iPhone:在分组的UITableview的每个部分中重复行 [英] iPhone: Repeating Rows in Each Section of Grouped UITableview
问题描述
我正在尝试学习如何将UITableView与SQLite后端结合使用.我的问题是我已经用数据库中的记录填充了表格，但是节标题却有问题.我无法为此找到合适的设置，我将在每个部分重复所有任务.
I'm trying to learn how to use the UITableView in conjunction with a SQLite back end. My issue is that I've gotten the table to populate with the records from the database, however I'm having a problem with the section titles. I am not able to figure out the proper set up for this, and I'm repeating all tasks under each section.
该表如下所示.组字段是我试图从中提取部分标题的地方.
The table looks like this. The groups field is where I'm trying to pull the section title from.
TaskID groups TaskName sched lastCompleted nextCompleted success
1 Household laundry 3 03/19/2010 03/22/2010 y
1 Automotive Change oil 3 03/20/2010 03/23/2010 y
在viewDidLoad方法中，我从下表中的每一列创建一个数组，如下所示.
In my viewDidLoad Method, I create an array from each column in the table like below.
//Create and initialize arrays from table columns
//______________________________________________________________________________________
ids =[[NSMutableArray alloc] init];
tasks =[[NSMutableArray alloc] init];
sched =[[NSMutableArray alloc] init];
lastComplete =[[NSMutableArray alloc] init];
nextComplete =[[NSMutableArray alloc] init];
weight =[[NSMutableArray alloc] init];
success =[[NSMutableArray alloc] init];
group =[[NSMutableArray alloc] init];
// Bind them to the data
//______________________________________________________________________________________
NSString *query = [NSString stringWithFormat:@"SELECT * FROM Tasks ORDER BY nextComplete "];
sqlite3_stmt *statement;
if (sqlite3_prepare_v2( database, [query UTF8String],
-1, &statement, nil) == SQLITE_OK) {
while (sqlite3_step(statement) == SQLITE_ROW) {
[ids addObject:[NSString stringWithFormat:@"%i",(int*) sqlite3_column_int(statement, 0)]];
[group addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 1)]];
[tasks addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 2)]];
[sched addObject:[NSString stringWithFormat:@"%i",(int*) sqlite3_column_int(statement, 3)]];
[lastComplete addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 4)]];
[nextComplete addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 5)]];
[success addObject:[NSString stringWithFormat:@"%s",(char*) sqlite3_column_text(statement, 6)]];
[weight addObject:[NSString stringWithFormat:@"%i",(int*) sqlite3_column_int(statement, 7)]];
}
sqlite3_finalize(statement);
}
在表格方法:cellForRowAtIndexPath中，我即时创建了控件，并将其文本属性设置为数组中的对象.下面是一个示例，我可以提供更多信息，但已经在这里写书了...:)
In the table method:cellForRowAtIndexPath, I create controls on the fly and set their text properties to objects in the array. Below is a sample, I can provide more but am already working on a book here... :)
/create the task label
NSString *tmpMessage;
tmpMessage = [NSString stringWithFormat:@"%@ every %@ days, for %@ points",[tasks objectAtIndex:indexPath.row],[sched objectAtIndex:indexPath.row],[weight objectAtIndex:indexPath.row]];
CGRect schedLabelRect = CGRectMake(0, 0, 250, 15);
UILabel *lblSched = [[UILabel alloc] initWithFrame:schedLabelRect];
lblSched.textAlignment = UITextAlignmentLeft;
lblSched.text = tmpMessage;
lblSched.font = [UIFont boldSystemFontOfSize:10];
[cell.contentView addSubview: lblSched];
[lblSched release];
我的numberOfSectionsInTableView方法看起来像这样
My numberOfSectionsInTableView method looks like this
// Figure out how many sections there are by a distinct count of the groups field
// The groups are entered by user when creating tasks
//______________________________________________________________________________________
NSString *groupquery = [NSString stringWithFormat:@"SELECT COUNT(DISTINCT groups) as Sum FROM Tasks"];
int sum;
sqlite3_stmt *statement;
if (sqlite3_prepare_v2( database, [groupquery UTF8String],
-1, &statement, nil) == SQLITE_OK) {
while (sqlite3_step(statement) == SQLITE_ROW) {
sum = sqlite3_column_int(statement, 0);
}
sqlite3_finalize(statement);
}
if (sum=0) {
return 1;
}
return 2;
}
我知道我在这里出错了，但这就是我的numberOfRowsInSection方法中的全部内容
I know I'm going wrong here but this is all that's in my numberOfRowsInSection method
return [ids count];
推荐答案
从数据模型的角度来看，这就是表格的外观:
This is what you want you table to look like from the perspective of the datamodel:
"Household" section
record 1 of (all records whose "group" column=="Household")
record 2 of (all records whose "group" column=="Household")
record 3 of (all records whose "group" column=="Household")
"Automotive" section
record 1 of (all records whose "group" column=="Automotive")
record 2 of (all records whose "group" column=="Automotive")
record 3 of (all records whose "group" column=="Automotive")
因此，您的数据模型必须反映此结构.现在，还没有.您只需将每一列加载到数组中，但数组之间没有任何关系，例如组"数组中的每个元素与任何其他数组中的任何元素都没有关系.这意味着您无法将每个组"与同一记录中的其他列相关联.
Therefore, your data model has to reflect this structure. Right now, it doesn't. You just load in each column into an array but you have no relationship between the arrays e.g. each element in the "group" array has no relationship to any element in any other array. This means you have no way to relate each "group" to the other columns in the same record.
由于SQL没有结构，因此您必须提供一个对象层，以将非结构化SQL返回转换为结构化SQL.
Since SQL has no structure, you have to provide an object layer to covert the unstructured SQL returns into a structured one.
(我的SQL生锈了，所以下面的所有SQL都是伪编码的.)
(My SQL is rusty so all the SQL below is pseudocoded.)
// for simplicity, assume that the SQL table is indexed and always returns the same order
@property (nonAtomic,retain) NSArray *group;
@sythesize group;
- (void) viewWillAppear:(BOOL)animated{
// here groups is the column with "Household", "Automotive" etc
// You want them unique because you want all "Household" under the same section
NSArray *unSortedgroup=SQL(every unique name in column "group");
self.group=[unsortedSectionName arraySortedUsing...]; //Sort the array however you wish
}//------------------------------------viewWillAppear:------------------------------------
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [self.group count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{
return [self.group objectAtIndex:section];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSString *sectionName=[self.group objectAtIndex:section];
NSUInteger *rowCount=SQL(count of all records whose "group" column == sectionName);
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
//... setup cell
NSString *sectionName=[self.group objectAtIndex:section];
NSArray *rowsForThisSection=SQL(indexs of all records whose "group" column == sectionName);
// the data for each row cell is now in/pointed to by [rowsForThisSection objectAtIndex:indexPath.row]
cell.idLabel.text=SQL(column "id" of record whose index is [rowsForThisSection objectAtIndex:indexPath.row])
// ... and so on for your other columns/attributes
}
这就是创建核心数据的原因.必须将SQL和其他串行形式插入面向对象的API使用的对象图中，这需要大量的胶合代码.使用Core Data，您可以创建一个对象图，然后让后端担心它如何存储到磁盘上.
This is why Core Data was created. SQL and other serial forms have to be shoehorned into the object graphs used by object oriented APIs and that takes a lot of glue code. With Core Data, you create an object graph and then let the back end worry about how it gets stored to disk.
有了Core Data，您可以用大约8行代码加上图形数据模型来完成所有这些工作.
With Core Data, you could do all this with about 8 lines of code plus the graphical data model.
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