[英]UITableView scrolling and redraw issue
我知道,如果我在自定义单元格中添加了一些图像和子视图,则必须重用该单元格,以便自定义控件不会出现在其他单元格上,但是这里还有其他问题。 我只想在第一部分的第一个单元格上有ImageView,所以在以下代码中使用了IndexPath.Section == 0和IndexPath.Row == 0条件,但是问题是当我滚动表时,另一个单元格会满足此条件,我的代码也会在该单元格上创建imageview。 我已经尝试过标记它并使用相同的标记的cellView,但它也无济于事。 单元问题是禁用少数单元的用户交互。 最终,在滚动之后,它将禁用所有单元的用户交互。 反正有解决办法吗?
谢谢。
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier] autorelease];
}
if(indexPath.section == 0 && indexPath.row == 0) {
UIImageView *imageView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"me.jpg"]] autorelease];
UIView *cellView = [[[UIView alloc] initWithFrame:CGRectMake(0, 0,320,132)] autorelease];
[imageView setFrame: CGRectMake(10, 10, 54, 54)];
[cellView addSubview:imageView];
cell.backgroundView = cellView;
return cell;
} else if(indexPath.row == 0) {
NSString * title = [NSString string];
switch (indexPath.section) {
case 1:
title = @"Friends";
break;
case 2:
title = @"Accounts";
break;
case 3:
title = @"Stats";
break;
default:
title = nil;
break;
}
cell.textLabel.text = title;
cell.userInteractionEnabled = NO;
return cell;
}
cell.textLabel.text = @"Test";
return cell;
}
[已解决]正确的代码:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier] autorelease];
if(indexPath.section == 0 && indexPath.row == 0) {
UIImageView *imageView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"me.jpg"]] autorelease];
cell.imageView.image = imageView.image;
cell.textLabel.text = nil;
cell.textLabel.textColor = [UIColor clearColor];
cell.textLabel.backgroundColor = [UIColor clearColor];
cell.userInteractionEnabled = YES;
return cell;
} else if(indexPath.row == 0) {
NSString * title = [NSString string];
switch (indexPath.section) {
case 1:
title = @"Friends";
break;
case 2:
title = @"Accounts";
break;
case 3:
title = @"Stats";
break;
default:
title = nil;
break;
}
cell.imageView.image = nil;
cell.textLabel.text = title;
cell.textLabel.textColor = [UIColor redColor];
cell.textLabel.backgroundColor = [UIColor clearColor];
cell.userInteractionEnabled = NO;
return cell;
}
cell.imageView.image = nil;
cell.textLabel.text = [cellItems objectAtIndex:(rows+indexPath.row-1)];
cell.textLabel.textColor = [UIColor blueColor];
cell.textLabel.backgroundColor = [UIColor clearColor];
cell.userInteractionEnabled = YES;
return cell;
}
[已验证的代码]
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *NormalCellIdentifier = @"NormalCell";
static NSString *TitleCellIdentifier = @"TitleCell";
NSString *neededCellType;
if(indexPath.section == 0 && indexPath.row == 0) {
neededCellType = TitleCellIdentifier;
} else {
neededCellType = NormalCellIdentifier;
}
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:neededCellType];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:neededCellType] autorelease];
//Only add content to cell if it is new
if([neededCellType isEqualToString: TitleCellIdentifier]) {
UIImageView *imageView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"me.jpg"]] autorelease];
cell.imageView.image = imageView.image;
}
}
if([neededCellType isEqualToString: NormalCellIdentifier]) {
NSString * title;
if(indexPath.row == 0) {
switch (indexPath.section) {
case 1:
title = @"Friends";
break;
case 2:
title = @"Accounts";
break;
case 3:
title = @"Stats";
break;
default:
title = nil;
break;
}
cell.textLabel.text = title;
cell.textLabel.textColor = [UIColor redColor];
cell.userInteractionEnabled = NO;
} else {
cell.userInteractionEnabled = YES;
cell.textLabel.textColor = [UIColor blueColor];
cell.textLabel.text = @"Test";
}
}
return cell;
}
我认为您的问题是单元的重用使得它不能被作为新单元创建的单元具有一些必须重新定义的属性。 例如,尝试将cell.userInteractionEnabled = YES分配给所有其他情况,然后查看结果。
问题在于,您不允许以后正确重用了正确显示图像的单元格,并且图像视图仍在其中。
这是两个解决方案:
在创建图像视图时设置它的标记值,然后在设置单元格时包括代码以检查并删除旧的imageView(如有必要)。
为需要图像视图的单元格和不需要图像视图的单元格分配不同的重用标识符。 然后,请确保仅在创建单元时才向它们添加新的图像视图,而不是在重用它们时向它们添加新的图像视图。
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {static NSString *NormalCellIdentifier = @"NormalCell"; static NSString *TitleCellIdentifier = @"TitleCell"; NSString *neededCellType;
if(indexPath.section == 0 && indexPath.row == 0) { neededCellType = TitleCellIdentifier; } else { neededCellType = NormalCellIdentifier; }
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:neededCellType];
if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:neededCellType] autorelease];
//Only add content to cell if it is new if([neededCellType isEqualToString: TitleCellIdentifier]) { UIImageView *imageView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"me.jpg"]] autorelease]; UIView *cellView = [[[UIView alloc] initWithFrame:CGRectMake(0, 0,320,132)] autorelease]; [imageView setFrame: CGRectMake(10, 10, 54, 54)]; [cellView addSubview:imageView]; cell.backgroundView = cellView; } }
if([neededCellType isEqualToString: NormalCellIdentifier]) { NSString * title; if(indexPath.row == 0) {
switch (indexPath.section) { case 1: title = @"Friends"; break; case 2: title = @"Accounts"; break; case 3: title = @"Stats"; break; default: title = nil; break; } cell.textLabel.text = title; cell.userInteractionEnabled = NO;
}
else { cell.textLabel.text = @"Test"; return cell; } } }
(最后几行从代码框中掉了出来)。 那应该做。
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