从表格视图单元格中获取分段控制值

Question

如何从 tableviewcells 中的分段控件中获取值（选定状态）？ 当我按下“获取状态”按钮时，它应该返回每个分段控件的值。我尝试了不同的方法，但我找不到一种有效的方法:(

到目前为止我的代码：

- (void)viewDidLoad
{
[super viewDidLoad];

tableData = [[NSMutableArray alloc] initWithCapacity:0];
tableData = [NSArray arrayWithObjects:@"First", @"Second", @"Third", nil];
}

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [tableData count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = nil;
cell = [tableView dequeueReusableCellWithIdentifier:@"StateCell"];
if (cell == nil)
{
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"StateCell"];
}

//Config cell..
cell.textLabel.text = [tableData objectAtIndex:indexPath.row];

NSArray *itemArray = [NSArray arrayWithObjects: @"1", @"2", @"3", nil];
UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:itemArray];
segmentedControl.frame = CGRectMake(110, 7, 100, 28);

[cell.contentView addSubview:segmentedControl];

return cell;
[[self tableView] reloadData];
}

- (IBAction)getStates:(id)sender {

// Ruturn the current selected statement, for the individual cell's segmentedcontrol..
// Ex. First = SelectedState 1, Second = SelectedState 0 & Third = SelectedState 2..

}

所以我真正想要的是；是“获取状态”按钮操作必须执行的操作..

感谢您的宝贵时间！

Answer 1

您的代码有几个问题。大多数情况发生是因为 UITableView 重用了它的单元格。

每次显示单元格时，您都会创建一个新的 UISegmentedControl，但您不应该这样做。仅当您创建单元格时才应创建 UISegmentedControl，将该代码移动到 cell == nil)。

您没有保存段状态的数据源。您不应该在视图中保存状态，尤其是在处理 tableView 时，因为单元格被重用。

这里有一个示例，它将获得您需要的功能。

// this is an object of your model, it has a title and saves the selected index
@interface MBFancyObject : NSObject
@property (strong, nonatomic) NSString *title;
@property (assign, nonatomic) NSInteger selectedIndex;
@end

@implementation MBFancyObject
@end


@interface MasterViewController () {
    NSMutableArray *_objects;     // stores instances of MBFancyObject
}
@end

@implementation MasterViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // set up the model
    _objects = [NSMutableArray array];
    for (NSInteger i = 0; i < 6; i++) {
        MBFancyObject *object = [[MBFancyObject alloc] init];
        object.title = [NSString stringWithFormat:@"Object #%ld", (long)i];
        object.selectedIndex = i % 3;
        [_objects addObject:object];
    }

    UIBarButtonItem *button = [[UIBarButtonItem alloc] initWithTitle:@"Get States" style:UIBarButtonItemStyleBordered target:self action:@selector(logStates:)];
    self.navigationItem.rightBarButtonItem = button;
}

#pragma mark - Table View

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return _objects.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"FancyCell"];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"FancyCell"];
        // add the segmentedControl when you create a new cell
        UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:@[@"1", @"2", @"3"]];
        segmentedControl.frame = CGRectMake(110, 7, 100, 28);
        [cell.contentView addSubview:segmentedControl];

        // add an action so we can change our model if the view changes
        [segmentedControl addTarget:self action:@selector(didChangeSegmentedControl:) forControlEvents:UIControlEventValueChanged];

        // use a tag so we can retrieve the segmentedControl later
        segmentedControl.tag = 42;
    }
    // either if the cell could be dequeued or you created a new cell,
    // segmentedControl will contain a valid instance 
    UISegmentedControl *segmentedControl = (UISegmentedControl *)[cell.contentView viewWithTag:42];

    MBFancyObject *object = _objects[indexPath.row];
    cell.textLabel.text = object.title;
    segmentedControl.selectedSegmentIndex = object.selectedIndex;
    return cell;
}

- (IBAction)didChangeSegmentedControl:(UISegmentedControl *)sender {
    // transform the origin of the cell to the frame of the tableView
    CGPoint senderOriginInTableView = [self.tableView convertPoint:CGPointZero fromView:sender];

    NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:senderOriginInTableView];
    NSAssert(indexPath, @"must have a valid indexPath");
    MBFancyObject *object = _objects[indexPath.row];
    object.selectedIndex = sender.selectedSegmentIndex;
}

- (IBAction)logStates:(id)sender {
    // query the model, not the view
    for (NSInteger i = 0; i < [_objects count]; i++) {
        MBFancyObject *object = _objects[i];
        NSLog(@"Object \"%@\" - %ld", object.title, (long)object.selectedIndex);

        // since you have only one section, each indexPath is 0,i
        NSIndexPath *indexPath = [NSIndexPath indexPathForRow:i inSection:0];
    }
}

@end

Answer 2

使用一个数组来存储所有的段控件值，当点击一个段控件时，只需相应地改变值即可。

Answer 3

你在这里重用有严重的问题

永远不要在 tableView:cellForRowAtIndexPath: 方法中分配新的 UI 元素，除非它在 ​​if 条件 if (cell == nil) 中

将tableView:cellForRowAtIndexPath: 中的内容更改为

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"StateCell"];
if (cell == nil)
{
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"StateCell"];

    // Add the Segmented Control
    NSArray *itemArray = [NSArray arrayWithObjects: @"1", @"2", @"3", nil];
    UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:itemArray];
    segmentedControl.frame = CGRectMake(110, 7, 100, 28);
    segmentedControl.tag = 1;
    [cell addSubview:segmentedControl];
}

//Config cell..
cell.textLabel.text = [tableData objectAtIndex:indexPath.row];

// Get that Segmented Control
UISegmentedControl *segmentedControl = (UISegmentedControl *)[cell viewWithTag:1];
segmentedControl.selectedSegmentIndex = 0; // Set your default value here or add your data in an array and read from that array

return cell;

然后在按钮的动作中这样做

for (UITableViewCell *cell in [tableView visibleCells]) {
    UISegmentedControl *segmentedControl = (UISegmentedControl *)[cell viewWithTag:1];
    NSLog(@"%d",segmentedControl.selectedSegmentIndex);
}

但是，除非您的表格中只有 3 个单元格以避免重用或可见性问题，否则此代码并不完美