总和从coreData和显示检索值

问题描述：

我想要添加给定部分中的所有金额标签，并显示在部分标题中的总和。我的表格视图看起来像这样。总和从coreData和显示检索值

段头 - 12/07/2012

categoryName Amount 
Groceries  100 
    Social  100

段头 - 10/04/2012

categoryName Amount 
    Gas   500 
    Social  600

现在我想在第一部分1100 header.and显示总200在接下来的头

-(IBAction)bydate:(id)sender 
{ 
[self.expenseArray removeAllObjects]; 
[self.expenseArrayCount removeAllObjects]; 

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init]; 
[dateFormatter setDateStyle:NSDateFormatterMediumStyle]; 

for(NSManagedObject *records in self.listOfExpenses){ 
    NSString *compareDates = [dateFormatter stringFromDate:[records valueForKey:@"date"]]; 
    BOOL isAvail = NO; 
    for (int i = 0; i<[self.expenseArray count]; i++){ 
     if([compareDates isEqualToString:[self.expenseArray objectAtIndex:i]]) 
      isAvail = YES; 
    } 
    if(!isAvail) 
     [self.expenseArray addObject:compareDates]; 
} 
int count = 0; 
for (int i = 0 ; i < [self.expenseArray count] ; i ++){ 
    NSString *compareDates = [self.expenseArray objectAtIndex:i]; 
    for(NSManagedObject *info in self.listOfExpenses){ 
     if([compareDates isEqualToString:[dateFormatter stringFromDate:[info valueForKey:@"date"]]]) 
      count++; 
    } 
    [self.expenseArrayCount addObject:[NSNumber numberWithInt:count]]; 
    count = 0; 
} 
[self.byDateTab reloadData]; 
[dateFormatter release]; 
} 

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    //not posting un necessary code. 

    else if (tableView == self.byDateTab) 
{ 
    for(int i = 0; i < [self.expenseArrayCount count];i++) 
    { 
     if(indexPath.section == 0) 
     { 
      NSManagedObject *records = nil; 
      records = [self.listOfExpenses objectAtIndex:indexPath.row]; 
      self.firstLabel.text = [records valueForKey:@"category"]; 
      self.secondLabel.text = [records valueForKey:@"details"]; 
      NSString *amountString = [NSString stringWithFormat:@"%@",[records valueForKey:@"amount"]]; 
      self.thirdLabel.text = amountString; 
     } 
     else if (indexPath.section == i) 
     { 
      int rowCount = 0; 
      for(int j=0; j<indexPath.section; j++) 
      { 
       rowCount = rowCount + [[self.expenseArrayCount objectAtIndex:j]intValue]; 
      } 
      NSManagedObject *records = nil; 
      records = [self.listOfExpenses objectAtIndex:(indexPath.row + rowCount) ]; 
      self.firstLabel.text = [records valueForKey:@"category"]; 
      self.secondLabel.text = [records valueForKey:@"details"]; 
      NSString *amountString = [NSString stringWithFormat:@"%@",[records valueForKey:@"amount"]]; 
      self.thirdLabel.text = amountString; 

     } 
    } 
} 


-(NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section 
{ 
NSString *title = [[[NSString alloc]init]autorelease]; 
if(tableView == self.byDateTab) 
    title = [self.expenseArray objectAtIndex:section]; 
return title; 
} 

-(UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section 
{ 
UIView *headerView = [[[UIView alloc]init] autorelease]; 
if(tableView == self.byDateTab){ 
    headerView.frame = CGRectMake(310, 0, tableView.bounds.size.width, 30); 
    [headerView setBackgroundColor:[UIColor colorWithRed:149.0/255 green:163.0/255 blue:173.0/255 alpha:1]]; 
    UILabel *leftLabel = [[[UILabel alloc]initWithFrame:CGRectMake(10, 3, tableView.bounds.size.width-10, 18)]autorelease]; 
    leftLabel.text = [self tableView:tableView titleForHeaderInSection:section]; 
    leftLabel.textColor = [UIColor whiteColor]; 
    leftLabel.font = [UIFont fontWithName:@"AmericanTypewriter" size:17.0]; 
    leftLabel.backgroundColor = [UIColor clearColor]; 
    [headerView addSubview:leftLabel]; 

    NSNumberFormatter *formatter = [[NSNumberFormatter alloc]init]; 
    NSString *a = [formatter currencySymbol]; 

    UILabel *rightLabel = [[[UILabel alloc]initWithFrame:CGRectMake(250, 3, tableView.bounds.size.width-10, 18)]autorelease]; 
    rightLabel.text = [NSString stringWithFormat:@"(%@)",a]; 
    rightLabel.textColor = [UIColor whiteColor]; 
    rightLabel.font = [UIFont fontWithName:@"AmericanTypewriter" size:17.0]; 
    rightLabel.backgroundColor = [UIColor clearColor]; 
    [headerView addSubview:rightLabel]; 



}

您应该尝试编写迭代某个节的记录并返回总金额的方法。你的代码不容易理解。我不明白'tableView：cellForRowAtIndexPath：'内循环的目的。 – florian 2012-07-27 11:35:34

答

你需要实现这个方法：
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
它返回给定部分的标题。因此，您需要确定哪些记录与节号相匹配，并迭代记录以计算总金额。
您可能需要考虑从上述方法中完成此操作，以便每次调用此方法时不计算每个部分的总金额。
为您加载数据，只有做到这一点，您可以立即建立的“预先计算”称号的数组：

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section 
{ 
    return [titles objectAtIndex:section]; 
}

你能编辑你的问题并提供这种方法的代码？ – florian 2012-07-27 09:42:48

更新了代码..！ – 2012-07-27 09:52:41

答

的逻辑很简单。我真的不想深入到你的代码，所以这一块会给你你需要一个解释

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section { 
    NSArray *sectionArray = [mySectionsDictionary objectForKey:[NSString stringWithFormat:@"%d", section]]; 
    int total = 0; 
    for (MyCustomCoreDataObject *object in sectionArray) { 
    total += object.amount.intValue; 
    } 
    return [NSString stringWithFormat:@"%d", total]; 
}

我没有使用任何字典..我已更新我的代码..请检查 – 2012-07-27 10:05:57

答

注意（我看你不使用fetchResultController，我也用它作为推荐它将帮助你执行此任务和其他任务，并显示核心数据实体的表格视图）。

随着fetchResultController：

您应该添加totalAmount的NSString您获取实体类（您在fetchResultController获取实体）。

然后将添加操作添加到该类。在里面创建你的计算，所以你会得到一个字符串的总量。

-(NSString*)totalAmount{ 
    NSInteger amount = 0; 
    //do your calculation here 
    return [NSString stringWithFormat:@"amount = %i",amount]; 
}

，然后在结果取控制器通过totalAmount为您的板块名称关键路径，这将返回totalAmount串每个部分：

NSFetchedResultsController *fetchedResultsController = 
[[NSFetchedResultsController alloc] initWithFetchRequest:request 
            managedObjectContext:managedObjectContext 
             sectionNameKeyPath:@"totalAmount" cacheName:nil];

然后编辑您的节头方法，使表视图将正确地起作用：

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { 
    // Return the number of sections. 
    return ([[fetchedResultsController sections] count]); 
} 


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { 
    // Return the number of rows in the section. 
     id <NSFetchedResultsSectionInfo> sectionInfo = [[fetchedResultsController sections] objectAtIndex:section];

最后，设置量文本用于从所述取结果控制各部分：

- (NSString *)controller:(NSFetchedResultsController *)controller sectionIndexTitleForSectionName:(NSString *)sectionName { 
     return sectionName; 
}

总和从coreData和显示检索值

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