ios - iOS：UITableViewController -- cellForRowAtIndexPath 单元格创建

Question

我知道 Apple 文档没有指定 cellForRowAtIndexPath 按顺序排列，即首先它会转到第 0 节，索引 0；然后是第 0 节，索引 2；然后是第 1 节，索引 0....等等。我认为它会跳来跳去。

下面有什么更好的方法来完成？目前我不断收到错误

NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 3 beyond bounds [0 .. 2]'

错误出现 b/c 我认为 cellForRowAtIndexPath 会跳来跳去并标记 *sectioned = NULL，因此会跳过该条件，它会转到一个空数组或通过出现错误条件而超出索引计数。

这是代码：

... declared and synthesized 
NSManaged *object;
@property (strong, nonatomic) NSNumber *sevenDaysSectionFilled;
@property (strong, nonatomic) NSNumber *fourteenDaysSectionFilled;
@property (strong, nonatomic) NSNumber *thirtyDaysSectionFilled;


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    object = NULL;
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    if (indexPath.section == 0)
    {
        if ((SevenDaysArraySectioned == [NSNumber numberWithBool:YES]) && (sevenDaysSectionFilled != [NSNumber numberWithBool:YES]))
        {
            object = [pastSevenDayArray objectAtIndex:indexPath.row];
            sevenDaysSectionFilled = [NSNumber numberWithBool:YES];
        }

        else if ((fourteenDaysArraySectioned == [NSNumber numberWithBool:YES]) && (fourteenDaysSectionFilled != [NSNumber numberWithBool:YES]))
        {
            object = [pastFourteenDaysArray objectAtIndex:indexPath.row];
            fourteenDaysSectionFilled = [NSNumber numberWithBool:YES];
        }

        else if ((thirtyDaysArraySectioned == [NSNumber numberWithBool:YES]) && (thirtyDaysSectionFilled != [NSNumber numberWithBool:YES]))
        {
            object = [pastThirtyDaysArray objectAtIndex:indexPath.row];
            thirtyDaysSectionFilled = [NSNumber numberWithBool:YES];
        }

    else if (indexPath.section == 1)
    {
        if ((fourteenDaysArraySectioned == [NSNumber numberWithBool:YES]) && (fourteenDaysSectionFilled != [NSNumber numberWithBool:YES]))
        {
            object = [pastFourteenDaysArray objectAtIndex:indexPath.row];
            fourteenDaysSectionFilled = [NSNumber numberWithBool:YES];
        }

        else if ((thirtyDaysArraySectioned == [NSNumber numberWithBool:YES]) && (thirtyDaysSectionFilled != [NSNumber numberWithBool:YES]))
        {
            object = [pastThirtyDaysArray objectAtIndex:indexPath.row];
            thirtyDaysSectionFilled = [NSNumber numberWithBool:YES];
        }

    else if (indexPath.section == 2)
    {
        if ((thirtyDaysArraySectioned == [NSNumber numberWithBool:YES]) && (thirtyDaysSectionFilled != [NSNumber numberWithBool:YES]))
        {
             object = [pastThirtyDaysArray objectAtIndex:indexPath.row];
            thirtyDaysSectionFilled = [NSNumber numberWithBool:YES];
        }
     }

NSString *entityName = [[object entity]name];
cell.textLabel.text = [NSString stringWithFormat:@"%@   %i", entityName, [indexPath row]];

  object = NULL;
  return cell;
}

请让我知道是否有更好的方法来实现这一点。谢谢。

*编辑

这有点复杂，但这里是：

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    numberOfSections = 0;

    if ([pastSevenDayArray count] > 0) numberOfSections++;
    if ([pastFourteenDaysArray count] > 0) numberOfSections++;
    if ([pastThirtyDaysArray count] > 0) numberOfSections++;
    if ([pastSixtyDaysArray count] > 0) numberOfSections++;
    if ([pastNinteyDaysArray count] > 0) numberOfSections++;
    if ([pastArray count] > 0) numberOfSections++;

    [self numberOfCells];


    return numberOfSections;
}

细胞数

-(void)numberOfCells
{
    for (int section = 0; section<numberOfSections; section ++)
    {
        if (section == 0)
        {
            if ([pastSevenDayArray count] > 0)
            {
                SevenDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionZeroCellCount = [pastSevenDayArray count];
                sectionZeroHeader = sevenDaysSectionLabel;
            }
            else if ([pastFourteenDaysArray count] > 0)
            {
                fourteenDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionZeroCellCount = [pastFourteenDaysArray count];
                sectionZeroHeader = fourteenDaysSectionLabel;
            }
            else if ([pastThirtyDaysArray count] > 0)
            {
                thirtyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionZeroCellCount = [pastThirtyDaysArray count];
                sectionZeroHeader = thirtyDaysSectionLabel;
            }
            else if ([pastSixtyDaysArray count] > 0)
            {
                sixtyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionZeroCellCount = [pastSixtyDaysArray count];
                sectionZeroHeader = sixtyDaysSectionLabel;

            }
            else if ([pastNinteyDaysArray count] > 0)
            {
                ninetyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionZeroCellCount = [pastNinteyDaysArray count];
                sectionZeroHeader = ninetyDaysSectionLabel;
            }
            else if ([pastArray count] > 0)
            {
                pastArraySectioned = [NSNumber numberWithBool:YES];
                sectionZeroCellCount = [pastArray count];
                sectionZeroHeader = pastSectionLabel;
            }
        }

        else if (section == 1)
        {    
            if (([pastFourteenDaysArray count] > 0) && (fourteenDaysArraySectioned != [NSNumber numberWithBool:YES]))

            {
                fourteenDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionOneCellCount = [pastFourteenDaysArray count];
                sectionOneHeader = fourteenDaysSectionLabel;
            }
            else if (([pastThirtyDaysArray count] > 0) && (thirtyDaysArraySectioned != [NSNumber numberWithBool:YES]))

            {
                thirtyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionOneCellCount = [pastThirtyDaysArray count];
                sectionOneHeader = thirtyDaysSectionLabel;
            }
            else if (([pastSixtyDaysArray count] > 0) && (sixtyDaysArraySectioned != [NSNumber numberWithBool:YES]))
            {
                sixtyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionOneCellCount = [pastSixtyDaysArray count];
                sectionOneHeader = sixtyDaysSectionLabel;
            }
            else if (([pastNinteyDaysArray count] > 0) && (ninetyDaysArraySectioned != [NSNumber numberWithBool:YES]))

            {
                ninetyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionOneCellCount = [pastNinteyDaysArray count];
                sectionOneHeader = ninetyDaysSectionLabel;
            }
            else if (([pastArray count] > 0) && (pastArraySectioned != [NSNumber numberWithBool:YES]))
            {
                pastArraySectioned = [NSNumber numberWithBool:YES];
                sectionOneCellCount = [pastArray count];
                sectionOneHeader = pastSectionLabel;
            }
        }
        else if (section ==2)
        {
            if (([pastThirtyDaysArray count] > 0) && (thirtyDaysArraySectioned != [NSNumber numberWithBool:YES]))

            {
                thirtyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionTwoCellCount = [pastThirtyDaysArray count];
                sectionTwoHeader = thirtyDaysSectionLabel;
            }
            else if (([pastSixtyDaysArray count] > 0) && (sixtyDaysArraySectioned != [NSNumber numberWithBool:YES]))
            {
                sixtyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionTwoCellCount = [pastSixtyDaysArray count];
                sectionTwoHeader = sixtyDaysSectionLabel;
            }
            else if (([pastNinteyDaysArray count] > 0) && (ninetyDaysArraySectioned != [NSNumber numberWithBool:YES]))

            {
                ninetyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionTwoCellCount = [pastNinteyDaysArray count];
                sectionTwoHeader = ninetyDaysSectionLabel;
            }
            else if (([pastArray count] > 0) && (pastArraySectioned != [NSNumber numberWithBool:YES]))
            {
                pastArraySectioned = [NSNumber numberWithBool:YES];
                sectionTwoCellCount = [pastArray count];
                sectionTwoHeader = pastSectionLabel;
            }
        }
        else if (section ==3)

        {
            NSLog(@"Entered Section %i", section);

            if (([pastSixtyDaysArray count] > 0) && (sixtyDaysArraySectioned != [NSNumber numberWithBool:YES]))            {
                sixtyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionThreeCellCount = [pastSixtyDaysArray count];
                sectionThreeHeader = sixtyDaysSectionLabel;
            }
            else if (([pastNinteyDaysArray count] > 0) && (ninetyDaysArraySectioned != [NSNumber numberWithBool:YES]))
            {
                ninetyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionThreeCellCount = [pastNinteyDaysArray count];
                sectionThreeHeader = ninetyDaysSectionLabel;          
            }
            else if (([pastArray count] > 0) && (pastArraySectioned != [NSNumber numberWithBool:YES]))
            {
                pastArraySectioned = [NSNumber numberWithBool:YES];
                sectionThreeCellCount = [pastArray count];
                sectionThreeHeader = pastSectionLabel;
            }
        }
        else if (section ==4)
        {
            NSLog(@"Entered Section %i", section);

            if (([pastNinteyDaysArray count] > 0) && (ninetyDaysArraySectioned != [NSNumber numberWithBool:YES]))
            {
                ninetyDaysArraySectioned = [NSNumber numberWithBool:YES];
                sectionFourCellCount = [pastNinteyDaysArray count];
                sectionFourHeader = ninetyDaysSectionLabel;
            }
            else if (([pastArray count] > 0) && (pastArraySectioned != [NSNumber numberWithBool:YES]))
            {
                pastArraySectioned = [NSNumber numberWithBool:YES];
                sectionFourCellCount = [pastArray count];
                sectionFourHeader = pastSectionLabel;
            }
        }

        else if (section ==5)
        {
            NSLog(@"Entered Section %i", section);

            if (([pastArray count] > 0) && (pastArraySectioned != [NSNumber numberWithBool:YES]))
            {
                pastArraySectioned = [NSNumber numberWithBool:YES];
                sectionFiveCellCount = [pastArray count];
                sectionFiveHeader = pastSectionLabel;
            }
        }

    }

}

numberOfRowsInSection

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

    if (section == 0)
    {
        return sectionZeroCellCount;
    }

    else if (section == 1)
    {
        return sectionOneCellCount;
    }
    else if (section == 2)
    {
        return sectionTwoCellCount;
    }
    else if (section == 3)
    {
        return sectionThreeCellCount;
    }
    else if (section == 4)
    {
        return sectionFourCellCount;
    }
    if (section == 5)
    {
        return sectionFiveCellCount;
    }
}

编辑 2

标题：

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    return 30.0;
}

- (UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 150)];
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 3, tableView.bounds.size.width - 10, 25)];
    label.backgroundColor = [UIColor clearColor];
    [label setFont:[UIFont boldSystemFontOfSize:16]];
    label.textColor = [UIColor whiteColor];

    if (section == 0)
    {
        label.text = sectionZeroHeader;
    }
    else if (section == 1)
    {
        label.text = sectionOneHeader;
    }

    else if (section == 2)
    {
        label.text = sectionTwoHeader;
    }
    else if (section == 3)
    {
        label.text = sectionThreeHeader;
    }
    else if (section == 4)
    {
        label.text = sectionFourHeader;
    }
    else if (section == 5)
    {
        label.text = sectionFiveHeader;
    }    

    [headerView addSubview:label];
    return headerView;
}

score 1 · Accepted Answer

我认为您必须确保设置适当

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section;

和

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView;

如果你想有多个部分并且在每个部分中有很多行，请使用 NSDictionary 并设置键 --> 数组值，然后

NSDictionary *dict = @{@"section1": @[@"obj1", @"obj2"],@"section2": @[@"obj3", @"obj4"]};
NSInteger numberOfSections = [[dict allKeys] count];// return in numberOfSections
NSArray *values = [dict valueForKey:@"obj1"];// get appropriate array

score 1 · Accepted Answer

在各种实例变量中维护了大量的状态，而这些状态并非必须如此。我们可以使用集合和其他数据结构来构建表应该如何的定义，然后在我们的数据源/委托方法中引用它。

这个视图控制器的基本思想是每个部分都由一个CVSectionModel对象表示，该对象包含该部分的行数据，以及特定于部分的信息，例如标题视图。在内部viewDidLoad我们构建这些部分模型，并且任何时候我们完成更新我们的数据，我们都应该重新构建它们。要尝试不同的数据工作安排，请将调用替换为viewDidLoad其他testCase1测试方法之一。

我们维护一系列部分模型，并且仅在有内容要显示的部分创建模型。如您所见，这简化了计算从哪个数组中获取行信息以及每个部分中有多少行的计算。我们只是简单地询问节模型一个节要做什么，而不是同步几个不同的实例变量。

请注意，此表控制器不支持更精细的内容插入、删除或重新排序动画，因此如果需要，则需要进行额外的工作。但是，它确实支持在更新后定期重新加载表，这可以在 viewDidLoad 后 10 秒运行的块中看到。

请检查代码并提出任何问题。这是实现文件，但头文件中除了@interface CVViewController: UIViewController @end.

@interface CVSectionModel : NSObject

@property (nonatomic) NSArray *rowModels;
@property (nonatomic) NSString *sectionTitle;
@property (nonatomic) NSInteger tag; // possibly useful for animations, different behavior on section, etc.

@end

@implementation CVSectionModel

@end


@interface CVViewController () <UITableViewDataSource, UITableViewDelegate>

@property (weak, nonatomic) IBOutlet UITableView *tableView;

@property (nonatomic) NSArray *sectionModels;

@property (nonatomic) NSArray *sevenDays;
@property (nonatomic) NSArray *fourteenDays;
@property (nonatomic) NSArray *thirtyDays;

@end

@implementation CVViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // In your application, you'll be loading and processing your real data
    // But here I'm just going to simulate a number of cases with strings for illustration
    // Call the other methods to try different configurations
    [self testCase1];

    // We call this once on viewDidLoad. You'll also want to call it whenever you update the underlying data, as in the block below
    [self processSectionData];

    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"IDENTIFIER"];

    // Demonstrate support for modifying the underlying data and refresh the view.
    // Uncomment to test it.
//    double delayInSeconds = 10.0;
//    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
//    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
//        [self testCase2];
//        [self processSectionData];
//        [self.tableView reloadData];
//    });
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return [self.sectionModels count];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [((CVSectionModel *)self.sectionModels[section]).rowModels count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"IDENTIFIER"];
    // In your app this appears to be an NSManagedObject of some type, here it's just a string
    NSString *modelForRow = ((CVSectionModel *)self.sectionModels[indexPath.section]).rowModels[indexPath.row];
    cell.textLabel.text = modelForRow;
    return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    return 30.0;
}

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    NSString *sectionTitle = ((CVSectionModel *)self.sectionModels[section]).sectionTitle;
    UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 150)];
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 3, tableView.bounds.size.width - 10, 25)];
    label.backgroundColor = [UIColor clearColor];
    [label setFont:[UIFont boldSystemFontOfSize:16]];
    label.textColor = [UIColor whiteColor];
    label.text = sectionTitle;
    [headerView addSubview:label];
    return headerView;
}

- (void)processSectionData
{
    NSArray *allDayArrays = @[self.sevenDays, self.fourteenDays, self.thirtyDays];
    // You won't use hard-coded strings here - use your sevenDaysSectionLabel, etc. variables instead
    NSArray *labelTitles = @[@"7 days", @"14 days", @"30 days"];
    NSMutableArray *mutableSectionModels = [NSMutableArray array];

    [allDayArrays enumerateObjectsUsingBlock:^(NSArray *array, NSUInteger index, BOOL *stop) {
        if ([array count] > 0) {
            CVSectionModel *sectionModel = [[CVSectionModel alloc] init];
            sectionModel.rowModels = array;
            sectionModel.sectionTitle = labelTitles[index];
            sectionModel.tag = index+1; // track this to enable re-ordering in the future
            [mutableSectionModels addObject:sectionModel];
        }
    }];

    // If Animating insertions / deletions will require something more elaborate
    self.sectionModels = [mutableSectionModels copy];
}

// Case 1:
// All three populated
- (void)testCase1
{
    self.sevenDays = @[@"sevendayitem1", @"sevendayitem2", @"sevendayitem3", @"sevendayitem4"];
    self.fourteenDays = @[@"14day item 1", @"14 day item 2"];
    self.thirtyDays = @[@"30 day item 1", @"30 day item 2", @"30 day item 3"];
}

// Case 2:
// self.fourteenDays is empty
- (void)testCase2
{
    self.sevenDays = @[@"sevendayitem1", @"sevendayitem2", @"sevendayitem3", @"sevendayitem4"];
    self.fourteenDays = @[];
    self.thirtyDays = @[@"30 day item 1", @"30 day item 2", @"30 day item 3"];
}

// Case 3:
// self.thirtydays is the only one
- (void)testCase3
{
    self.sevenDays = @[];
    self.fourteenDays = @[];
    self.thirtyDays = @[@"30 day item 1", @"30 day item 2", @"30 day item 3"];
}

@end

ios - iOS：UITableViewController -- cellForRowAtIndexPath 单元格创建

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