Xcode Table 查看数据在我拉动刷新时重复
Xcode Table view Data is getting duplicated when I pull to refresh
嗨，每次我使用下拉刷新时，我的数据都会重复。例如。 table 视图中的 5 个初始条目在一次拉动刷新时翻倍为 10 个，并在随后的拉动刷新中再添加 5 个。我怎样才能停止重复..我想确保只下载新项目并且 table 中的现有数据不会再次下载。
@implementation RootViewController
@synthesize allEntries = _allEntries;
@synthesize feeds = _feeds;
@synthesize queue = _queue;
@synthesize webViewController = _webViewController;
#pragma mark -
#pragma mark View lifecycle
- (void)addRows {
RSSEntry *entry1 = [[[RSSEntry alloc] initWithBlogTitle:@"1"
articleTitle:@"1"
articleUrl:@"1"
articleDate:[NSDate date]] autorelease];
RSSEntry *entry2 = [[[RSSEntry alloc] initWithBlogTitle:@"2"
articleTitle:@"2"
articleUrl:@"2"
articleDate:[NSDate date]] autorelease];
RSSEntry *entry3 = [[[RSSEntry alloc] initWithBlogTitle:@"3"
articleTitle:@"3"
articleUrl:@"3"
articleDate:[NSDate date]] autorelease];
[_allEntries insertObject:entry1 atIndex:0];
[_allEntries insertObject:entry2 atIndex:0];
[_allEntries insertObject:entry3 atIndex:0];
}
- (void)viewDidLoad {
[super viewDidLoad];
self.title = @"Songs";
self.allEntries = [NSMutableArray array];
self.queue = [[[NSOperationQueue alloc] init] autorelease];
self.feeds = [NSArray arrayWithObjects:
@"http://hindisongs.bestofindia.co/?feed=rss2",
nil];
self.refreshControl = [UIRefreshControl new];
self.refreshControl.attributedTitle = [[NSAttributedString alloc] initWithString:@"Pull to refresh"];
[self.refreshControl addTarget:self action:@selector(bindDatas) forControlEvents:UIControlEventValueChanged];
[self bindDatas]; //called at the first time
}
-(void)bindDatas
{
//GET YOUR DATAS HERE…
for (NSString *feed in _feeds) {
NSURL *url = [NSURL URLWithString:feed];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[_queue addOperation:request];
}
//update the tableView
[self.tableView reloadData];
if(self.refreshControl != nil && self.refreshControl.isRefreshing == TRUE)
{
[self.refreshControl endRefreshing];
}
}
- (void)parseRss:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
NSArray *channels = [rootElement elementsForName:@"channel"];
for (GDataXMLElement *channel in channels) {
NSString *blogTitle = [channel valueForChild:@"title"];
NSArray *items = [channel elementsForName:@"item"];
for (GDataXMLElement *item in items) {
NSString *articleTitle = [item valueForChild:@"title"];
NSString *articleUrl = [item valueForChild:@"link"];
NSString *articleDateString = [item valueForChild:@"pubDate"];
NSDate *articleDate = [NSDate dateFromInternetDateTimeString:articleDateString formatHint:DateFormatHintRFC822];
RSSEntry *entry = [[[RSSEntry alloc] initWithBlogTitle:blogTitle
articleTitle:articleTitle
articleUrl:articleUrl
articleDate:articleDate] autorelease];
[entries addObject:entry];
}
}
}
- (void)parseAtom:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
NSString *blogTitle = [rootElement valueForChild:@"title"];
NSArray *items = [rootElement elementsForName:@"entry"];
for (GDataXMLElement *item in items) {
NSString *articleTitle = [item valueForChild:@"title"];
NSString *articleUrl = nil;
NSArray *links = [item elementsForName:@"link"];
for(GDataXMLElement *link in links) {
NSString *rel = [[link attributeForName:@"rel"] stringValue];
NSString *type = [[link attributeForName:@"type"] stringValue];
if ([rel compare:@"alternate"] == NSOrderedSame &&
[type compare:@"text/html"] == NSOrderedSame) {
articleUrl = [[link attributeForName:@"href"] stringValue];
}
}
NSString *articleDateString = [item valueForChild:@"updated"];
NSDate *articleDate = [NSDate dateFromInternetDateTimeString:articleDateString formatHint:DateFormatHintRFC3339];
RSSEntry *entry = [[[RSSEntry alloc] initWithBlogTitle:blogTitle
articleTitle:articleTitle
articleUrl:articleUrl
articleDate:articleDate] autorelease];
[entries addObject:entry];
}
}
- (void)parseFeed:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
if ([rootElement.name compare:@"rss"] == NSOrderedSame) {
[self parseRss:rootElement entries:entries];
} else if ([rootElement.name compare:@"feed"] == NSOrderedSame) {
[self parseAtom:rootElement entries:entries];
} else {
NSLog(@"Unsupported root element: %@", rootElement.name);
}
}
- (void)requestFinished:(ASIHTTPRequest *)request {
[_queue addOperationWithBlock:^{
NSError *error;
GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:[request responseData]
options:0 error:&error];
if (doc == nil) {
NSLog(@"Failed to parse %@", request.url);
} else {
NSMutableArray *entries = [NSMutableArray array];
[self parseFeed:doc.rootElement entries:entries];
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
for (RSSEntry *entry in entries) {
int insertIdx = [_allEntries indexForInsertingObject:entry sortedUsingBlock:^(id a, id b) {
RSSEntry *entry1 = (RSSEntry *) a;
RSSEntry *entry2 = (RSSEntry *) b;
return [entry1.articleDate compare:entry2.articleDate];
}];
[_allEntries insertObject:entry atIndex:insertIdx];
[self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:insertIdx inSection:0]]
withRowAnimation:UITableViewRowAnimationRight];
}
}];
}
}];
}
- (void)requestFailed:(ASIHTTPRequest *)request {
NSError *error = [request error];
NSLog(@"Error: %@", error);
}
/*
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
}
*/
/*
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
}
*/
/*
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
}
*/
/*
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
}
*/
/*
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations.
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
*/
#pragma mark -
#pragma mark Table view data source
// Customize the number of sections in the table view.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [_allEntries count];
}
// Customize the appearance of table view cells.
- (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] autorelease];
}
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
NSDateFormatter * dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setTimeStyle:NSDateFormatterMediumStyle];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
NSString *articleDateString = [dateFormatter stringFromDate:entry.articleDate];
cell.textLabel.text = entry.articleTitle;
cell.detailTextLabel.text = [NSString stringWithFormat:@"%@ - %@", articleDateString, entry.blogTitle];
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:[NSArray arrayWithObject: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 -
#pragma mark Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
if (_webViewController == nil) {
self.webViewController = [[[WebViewController alloc] initWithNibName:@"WebViewController" bundle:[NSBundle mainBundle]] autorelease];
}
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
_webViewController.entry = entry;
[self.navigationController pushViewController:_webViewController animated:YES];
}
#pragma mark -
#pragma mark Memory management
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Relinquish ownership any cached data, images, etc that aren't in use.
self.webViewController = nil;
}
- (void)viewDidUnload {
// Relinquish ownership of anything that can be recreated in viewDidLoad or on demand.
// For example: self.myOutlet = nil;
}
- (void)dealloc {
[_allEntries release];
_allEntries = nil;
[_queue release];
_queue = nil;
[_feeds release];
_feeds = nil;
[_webViewController release];
_webViewController = nil;
[super dealloc];
}
问题是您一直将对象插入到 _allEntries 而没有重置它。您会希望在某个时候清空它，无论是当用户拉动刷新时，还是在您向其中添加任何新对象之前收到新数据时。
[_allEntries removeAllObjects];
尝试将其放在 bindDatas 的开头。
嗨，每次我使用下拉刷新时，我的数据都会重复。例如。 table 视图中的 5 个初始条目在一次拉动刷新时翻倍为 10 个，并在随后的拉动刷新中再添加 5 个。我怎样才能停止重复..我想确保只下载新项目并且 table 中的现有数据不会再次下载。
@implementation RootViewController
@synthesize allEntries = _allEntries;
@synthesize feeds = _feeds;
@synthesize queue = _queue;
@synthesize webViewController = _webViewController;
#pragma mark -
#pragma mark View lifecycle
- (void)addRows {
RSSEntry *entry1 = [[[RSSEntry alloc] initWithBlogTitle:@"1"
articleTitle:@"1"
articleUrl:@"1"
articleDate:[NSDate date]] autorelease];
RSSEntry *entry2 = [[[RSSEntry alloc] initWithBlogTitle:@"2"
articleTitle:@"2"
articleUrl:@"2"
articleDate:[NSDate date]] autorelease];
RSSEntry *entry3 = [[[RSSEntry alloc] initWithBlogTitle:@"3"
articleTitle:@"3"
articleUrl:@"3"
articleDate:[NSDate date]] autorelease];
[_allEntries insertObject:entry1 atIndex:0];
[_allEntries insertObject:entry2 atIndex:0];
[_allEntries insertObject:entry3 atIndex:0];
}
- (void)viewDidLoad {
[super viewDidLoad];
self.title = @"Songs";
self.allEntries = [NSMutableArray array];
self.queue = [[[NSOperationQueue alloc] init] autorelease];
self.feeds = [NSArray arrayWithObjects:
@"http://hindisongs.bestofindia.co/?feed=rss2",
nil];
self.refreshControl = [UIRefreshControl new];
self.refreshControl.attributedTitle = [[NSAttributedString alloc] initWithString:@"Pull to refresh"];
[self.refreshControl addTarget:self action:@selector(bindDatas) forControlEvents:UIControlEventValueChanged];
[self bindDatas]; //called at the first time
}
-(void)bindDatas
{
//GET YOUR DATAS HERE…
for (NSString *feed in _feeds) {
NSURL *url = [NSURL URLWithString:feed];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[_queue addOperation:request];
}
//update the tableView
[self.tableView reloadData];
if(self.refreshControl != nil && self.refreshControl.isRefreshing == TRUE)
{
[self.refreshControl endRefreshing];
}
}
- (void)parseRss:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
NSArray *channels = [rootElement elementsForName:@"channel"];
for (GDataXMLElement *channel in channels) {
NSString *blogTitle = [channel valueForChild:@"title"];
NSArray *items = [channel elementsForName:@"item"];
for (GDataXMLElement *item in items) {
NSString *articleTitle = [item valueForChild:@"title"];
NSString *articleUrl = [item valueForChild:@"link"];
NSString *articleDateString = [item valueForChild:@"pubDate"];
NSDate *articleDate = [NSDate dateFromInternetDateTimeString:articleDateString formatHint:DateFormatHintRFC822];
RSSEntry *entry = [[[RSSEntry alloc] initWithBlogTitle:blogTitle
articleTitle:articleTitle
articleUrl:articleUrl
articleDate:articleDate] autorelease];
[entries addObject:entry];
}
}
}
- (void)parseAtom:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
NSString *blogTitle = [rootElement valueForChild:@"title"];
NSArray *items = [rootElement elementsForName:@"entry"];
for (GDataXMLElement *item in items) {
NSString *articleTitle = [item valueForChild:@"title"];
NSString *articleUrl = nil;
NSArray *links = [item elementsForName:@"link"];
for(GDataXMLElement *link in links) {
NSString *rel = [[link attributeForName:@"rel"] stringValue];
NSString *type = [[link attributeForName:@"type"] stringValue];
if ([rel compare:@"alternate"] == NSOrderedSame &&
[type compare:@"text/html"] == NSOrderedSame) {
articleUrl = [[link attributeForName:@"href"] stringValue];
}
}
NSString *articleDateString = [item valueForChild:@"updated"];
NSDate *articleDate = [NSDate dateFromInternetDateTimeString:articleDateString formatHint:DateFormatHintRFC3339];
RSSEntry *entry = [[[RSSEntry alloc] initWithBlogTitle:blogTitle
articleTitle:articleTitle
articleUrl:articleUrl
articleDate:articleDate] autorelease];
[entries addObject:entry];
}
}
- (void)parseFeed:(GDataXMLElement *)rootElement entries:(NSMutableArray *)entries {
if ([rootElement.name compare:@"rss"] == NSOrderedSame) {
[self parseRss:rootElement entries:entries];
} else if ([rootElement.name compare:@"feed"] == NSOrderedSame) {
[self parseAtom:rootElement entries:entries];
} else {
NSLog(@"Unsupported root element: %@", rootElement.name);
}
}
- (void)requestFinished:(ASIHTTPRequest *)request {
[_queue addOperationWithBlock:^{
NSError *error;
GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:[request responseData]
options:0 error:&error];
if (doc == nil) {
NSLog(@"Failed to parse %@", request.url);
} else {
NSMutableArray *entries = [NSMutableArray array];
[self parseFeed:doc.rootElement entries:entries];
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
for (RSSEntry *entry in entries) {
int insertIdx = [_allEntries indexForInsertingObject:entry sortedUsingBlock:^(id a, id b) {
RSSEntry *entry1 = (RSSEntry *) a;
RSSEntry *entry2 = (RSSEntry *) b;
return [entry1.articleDate compare:entry2.articleDate];
}];
[_allEntries insertObject:entry atIndex:insertIdx];
[self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:insertIdx inSection:0]]
withRowAnimation:UITableViewRowAnimationRight];
}
}];
}
}];
}
- (void)requestFailed:(ASIHTTPRequest *)request {
NSError *error = [request error];
NSLog(@"Error: %@", error);
}
/*
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
}
*/
/*
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
}
*/
/*
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
}
*/
/*
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
}
*/
/*
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations.
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
*/
#pragma mark -
#pragma mark Table view data source
// Customize the number of sections in the table view.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [_allEntries count];
}
// Customize the appearance of table view cells.
- (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] autorelease];
}
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
NSDateFormatter * dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setTimeStyle:NSDateFormatterMediumStyle];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
NSString *articleDateString = [dateFormatter stringFromDate:entry.articleDate];
cell.textLabel.text = entry.articleTitle;
cell.detailTextLabel.text = [NSString stringWithFormat:@"%@ - %@", articleDateString, entry.blogTitle];
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:[NSArray arrayWithObject: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 -
#pragma mark Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
if (_webViewController == nil) {
self.webViewController = [[[WebViewController alloc] initWithNibName:@"WebViewController" bundle:[NSBundle mainBundle]] autorelease];
}
RSSEntry *entry = [_allEntries objectAtIndex:indexPath.row];
_webViewController.entry = entry;
[self.navigationController pushViewController:_webViewController animated:YES];
}
#pragma mark -
#pragma mark Memory management
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Relinquish ownership any cached data, images, etc that aren't in use.
self.webViewController = nil;
}
- (void)viewDidUnload {
// Relinquish ownership of anything that can be recreated in viewDidLoad or on demand.
// For example: self.myOutlet = nil;
}
- (void)dealloc {
[_allEntries release];
_allEntries = nil;
[_queue release];
_queue = nil;
[_feeds release];
_feeds = nil;
[_webViewController release];
_webViewController = nil;
[super dealloc];
}
问题是您一直将对象插入到 _allEntries 而没有重置它。您会希望在某个时候清空它，无论是当用户拉动刷新时，还是在您向其中添加任何新对象之前收到新数据时。
[_allEntries removeAllObjects];
尝试将其放在 bindDatas 的开头。