我在iPhone应用程序中有UITableView我正在刷新（通过在动作方法中调用[self.tableView reloadData]动态嵌入其中一个UITableView单元格中的UISegmentedControl。刷新以更新其中一个单元格的文本值。
但是，以下代码似乎会产生不必要的副作用。似乎每次UITableView刷新时，它都会在现有的UITegmentedControl上创建一个新的UISegmentedControl实例（可能还有图像 - 我不确定）。
我注意到这一点的唯一原因是，每次刷新时，UISegmentedControl周围都会形成一个几乎无法察觉的边框，应用程序会明显减慢。我非常感谢任何有关我目前困境的建议/代码解决方案。
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
NSUInteger section = indexPath.section;
NSUInteger row = indexPath.row;
// Set up the cell...
//populates the personal info section
if (section == kPersonalInfoAddSection) {
if (row == kNameRow) {
//Other code irrelevant to this question was removed for the sake of clarity
}
else if(row == kHeightRow) {
cell.imageView.image = [UIImage imageNamed:@"tableview_height_label.png"];
//THIS IS THE TEXT I'M TRYING TO UPDATE
cell.textLabel.text = [Formatter formatHeightValue:mainUser.heightInMM forZone:self.heightZone];
cell.detailTextLabel.text = REQUIRED_STRING;
}
}
//populates the units section
if (section == kUnitsSection) {
if (row == kHeightUnitsRow) {
NSArray *heightUnitsSegments = [[NSArray alloc] initWithObjects:FT_AND_IN_STRING, M_AND_CM_STRING, nil];
UISegmentedControl *heightUnitControl = [[UISegmentedControl alloc] initWithItems:heightUnitsSegments];
CGRect segmentRect = CGRectMake(90, 7, 200, 30);
[heightUnitControl setFrame:segmentRect];
//[heightUnitControl setSelectedSegmentIndex:0];
[heightUnitControl addTarget:self action:@selector(heightSegmentClicked:) forControlEvents:UIControlEventValueChanged];
heightUnitControl.tag = kHeightSegmentedControlTag;
cell.textLabel.text = @"Height:";
cell.detailTextLabel.text = @"(units)";
[cell.contentView addSubview:heightUnitControl];
[heightUnitsSegments release];
[heightUnitControl release];
}
else if(row == kWeightUnitsRow) {
//Other code irrelevant to this question was removed for the sake of clarity
}
}
return cell;
}
提前谢谢大家！
答案 0 :(得分：2)
你是对的，它正在创建一个UISegmentedControl的新实例。这是因为您使用的是通用单元格标识符@“Cell”，然后每次都添加UISegmentedControl，从不删除它。包含UISegmentedControl的单元格被缓存，您将检索缓存的单元格并再次添加控件。
您可以使用更具体的单元格标识符，如果单元格！= nil，您知道它已包含UISegmentedControl。或者每次使用已经包含控件的缓存单元格时创建一个新单元格。
使用图像视图，您只需设置单元格图像视图属性，而无需向单元格添加新视图，以便一个可以，每次都会替换它。
由于您尝试更新的文本与UISegmentedControl没有关系，我认为您应该能够使用更具体的单元格标识符，并仅在单元格创建时添加控件。
答案 1 :(得分：0)
- (void)viewDidLoad {
[super viewDidLoad];
NSArray *arr1=[NSArray arrayWithObjects:@"img1.jpg",@"img2.jpg",nil];
NSArray *arr2=[NSArray arrayWithObjects:@"img1.jpg",@"img2.jpg",@"img3.jpg",@"img4.jpg",@"img5.jpg",@"img6.jpg",nil];
NSArray *arr3=[NSArray arrayWithObjects:@"img6.jpg",@"img5.jpg",@"img2.jpg",@"img1.jpg",nil];
Imgs = [[NSArray alloc] initWithArray:[NSArray arrayWithObjects:arr1,arr2,arr3,nil]];
NSDictionary *dic1=[NSDictionary dictionaryWithObjectsAndKeys:@"Ahmedabad",@"Name",@"Picture 5.png",@"Rating",@"Picture 1.png",@"Photo",arr1,@"img",nil];
NSDictionary *dic2=[NSDictionary dictionaryWithObjectsAndKeys:@"Rajkot",@"Name",@"Picture 5.png",@"Rating",@"Picture 2.png",@"Photo",nil];
NSDictionary *dic3=[NSDictionary dictionaryWithObjectsAndKeys:@"Baroda",@"Name",@"Picture 5.png",@"Rating",@"Picture 7.png",@"Photo",nil];
tblArray=[[NSArray alloc] initWithObjects:dic1,dic2,dic3,nil];
[myTbl reloadData];
}
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
self.navigationController.navigationBarHidden=NO;
[self.navigationController.navigationBar setUserInteractionEnabled:YES];
}
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
self.navigationController.navigationBarHidden=YES;
}
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
return 1;
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return [tblArray count];
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
NSString *CellIdentifer=[NSString stringWithFormat:@"%i",indexPath.row];
UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:CellIdentifer];
if(cell==nil){
cell=[self myCustomCell:CellIdentifer dicToSet:[tblArray objectAtIndex:indexPath.row]];
[cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
}
return cell;
}
-(UITableViewCell*)myCustomCell:(NSString*)CellIdentifer dicToSet:(NSDictionary*)dicToSet{
UITableViewCell *cell=[[[UITableViewCell alloc] initWithFrame:CGRectMake(0, 0, 320, 44) reuseIdentifier:CellIdentifer] autorelease];
UIImageView *imgV=[[UIImageView alloc] initWithFrame:CGRectMake(2, 2, 40, 40)];
[imgV setImage:[UIImage imageNamed:[dicToSet valueForKey:@"Photo"]]];
[cell addSubview:imgV];
[imgV release];
UILabel *lbl=[[UILabel alloc] initWithFrame:CGRectMake(44, 2, 276, 20)];
[lbl setText:[dicToSet valueForKey:@"Name"]];
[cell addSubview:lbl];
[lbl setBackgroundColor:[UIColor clearColor]];
[lbl setFont:[UIFont fontWithName:@"Helvetica-Bold" size:18]];
[lbl release];
UIImageView *imgV1=[[UIImageView alloc] initWithFrame:CGRectMake(44, 24, 70, 20)];
[imgV1 setImage:[UIImage imageNamed:[dicToSet valueForKey:@"Rating"]]];
[cell addSubview:imgV1];
[imgV1 release];
return cell;
}
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
nxtPlcDtl=[[plcFullDtl alloc] initWithNibName:@"plcFullDtl" bundle:nil];
nxtPlcDtl.dict=[[NSDictionary alloc] initWithDictionary:[tblArray objectAtIndex:indexPath.row]];
nxtPlcDtl.Imgs = [Imgs objectAtIndex:indexPath.row];
nxtPlcDtl.comment1 = [comment1 objectAtIndex:indexPath.row];
nxtPlcDtl.vedio = [vedio objectAtIndex:indexPath.row];
[self.navigationController pushViewController:nxtPlcDtl animated:YES];
}