我正在尝试创建展开/折叠单元格。在每个单元格上，它具有边界底部的UIView子视图。如果展开，边框也应该到达单元格的底部。它在单元的初始加载时工作正常，但是，当我向下滚动时，边框不再向下移动。
我正在通过taskOptionsExpand方法调整边框originY。该方法是通过[cell.contentView viewWithTag:2]获取边框视图。
以下代码：
#import "HomeViewController.h"
@interface HomeViewController ()<UITableViewDelegate, UITableViewDataSource>
@property (strong, nonatomic) UITableView *tableView;
@property (strong, nonatomic) NSIndexPath *selectedIndexPath;
@end
@implementation HomeViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.selectedIndexPath = nil;
[self.view addSubview:self.tableView];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (UITableView *)tableView
{
if (!_tableView) {
_tableView = [[UITableView alloc] init];
_tableView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
_tableView.delegate = self;
_tableView.dataSource = self;
_tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
[_tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"Cell"];
[_tableView addSubview:self.tableRefreshControl];
}
return _tableView;
}
# pragma mark - table view delegates
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 100;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([self.selectedIndexPath isEqual:indexPath]) {
return 80;
}else{
return 50;
}
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
// text view
UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(20, 0, self.view.frame.size.width-20, 50)];
view1.backgroundColor = [UIColor clearColor];
view1.tag = 0;
UILabel *title = [[UILabel alloc] initWithFrame:view1.frame];
title.text = @"Lorem ipsum";
title.textColor = [UIColor grayColor];
[view1 addSubview:title];
// options view
UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(0, 50, self.view.frame.size.width, 30)];
view2.backgroundColor = [UIColor orangeColor];
view2.tag = 1;
// border bottom
CGRect frame = CGRectMake(20, 49, self.view.frame.size.width-40, 1);
if ([self.selectedIndexPath isEqual:indexPath]) {
frame.origin.y = 79; //expand
} else {
}
UIView *border = [[UIView alloc] initWithFrame:frame];
border.backgroundColor = [UIColor blueColor];
border.tag = 2;
cell.clipsToBounds = YES;
[cell.contentView addSubview:view1];
[cell.contentView addSubview:view2];
[cell.contentView addSubview:border];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([self.selectedIndexPath isEqual:indexPath]) {
[self taskOptionsExpand:NO indexPath:indexPath];
self.selectedIndexPath = nil;
} else {
[self taskOptionsExpand:YES indexPath:indexPath];
[self taskOptionsExpand:NO indexPath:self.selectedIndexPath];
self.selectedIndexPath = indexPath;
}
[tableView beginUpdates];
[tableView endUpdates];
}
- (void) taskOptionsExpand:(BOOL) expand indexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
UIView *border = [cell.contentView viewWithTag:2];
NSLog(@"border: %@", border);
if (expand) {
border.frame = CGRectMake(20, 79, self.view.frame.size.width-40, 1);
}else{
border.frame = CGRectMake(20, 49, self.view.frame.size.width-40, 1);
}
}
@end
答案 0 :(得分：1)
滚动table view时，单元格为dequeued以获取reusable cell，而reusable cell已有viewWithTag 2 （因为已添加）当创建重用的单元格时，因此添加another view with tag 2将产生上述问题。要解决上述问题，您应删除之前添加的viewWithTag 2，然后重新添加具有相同标记的视图，例如 -
// remove (previously added) border if it exists
UIView *border = nil;
border = [cell.contentView viewWithTag:2];
if(border)
[border removeFromSuperview];
// again create border view
将您的cellForRowAtIndexPath：方法更新为
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
// text view
UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(20, 0, self.view.frame.size.width-20, 50)];
view1.backgroundColor = [UIColor clearColor];
view1.tag = 0;
UILabel *title = [[UILabel alloc] initWithFrame:view1.frame];
title.text = @"Lorem ipsum";
title.textColor = [UIColor grayColor];
[view1 addSubview:title];
// options view
UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(0, 50, self.view.frame.size.width, 30)];
view2.backgroundColor = [UIColor orangeColor];
view2.tag = 1;
// border bottom
CGRect frame = CGRectMake(20, 49, self.view.frame.size.width-40, 1);
if ([self.selectedIndexPath isEqual:indexPath]) {
frame.origin.y = 79; //expand
} else {
}
UIView *border = nil;
border = [cell.contentView viewWithTag:2];
if(border)
[border removeFromSuperview];
border = [[UIView alloc] initWithFrame:frame];
border.backgroundColor = [UIColor blueColor];
border.tag = 2;
cell.clipsToBounds = YES;
[cell.contentView addSubview:view1];
[cell.contentView addSubview:view2];
[cell.contentView addSubview:border];
// release your allocated instances after adding them
[view1 release];
[view2 release];
[border release];
return cell;
}
此外，您应该release将subviews allocated view1, view2, border添加到单元格的内容视图后[view1 release];
[view2 release];
[border release];
~/Products/details.aspx?product=26-Toshiba Qosmio Notebook
这将使得从2到1保留计数，并且当细胞被释放时，它们将从那些细胞中移除。
答案 1 :(得分：0)
表视图重用单元格。当单元格在屏幕外滚动时，它将被添加到队列中，并将重新用于下一个要在屏幕上滚动的单元格。这意味着tableView:cellForRowAtIndexPath:方法中的配置代码将在不同的indexPaths上在同一单元格上多次运行。由于您只是在每次配置代码运行时添加border视图，因此它们将堆叠在另一个之上。当您致电viewWithTag:时，您只会获得您添加的多个观看次数之一。
正确的方法是创建一个自定义单元格（UITableViewCell的子类），其中包含需要配置的每个子视图的属性（如果使用xibs / storyboard，则为IBOutlet），以便它们可以是访问。