如何添加“加载更多”选项到表格视图
我的应用程序有一个由Sqlite DB填充的表包含大量数据所以它会导致表视图中的延迟加载
这是代码
- (void) searchData {
//i=0;
[newSearchBar setShowsCancelButton:YES animated:YES];
NSLog(@"search data started ");
NSLog(@" checking value %@",newSearchBar.text);
NSString *databaseName = @"imeating.sql";
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
NSString *documentsDir=[documentPaths objectAtIndex:0];
NSString *databasePath=[documentsDir stringByAppendingPathComponent:databaseName];
sqlite3 *database;
if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK)
{
NSLog(@"with in if sqlite3 open");
// Setup the SQL Statement and compile it for faster access
sqlite3_stmt *compiledStatement ;
const char *sqlStatement ;
/* if ([searchFlag isEqualToString:@"DEF"])
{
sqlStatement = "select subitem_name, subitem_detail_id from subitem_detail limit 200" ;
}
else
{*/
sqlStatement = "select category_id, upper(subitem_name), subitem_detail_id, protein, carbohydrates, fat, calorie from subitem_detail where subitem_name LIKE ? order by subitem_name limit ?,?" ;
NSLog(@"inside search b4 wildsearch %@",searchString);
wildSearch = [NSString stringWithFormat:@"%@%@",searchString, @"%"];
NSLog(@"wildsearch %@",wildSearch);
[newSearchBar setShowsCancelButton:YES animated:YES];
//NSLog(@"inside search : %@", wildSearch);
//}
if (sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK)
{
NSLog(@"with in if sqlite3 prepare v2");
// if (![searchFlag isEqualToString:@"DEF"])
// {
sqlite3_bind_text(compiledStatement, 1, [wildSearch UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_int(compiledStatement, 2, llimit);
sqlite3_bind_int(compiledStatement, 3, ulimit);
// }
// Loop through the results and add it to array
if (llimit <200){
NSLog(@"with in if limit < 200");
itemArray = [[NSMutableArray alloc] init] ;
}
while (sqlite3_step(compiledStatement) == SQLITE_ROW) {
//NSLog(@" while sqlite3 step");
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init] ;
//[itemDic release];
//itemDic = nil ;
itemDic = [[[NSMutableDictionary alloc] init] autorelease];
NSString *categoryId = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)];
NSString *itemName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 1)];
NSString *itemId = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)];
NSString *protein = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 3)];
NSString *carbo = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 4)];
NSString *fat = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 5)];
NSString *calorie = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 6)];
/* NSLog(@"itemname : %@", itemName);
NSLog(@"itemid : %@", itemId);
NSLog(@"n");*/
[itemDic setObject:categoryId forKey:@"categoryId"];
[itemDic setObject:itemId forKey:@"itemId"];
[itemDic setObject:itemName forKey:@"itemName"];
[itemDic setObject:protein forKey:@"protein"];
[itemDic setObject:carbo forKey:@"carbohydrate"];
[itemDic setObject:fat forKey:@"fat"];
[itemDic setObject:calorie forKey:@"calorie"];
[itemArray addObject:itemDic];
if (ulimit%200 == 0)
{
//activity = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActionSheetStyleDefault];
//[activity startAnimating];
[newTableView reloadData];
//[newSearchBar setShowsCancelButton:YES animated:YES];
//NSLog(@"list all views after 1st reload: %@", [self.navigationController.viewControllers description]);
//[newTableView addSubview:activity];
//[activity stopAnimating];
//[activity release];
//NSLog(@" with in if");
}
[pool drain];
} /*else
{
UIAlertView *alert = [[UIAlertView alloc ] initWithTitle:@"Error" message:@"sqlite rows not returned" delegate:self cancelButtonTitle:@"OK" otherButtonTitles: nil] ;
[alert show];
}*/
}
} else
{
UIAlertView *alert = [[UIAlertView alloc ] initWithTitle:@"Error" message:@"DataBase Path doesn't exists" delegate:self cancelButtonTitle:@"OK" otherButtonTitles: nil] ;
[alert show];
}
//NSLog(@"itemArray desc : %@",[itemArray description]);
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
//NSLog(@"Inside number of sections in tableview");
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [itemArray 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];
}
//NSLog(@"indexpath row val : %d", indexPath.row);
tableIndex = indexPath ;
//NSLog(@"print indexpath row : %d", indexPath.row);
//NSLog(@"print limit : %d", limit);
if (indexPath.row > limit)
{
llimit = llimit+200 ;
ulimit = ulimit+200 ;
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
//[opq cancelAllOperations];
NSLog(@"before ns operation");
opq = [NSOperationQueue new];
//opq = [[NSOperationQueue alloc] init];
//[opq setMaxConcurrentOperationCount:2];
// [self performSelectorOnMainThread:@selector(searchData) withObject:nil waitUntilDone:YES];
NSInvocationOperation *op = [[[NSInvocationOperation alloc] initWithTarget:self selector:@selector(searchData) object:nil] autorelease];
[opq addOperation:op];
NSLog(@"after ns operation");
//[op release];
//[opq release];
[pool drain];
i++;
limit = limit + 120 ;
NSLog(@"i=%d",i);
//[cell setText:[[itemArray objectAtIndex:indexPath.row] valueForKey:@"itemName"]];
}
// Configure the cell.
//[cell setText:[[itemArray objectAtIndex:indexPath.row] valueForKey:@"itemName"]];
cell.textLabel.text = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"itemName"] ;
NSString *pval, *cval, *fval, *cal ;
if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"protein"] length] <= 5)
pval = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"protein"];
else
pval = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"protein"] substringWithRange:NSMakeRange(0, 5)];
if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"carbohydrate"] length] <= 5)
cval = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"carbohydrate"];
else
cval = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"carbohydrate"] substringWithRange:NSMakeRange(0, 5)];
if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"fat"] length] <= 5)
fval = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"fat"];
else
fval = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"fat"] substringWithRange:NSMakeRange(0, 5)];
if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"calorie"] length] <= 5)
cal = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"calorie"];
else
cal = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"calorie"] substringWithRange:NSMakeRange(0, 5)];
cell.detailTextLabel.text =
[NSString stringWithFormat:@"Prot: %@ Carb: %@ Fat: %@ Cal: %@", pval, cval, fval, cal] ;
return cell;
}
我需要在我的表视图的行中加载“更多”按钮，以便在特定的时间段内从sqlite数据库加载记录
在部分的行数中添加+ 1：
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [itemArray count] + 1;
}
然后在cellforrowatindexpath中查看indexPath.row是否大于[itemArray count]。 如果是，则将文本“加载更多...”作为单元格的标题。
在didSelectRowAtIndexPath中，查看indexPath.row是否等于[itemArray count]。 如果是这种情况，那么向itemArray添加更多的结果，然后调用[tableView reloadData]。
对于某些UI改进，您可以在表视图顶部添加一个UIActivityIndicator，以显示某些处理正在后台进行。