expanding collapsing uitableview sections

UITableView: Display and hide cells as a dropdown list

对UITableViewController进行更新(增加或删除)过程中可能遇到的问题

.h

 

interface list : UIViewController
{
    UITableView *mainTableView;
    
    NSString *dataForSection0;
    NSString *dataForSection2;
    NSMutableArray *demoData;
    NSMutableArray *demoData1;
    NSMutableArray *demoData2;
    int selectedValueIndex;
    int showingListSectionID;
    bool isShowingList;
}

.m

 



-- (void)viewDidLoad
{
    [super viewDidLoad];
 // Do any additional setup after loading the view.
    dataForSection0 = @""; //@"This is some cell content.";
    dataForSection2 = @""; //@"This is another cell content.";
    
    demoData = [[NSMutableArray alloc] init];

    demoData1 = [[NSMutableArray alloc] init];

    [demoData1 addObject:@"student name"];
    [demoData1 addObject:@"student1"];

    

    demoData2 = [[NSMutableArray alloc] init];
  
    [demoData2 addObject:@"class name"];
    [demoData2 addObject:@"class11"];
    [demoData2 addObject:@"class12"];
    [demoData2 addObject:@"class13"];
    
    isShowingList = NO;
    showingListSectionID = -1;

    selectedValueIndex = 0;
    
    //init
    [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"section0" ];
    [[NSUserDefaults standardUserDefaults] synchronize];
    [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"section1" ];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


//pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 2;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    
    // Return the number of rows in the section.

    
    // The number of the rows is depending on the section index.
    // The sections with indexes 0 and 2 will have only one row.

    
    ///假設你的 numberOfSectionsInTableView 判斷是 return dataSource && [dataSource count] ? 1 : 0 ; 的話，那一開始因為沒資料而 sections 個數為 0，所以更新指定 section 時會出錯，解法有兩個，一個是一開始 numberOfSectionsInTableView 就會回傳固定數值(非0)，這樣就不會出錯；另一個則是第一次新增資料時，呼叫 [self.tableView reloadData] 處理，之後才用 insertRowsAtIndexPaths 處理
    
    int rowCount = 1 ; //very important!
 
    switch (section) {
        case 0:
            
            if([[NSUserDefaults standardUserDefaults] boolForKey:@"section0"]==YES)
                rowCount = [demoData1 count]; 
            else
                rowCount = 1; 

            break;
        case 1:
            
            if([[NSUserDefaults standardUserDefaults] boolForKey:@"section1"]==YES)
                rowCount = [demoData2 count]; 
            else
                rowCount = 1; 
   
            break;
        default:
            break;
    }
    

    
    return rowCount;

}

// Add header titles in sections.
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section{
    if (section == 0) {
        return @""; //@"My first section";
    }
    else if (section == 1){
        return @""; //@"My demo section";
    }
    else{
        return @""; //@"Another section";
    }
}
// Set the row height.
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    return 60.0;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"CellIdentifier";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
    
    // Configure the cell...
   
    cell.selectionStyle = UITableViewCellSelectionStyleBlue;
    cell.accessoryType = UITableViewCellAccessoryNone;
    

    [[cell textLabel] setFont:[UIFont fontWithName:@"Marker Felt" size:16.0]];
    

    
    
     if ([indexPath section] == 0) {
         demoData = demoData1;
     }
     else if ([indexPath section] == 1){
         demoData = demoData2;
     }
    
    NSString *showSectionID = [[NSString alloc]initWithFormat:@"section%d",indexPath. section];
    

      // We'll set the dataForSection0 string value to the cell of that section.
        if ([[NSUserDefaults standardUserDefaults] boolForKey:showSectionID]==NO) { //hide list

            //[[cell textLabel] setText:[demoData objectAtIndex:selectedValueIndex]];
            
            //only show top one
            [[cell textLabel] setText:[demoData objectAtIndex:0]];
            
            cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
        }
        else{ //show list
            // Listing the array items.
            [[cell textLabel] setText:[demoData objectAtIndex:[indexPath row]]];
         
            if ([indexPath row] == selectedValueIndex) {
                cell.accessoryType = UITableViewCellAccessoryCheckmark; //check
            }
            else{
                cell.accessoryType = UITableViewCellAccessoryNone;
            }
        }

    
    return cell;
}

#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    
    showingListSectionID = indexPath.section;
    selectedValueIndex = [indexPath row];

    NSString *showSectionID = [[NSString alloc]initWithFormat:@"section%d",showingListSectionID];
    
     
    if([[NSUserDefaults standardUserDefaults] boolForKey:showSectionID]==YES)
    {
        [[NSUserDefaults standardUserDefaults] setBool:NO forKey:showSectionID ];
        [[NSUserDefaults standardUserDefaults] synchronize];
    }
    else{
        [[NSUserDefaults standardUserDefaults] setBool:YES forKey:showSectionID ];
        [[NSUserDefaults standardUserDefaults] synchronize];
        isShowingList = !isShowingList;
    }
   
        [mainTableView reloadSections:[NSIndexSet indexSetWithIndex:showingListSectionID] withRowAnimation:UITableViewRowAnimationFade];
  
}