alloc] init];

//you must then convert the path to a proper NSURL or it won't work
NSURL *xmlURL = [NSURL URLWithString:URL];

// here, for some reason you have to use NSClassFromString when trying to alloc   NSXMLParser, otherwise you will get an object not found error
// this may be necessary only for the toolchain
rssParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL];

// Set self as the delegate of the parser so that it will receive the parser delegate methods callbacks.
[rssParser setDelegate:self];

// Depending on the XML document you're parsing, you may want to enable these features of NSXMLParser.
[rssParser setShouldProcessNamespaces:NO];
[rssParser setShouldReportNamespacePrefixes:NO];
[rssParser setShouldResolveExternalEntities:NO];

[rssParser parse];

}




- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
NSString * errorString = [NSString stringWithFormat:@"Unable to download story feed   from web site (Error code %i )", [parseError code]];
NSLog(@"error parsing XML: %@", errorString);

UIAlertView * errorAlert = [[UIAlertView alloc] initWithTitle:@"Error loading content" message:errorString delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[errorAlert show];
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
//NSLog(@"found this element: %@", elementName);
currentElement = [elementName copy];
if ([elementName isEqualToString:@"item"]) {
    // clear out our story item caches...
    item = [[NSMutableDictionary alloc] init];
    currentTitle = [[NSMutableString alloc] init];
    currentDate = [[NSMutableString alloc] init];
    currentSummary = [[NSMutableString alloc] init];
    currentLink = [[NSMutableString alloc] init];
}

}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
//NSLog(@"ended element: %@", elementName);
if ([elementName isEqualToString:@"item"]) {
    // save values to an item, then store that item into the array...
    [item setObject:currentTitle forKey:@"title"];
    [item setObject:currentLink forKey:@"link"];
    [item setObject:currentSummary forKey:@"summary"];
    [item setObject:currentDate forKey:@"date"];

    [stories addObject:[item copy]];
    NSLog(@"adding story: %@", currentTitle);
}

}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
//NSLog(@"found characters: %@", string);
// save the characters for the current item...
if ([currentElement isEqualToString:@"title"]) {
    [currentTitle appendString:string];
} else if ([currentElement isEqualToString:@"link"]) {
    [currentLink appendString:string];
} else if ([currentElement isEqualToString:@"description"]) {
    [currentSummary appendString:string];
} else if ([currentElement isEqualToString:@"pubDate"]) {
    [currentDate appendString:string];
}

}

- (void)parserDidEndDocument:(NSXMLParser *)parser {

[activityIndicator stopAnimating];
[activityIndicator removeFromSuperview];

NSLog(@"all done!");
NSLog(@"stories array has %d items", [stories count]);
[newsTable reloadData];
}





- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}


- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview
// Release anything that's not essential, such as cached data
}


- (void)dealloc {

[currentElement release];
[rssParser release];
[stories release];
[item release];
[currentTitle release];
[currentDate release];
[currentSummary release];
[currentLink release];

[super dealloc];
}


@end

还有代码应该放哪里，代码是什么？谢谢

Answer 1

有一个缩略图 url，

http://img.youtube.com/vi/VIDEOIDHERE/0.jpg
http://img.youtube.com/vi/VIDEOIDHERE/1.jpg
http://img.youtube.com/vi/VIDEOIDHERE/2.jpg
http://img.youtube.com/vi/VIDEOIDHERE/3.jpg

将为您获取任何视频的缩略图。数字代表质量，零是最高的。例如:

http://img.youtube.com/vi/F2Jko4Ipdrs/0.jpg